Universe Today

The gravitational wave background was first detected in 2016. It was announced following the release of the first data set from the European Pulsar Timing Array. A second set of data has just been released and, joined by the Indian Pulsar Timing Array, both studies confirm the existence of the background. The latest theory seems to suggest that we’re seeing the combined signal of supermassive black hole mergers. 

Gravitational waves are ripples in spacetime caused by violent processes in the Universe. They were predicted by Einstein back in 1916 as part of his General Theory of Relativity. It is thought the waves are generated by accelerating masses such as merging black holes, colliding neutron stars and the like. They are expected to be able to travel through space, largely unimpeded by anything in their way.  Their existence was first detected in September 2015 by the Laser Interferometer Gravitational-Wave Observatory, or LIGO. They are thought to have come from a gravitational merger between tow black holes 1.3 billion light years away. 

The Laser Interferometer Gravitational-Wave Observatory is made up of two detectors, this one in Livingston, La., and one near Hanford, Wash. The detectors use giant arms in the shape of an “L” to measure tiny ripples in the fabric of the universe. Credit: Caltech/MIT/LIGO Lab

The gravitational wave background is a random distribution of gravity waves that permeate the Universe and it is this that was detected in the European Pulsar Timing Array. The background is thought to occur from multiple, superimposed gravity waves generated from supermassive black hole binaries for example. The observation of the gravity wave background can give us a great opportunity to study the Universe at large much like the Cosmic Background Radiation. The achievement would not have been possible if it wasn’t for the European Pulsar Timing Array, the Indian PTA, the North American Nanohertz Observatory and the Parkes PTA. 

The full-sky image of the temperature fluctuations (shown as color differences) in the cosmic microwave background, made from nine years of WMAP observations. These are the seeds of galaxies, from a time when the universe was under 400,000 years old. Credit: NASA/WMAP

A pulsar timing array (PTA) consists of a network of galactic pulsars that are monitored and analysed to detect patterns in their pulse arrival times on Earth. Essentially, PTAs function as galaxy-sized detectors. While pulsar timing arrays have various applications, they are most well-known when employing an array of millisecond pulsars to detect and analyse the long-wavelength gravitational wave background.

The paper, authored by a team led by J.Antoniadis from the Institute of Astrophysics from Greece explore the implications of the common low frequency signal observed int he latest data released from the pulsar timing array systems. Assembling data from the four different datasets, the team look for a signal comprising only high quality data. 

The conclusion was unmistakable, yet more evidence for a gravity wave background. Over time, and with more Pulsar Timing Array projects, the low frequency gravity wave background will become increasingly distinctive. The mission now is to interpret the details of all these signals to maximise the opportunity to explore the Universe in this new way.

Source : The second data release from the European Pulsar Timing Array: IV. Implications for massive black holes, dark matter and the early Universe

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The giant outer planets haven’t always been in their current position. Uranus and Neptune for example are thought to have wandered through the outer Solar System to their current orbital position. On the way, they accumulated icy, comet-like objects. A new piece of research suggests as many as three kilomerer-sized objects crashed into them every hour increasing their mass. Not only would it increase the mass but it would enrich their atmospheres.

Uranus and Neptune are the two outermost planets in our Solar System. They differ from Jupiter and Saturn and share a number of characteristics based upon their composition. Atmospheres rich in ammonia and methane ice and also volumes of water distinguish them from the the other gas giants. Both have a distinctive blue hue to them, due to their composition  but Uranus is unique for its extreme axial tilt of 98 degrees. Observed from afar, it seems to orbit the Sun on its side. Neptune has wind speeds in excess of almost 2,000 kilometres. 

Image of Uranus from Webb

Observe the Solar System today and it seems a largely calm place but the Nice model (named after the location of the Cote d’Azure Observatory in Nice, France where it was developed) suggests the giant planets migrated from an initial location into their present position, long after the protoplanetary disk had dissipated. The idea became popular when it became clear that very long periods of time were required for Uranus and Neptune to form in their current location. 

In observations taken on 7 September 2021, researchers found that Neptune’s dark spot, which recently was found to have reversed course from moving toward the equator, is still visible in this image, along with a darkened northern hemisphere. There is also a notable dark, elongated circle encompassing Neptune’s south pole. The blue colour of both Neptune and Uranus is a result of the absorption of red light by the planets’ methane-rich atmospheres.

The model proposes that all the gas giants; Jupiter through to Neptune began their lives between 5 and 20 astronomical units from the Sun (one astronomical unit is equivalent to the average distance between Sun and Earth.) By comparison, Neptune is now at 30 astronomical units from Sun but some sort of catastrophic, chaotic event caused the planets to migrate out to their current positions. 

The simulations run by the team from the University of California suggests that it’s even possible that Neptune started out closer to the Sun than Uranus. The higher mass of Neptune seems to suggest this may be the case. Running through the simulations, the team estimate the amount of accretion on the planetesimals as they migrated out. 

The team announce that the ice giants seem to undergo bombardment from icy materials at an astonishing rate. The simulations showed that the extreme bombardment could have lasted for up to a million years with accretion rates of up to 3 planetesimals with a 1km radius every hour! This rate however seems to vary whether it is Uranus or Neptune and whether they switch position. In the simulations where Uranus is furthest from the Sun, both accrete at the same position, at between 22 and 26 astronomical units. Where Uranus is nearer to the Sun Neptune seems to offer some sort of shield and accretes the majority of planetesimals. 

It seems for now, the exact rates of accretion are still yet to be determined but we do know that the Solar System is far from peaceful and stable. Over many millions of years, the landscape of the Solar System has changed. It is fair to say that it will change again as the Sun ages but thankfully we are a few billion years off this yet. 

Source : Extensive Pollution of Uranus and Neptune’s Atmospheres by Upsweep of Icy Material During the Nice Model Migration

The post When Uranus and Neptune Migrated, Three Icy Objects Were Crashing Into Them Every Hour! appeared first on Universe Today.

The hunt for extrasolar planets has revealed some truly interesting candidates, not the least of which are planets known as “Hot Jupiters.” This refers to a particular class of gas giants comparable in size to Jupiter but which orbit very closely to their suns. Strangely, there are some gas giants out there that have very low densities, raising questions about their formation and evolution. This is certainly true of the Kepler 51 system, which contains no less than three “super puff” planets similar in size to Jupiter but is about one hundred times less dense.

These planets also go by the moniker “cotton candy” giants because their density is comparable to this staple confection. In a recent study, an international team of astronomers spotted another massive planet, WASP-193b, a fluffy gas giant orbiting a Sun-like star 1,232 light-years away. While this planet is roughly one and a half times the size of Jupiter, it is only about 14% as massive. This makes WASP-193b the second-lightest exoplanet observed to date. Studying this and other “cotton candy” exoplanets could provide valuable insight into how these mysterious giants form.

The research team consisted of astronomers from the Astrobiology Research Unit and the Space Sciences, Technologies, and Astrophysics Research (STAR) Institute at the Université de Liège, the Oukaimeden Observatory at Cadi Ayyad University, the Massachusetts Institute of Technology (MIT), the Instituto de Astrofísica de Andalucía (IAA-CSIC), the European Southern Observatory (ESO), the Center for Space and Habitability at the University of Bern, the Center for Computational Astrophysics, the Cavendish Laboratory, and the British aerospace company Space Forge. The paper that describes their findings recently appeared in the journal Nature Astronomy.

Artist’s impression of the Kepler 51 system. Credits: NASA/ESA/L. Hustak, J. Olmsted, D. Player and F. Summers (STScI)

The new planet was initially spotted by the Wide Angle Search for Planets (WASP), an international collaboration that operates two observatories (SuperWASP-North and WASP-South) and searches for exoplanets using the Transit Method (aka. Transit Photometry). Between 2006 and 2008, and again in 2011/2012, the WASP-South observatory detected periodic dips in WASP-193’s brightness. These dips were consistent with an exoplanet with an orbital period of 6.25 days and provided estimates of the planet’s size.

As Khalid Barkaoui, an MIT postdoctoral student and the study’s lead author, explained in an MIT News statement, “To find these giant objects with such a small density is really, really rare. There’s a class of planets called puffy Jupiters, and it’s been a mystery for 15 years now as to what they are. And this is an extreme case of that class… [WASP-193b] is so very light that it took four years to gather data and show that there is a mass signal, but it’s really, really tiny.”

To obtain estimates of the planet’s mass and density, astronomers relied on high-resolution spectra (aka. the Radial Velocity Method) from ground-based telescopes. Unfortunately, these attempts failed to yield accurate information because the planet was far too light to have any detectable effect on its star. In the end, Barkaoui and his team’s analysis allowed them to constrain its mass, which allowed them to estimate its density at about 0.059 grams per cubic centimeter. This is a far cry from Jupiter, which has a density of about 1.33 grams per cubic centimeter.

Said Francisco Pozuelos, a senior researcher at the Institute of Astrophysics of Andalucia and the co-lead author of the study:

“We don’t know where to put this planet in all the formation theories we have right now, because it’s an outlier of all of them. We cannot explain how this planet was formed, based on classical evolution models. Looking more closely at its atmosphere will allow us to obtain an evolutionary path of this planet. We were initially getting extremely low densities, which were very difficult to believe in the beginning. We repeated the process of all the data analysis several times to make sure this was the real density of the planet because this was super rare.”

Artist’s impression of the hot Jupiter exoplanet WASP-69b, which orbits its star so closely that its atmosphere is being blown into space. Credit: Adam Makarenko/W. M. Keck Observatory

The researchers suspect that WASP-193b is composed mostly of hydrogen and helium, like all gas giants, and that these form a hugely inflated atmosphere that extends tens of thousands of kilometers farther than Jupiter’s atmosphere. These findings cannot be explained by conventional theories of planet formation and evolution, which makes WASP-193b an ideal candidate for follow-up observations. In the near future, the team hopes to conduct follow-up studies using the James Webb Space Telescope (JWST) and a technique developed by MIT assistant professor Julien de Wit.

This technique allows astronomers to measure the temperature, composition, and pressure of an exoplanet’s atmosphere to various depths, which can be used to precisely determine the planet’s mass. “The bigger a planet’s atmosphere, the more light can go through,” de Wit says. “So it’s clear that this planet is one of the best targets we have for studying atmospheric effects. It will be a Rosetta Stone to try and resolve the mystery of puffy Jupiters.”

Further Reading: MIT, Nature Astronomy

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How did complex life emerge and evolve on the Earth and what does this mean for finding life beyond Earth? This is what a recent study published in Nature hopes to address as a pair of researchers investigated how plate tectonics, oceans, and continents are responsible for the emergence and evolution of complex life across our planet and how this could address the Fermi Paradox while attempting to improve the Drake Equation regarding why we haven’t found life in the universe and the parameters for finding life, respectively. This study holds the potential to help researchers better understand the criterion for finding life beyond Earth, specifically pertaining to the geological processes exhibited on Earth.

Here, Universe Today discusses this study with Dr. Taras Gerya, who is a Professor of Earth Sciences at the Swiss Federal Institute of Technology (ETH-Zurich) and co-author of the study, regarding the motivation behind the study, significant results, follow-up studies, what this means for the Drake Equation, and the study’s implications for finding life beyond Earth. So, what was the motivation behind this study?

Dr. Gerya tells Universe Today, “It was motivated by the Fermi Paradox (“Where is everybody?”) pointing out that the Drake Equation typically predicts that there are from 1000 to 100,000,000 actively communicating civilizations in our galaxy, which is too optimistic of an estimate. We tried to figure out what may need to be corrected in this equation to make the prediction with the Drake Equation more realistic.”

For the study, the research duo compared two types of planetary tectonic processes: single lid (also called stagnant lid) and plate tectonics. Single lid refers to a planetary body that does not exhibit plate tectonics and cannot be broken into separate plates that exhibit movement by sliding towards each other (convergent), sliding past each other (transform), or slide away from each other (divergent). This lack of plate tectonic activity is often attributed to a planetary body’s lid being too strong and dense to be broken apart. In the end, the researchers estimated that 75 percent of planetary bodies that exhibit active convection within their interiors do not exhibit plate tectonics and possess single lid tectonics, with Earth being the only planet that exhibits plate tectonics. Therefore, they concluded that single lid tectonics “is likely to dominate the tectonic styles of active silicate bodies in our galaxy”, according to the study.

Additionally, the researchers investigated how planetary continents and oceans contribute to the evolution of intelligent life and technological civilizations. They noted the significance of life first evolving in oceans due to them being shielded from harmful space weather with single-celled life thriving in the oceans for the first few billion years of Earth’s history. However, the researchers also emphasize how dry land provides a myriad of benefits for the evolution of intelligent life, including adaptations to various terrains, such as eyes and new senses, which contributed to animals evolving for speed to hunt among other biological assets that enabled life to adapt to the various terrestrial environments across the planet.

In the end, the researchers concluded dry land helped contribute to the evolution of intelligent life across the planet, including abstract thinking, technology, and science. Therefore, what were the most significant results from this study, and what follow-up studies are currently in the works or being planned?

Dr. Gerya tells Universe Today, “That very special condition (>500 million years coexistence of continents, oceans, and plate tectonics) is needed on a planet with a primitive life in order to develop an intelligent technological communicative life. This condition is very rarely realized: only <0.003-0.2 % of planets with any life may satisfy this condition.”

Dr. Gerya continues, “We plan to study water evolution in the planetary interior in order to understand how stability of surface ocean volume (implying stability of coexistence of oceans and continents) can be maintained for billions of years (like on Earth). We also plan to investigate the survival time of technological civilizations based on societal collapse models. We also started a project on the oxygenation state evolution of planetary interior and atmosphere in order to understand how oxygen-rich atmospheres (essential in particular for developing technological civilizations) can be formed on planets with oceans, continents and plate tectonics. Progress in these three directions is essential but will greatly depend on the availability of research funding.”

As noted, this study was motivated and attempts to improve the Drake Equation, which proposes a multivariable equation that attempts to estimate the number of active, communicative civilizations (ACCs) that exist in the Milky Way Galaxy. It was proposed by in 1961 Dr. Frank Drake to postulate several notions that he encouraged the scientific community to consider when discussing both how and why we haven’t heard from ACCs and reads as follows:

N = R* x fp x ne x fl x fi x fc x L

N = the number of technological civilizations in the Milky Way Galaxy who can potentially communicate with other worlds

R* = the average star formation rate in the Milky Way Galaxy

fp = the fraction of those stars with planets

ne = the average number of planets potentially capable of supporting life per star with planets

fl = the fraction of planets capable of supporting and developing life at some point in its history

fi = the fraction of planets that develop life and evolves into intelligent life

fc = the fraction of civilizations who develop technology capable of sending detectable signals into space

L = the length of time that technological civilizations send signals into space

According to the study, the Drake Equation estimates the number of ACCs range widely, between 200 to 50,000,000. As part of the study, the researchers proposed adding two additional variables to the Drake Equation based on their findings that plate tectonics, oceans, and continents have played a vital role in the development and evolution of complex life on Earth, which are as follows:

foc = the fraction of habitable exoplanets that possess notable continents and oceans

fpt = the fraction of habitable exoplanets that possess notable continents and oceans that also exhibit plate tectonics that have been functioning for at least 500 million years

Using these two new variables, the study provided new estimates for fi (chances of planets that develop life and evolve into intelligent life). So, what is the importance of adding two new variables to the Drake Equation?

Dr. Gerya tells Universe Today, “This allowed us to re-define and estimate more correctly the key term of the Drake equation fi – probability of a planet with primitive life to develop an intelligent technological communicative life. Originally, fi was (incorrectly) estimated to be very high (100%). Our estimate is many orders of magnitude lower (<0.003-0.2 %), which likely explains why we are not contacted by other civilizations.”

Additionally, when inputting these two new variables into the entire Drake Equation, the study estimates a far smaller number of ACCs at < 0.006 to 100,000, which is in stark contrast to the original estimates of the Drake Equation of 200 to 50,000,000. Therefore, what implications could this study have on the search for life beyond Earth?

Dr. Gerya tells Universe Today, “It has three key consequences: (1) we should not hope much that we will be contacted (probability of this is very low, in part because the life time of technological civilizations can be shorter than previously expected), (2) we should use remote sensing to look for planets with oceans, continents and plate tectonics (COPT planets) in our galaxy based on their likely distinct (CO2-poor) atmospheres and surface reflectivity signatures (due to the presence of oceans and continents), (3) we should take care about our own planet and civilization, both are extremely rare and must be preserved.”

This study comes as the search for life beyond Earth continues to gain traction, with NASA having confirmed the existence of 5,630 exoplanets as of this writing, with almost 1,700 being classified as Super-Earths and 200 being classified as rocky exoplanets. Despite these incredible numbers, especially since exoplanets first started being discovered in the 1990s, humanity has yet to detect any type of signal from an extraterrestrial technological civilization, which this study referred to as ACCs.

Arguably the closest we have come to receiving a signal from outer space was the Wow! signal, which was a 72-second radio blast received by Ohio State University’s Big Ear radio telescope on August 15, 1977. However, this signal has yet to be received since, along with a complete lack of signals at all. With this study, perhaps scientists can use these two new variables added to the Drake Equation to help narrow the scope of finding intelligent life beyond Earth.

Dr. Gerya concludes by telling Universe Today, “This research is part of an emerging new science – Biogeodynamics, which we try to support and develop. Biogeodynamics aims to understand and quantify relations between the long-term evolution of planetary interiors, surface, atmosphere, and life.”

How will these two new variables added to the Drake Equation help scientists find life beyond Earth in the coming years and decades? Only time will tell, and this is why we science!

As always, keep doing science & keep looking up!

The post Did Earth’s Multicellular Life Depend on Plate Tectonics? appeared first on Universe Today.

In a world that seems to be switching focus from the Hubble Space Telescope to the James Webb Space Telescope, Hubble still reminds us it’s there. Another amazing image has been released that shows the triple star system HP Tau, HP Tau G2, and HP Tau G3.  The stars in this wonderful system are young, HP Tau for example is so young that it hasn’t started to fuse hydrogen yet and is only 10 million years old!

Hubble was launched in 1990 and since then, has revolutionised our understanding of the Universe. It orbits Earth at an altitude of  around 547 kilometres and from that position has provided us stunning views of objects across the cosmos. It is about the size of a classic British double decker bus and at its core, a 2.4m mirror. The mirror collects incoming light from distant objects before directing it to one of a number of instruments that record and analyse it. 

NASA’s Hubble Space Telescope flies with Earth in the background after a 2002 servicing mission. Credit: NASA.

The image recently released shows a wonderful example of a reflection nebula 550 light years away in Taurus. These particular types of nebula are made up of interstellar dust that reflect light from nearby stars, unlike emission nebula which glow in their own right. They have a characteristic blue hue to them due to the reflective properties of the dust. Looking at the image you can easily imagine a hollowed out cavity in the nebula that has been carved by the young stars. 

The triple stars at the heart of the system, HP Tau, HP Tau G2 and HP Tau G3 are young hot stars. HP Tau is a type of variable star known as a T Tau star. They are a type of star that are less than 10 million years old and named after the first start of its type to be discovered in Taurus. Identification is usually achieved by studies of their optical variability and strong lines in their spectra from the chromosphere. Given their young age, they are generally found still being surrounded by the cloud of gas and dust they have formed out of.

The amount of light emitted by HP Tau varies with time however this particular type of star tends to have regular and sometimes random fluctuations. The jury is still out on the random variations but it may be the young nature of the stars leads to slightly chaotic processes as the stars begin to settle down. Perhaps material from an accretion disk still in the process of collapsing may dump material onto the star causing it to flare.

Take a good look at the image though and make sure to study the stunning patterns of the nebulosity. Remember the light that left this object has travelled for 550 years before entering the optics of the Hubble Space Telescope. When Hubble turned its attention to HP Tau it did so as part of an investigation into protoplanetary disks. These disks are seen in many young hot stars and are believed to be the progenitors to planetary systems around stars.

Source : Hubble Views the Dawn of a Sun-like Star 

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The world was much different in 1990 when NASA astronauts removed the Hubble Space Telescope from Space Shuttle Discovery’s cargo bay and placed it into orbit. The Cold War was ending, there were only 5.3 billion humans, and the World Wide Web had just come online.

Now, the old Soviet Union is gone, replaced by a smaller but no less militaristic Russia. The human population has ballooned to 8.1 billion. The internet is a fixture in daily life. We also have a new, more powerful space telescope, the JWST.

But the Hubble keeps delivering, as this latest image shows.

The lenticular galaxy NGC 4753 is about 60 million light-years away. Lenticular galaxies are midway between elliptical and spiral galaxies. They have large-scale disks but only poorly defined spiral arms. NGC 4753 sees very little star formation because like other lenticulars, it’s used up most of its gas. The fact that they contain mostly older stars makes them similar to elliptical galaxies.

Among lenticulars, NGC 4753 is known for the dust lanes surrounding its nucleus. Astronomers think that spirals evolve into lenticulars in dense environments because they interact with other galaxies and with the intergalactic medium. However, NGC 4753 is in a low-density environment. Its environment and complex structure make it a target for astronomers to test their theories of galaxy formation and evolution.

This Hubble image is the sharpest ever taken of NGC 4753, revealing its intriguing complexity and highlighting the space telescope’s impressive resolving power.

Astronomers think that NGC 4753 is the result of a merger with a dwarf galaxy over one billion years ago. The dwarf galaxy was gas-rich, and NGC 4753’s distinct dust rings probably accreted from the merger. NGC 4753’s powerful gravity then shaped the gas into the complex shapes we see in this image. Image Credit: ESA/Hubble & NASA, L. Kelsey

NGC 4763’s unique structure results from a merger with a dwarf galaxy about 1.3 billion years ago. The video below from NOIRlab explains what happened.

NGC 4753 also hosts two known Type 1a supernovae, which are important because they help astronomers study the expansion of the Universe. They serve as standard candles, an important rung in the cosmic distance ladder.

Galaxies like NGC 4753 may not be rare, but the viewing angle plays a key role in identifying them. Our edge-on view of the galaxy makes its lenticular form clear. We could be seeing others like it from different angles that obscure its nature.

This is a model of NGC 4753, as seen from various viewing orientations. From left to right and top to bottom, the angle of the line of sight to the galaxy’s equatorial plane ranges from 10° to 90° in steps of 10°. Although galaxies similar to NGC 4753 may not be rare, only certain viewing orientations allow for easy identification of a highly twisted disk. This infographic is a recreation of Figure 7 from a 1992 research paper.

If we were looking at NGC 4753 from the “top” down, its detailed dust lanes wouldn’t be obvious to us. But fortunately, we are.

And so is the Hubble.

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BepiColombo is a joint ESA/JAXA mission to Mercury. It was launched in 2018 on a complex trajectory to the Solar System’s innermost planet. The ESA reports that the spacecraft’s thrusters have lost some power.

BepiColombo’s mission is to complete a comprehensive investigation of Mercury’s magnetosphere, magnetic field, and internal and external structure. But travelling around in the inner Solar System is complicated, and the BepiColombo spacecraft will use more energy getting to Mercury than it takes to get to Pluto. The spacecraft will perform nine planetary flybys before reaching its destination at the end of 2025. BepiColombo has already performed one gravity assist at Earth, two at Venus, and five at Mercury. It’ll perform one more at Mercury in January 2025.

The Mercury Transfer Module (MTM) is the part of the spacecraft that delivers a pair of orbiters to Mercury. On April 26th, as the spacecraft was about to execute its next maneuver, the MTM didn’t deliver enough electrical power to its thrusters. A team working on it restored the thrust back to 90% on May 7th. But the MTM still isn’t deliver enough electricity to get back to 100% thrust.

Despite the power problems, the spacecraft is on track to complete its final Mercury flyby. A team is working to maintain the current power level and to understand how the diminished thrust will affect future maneuvers. They’re also working on restoring full power to the thrusters. To facilitate this, the mission’s flight control team at the European Space Operations Centre in Darmstadt, Germany, has arranged additional ground station passes.

BepiColombo employs a solar-electric propulsion system. Two 15-meter-long solar cells gather energy and deliver it to four ion thrusters that use xenon propellant. The thrusters are mounted on gimbals, making them aimable.

This schematic shows the components of BepiColombo’s solar-electric propulsion system minus the solar arrays. There are four T6 gridded ion thrusters mounted on gimbals, three tanks of xenon gas holding 1,400 kg of xenon gas, a high-pressure regulator, four flow control units and two power processing units. The system also includes several metres of high-voltage harness and piping required to connect this complex system together. Image Credit: ESA

BepiColombo consists of three separate spacecraft. The Mercury Transfer Module is kind of like a tugboat delivering two separate orbiters to Mercury. One of the orbiters is the Mercury Planetary Orbiter and it carries 11 scientific instruments, including cameras, several spectrometers, a magnetometer, and others. The other one is the Mercury Magnetospheric Orbiter, largely built by JAXA. It carries five groups of instruments, including one group that will study the plasma and neutral particles from the planet, its magnetosphere, and the solar wind.

This simple schematic shows the three separate spacecraft that combine to make the BepiColombo mission. Image Credit: ESA

The ESA says that they’ll share more information as it becomes available.

The post The BepiColombo Mission To Mercury is Losing Power appeared first on Universe Today.

Walking along on the surface of the Moon, as aptly demonstrated by the Apollo astronauts, is no easy feat.  The gravity at the Moon’s surface is 1/6th of Earth’s and there are plenty of videos of astronauts stumbling, falling and then trying to get up! Engineers have come up with a solution; a robotic arm system that can be attached to an astronauts back pack to give them a helping hand if they fall. The “SuperLimbs” as they have been called will not only aid them as they walk around the surface but also give them extra stability while carrying out tasks. 

The team of MIT engineers identified the problem when considering movement across the lunar surface and were inspired to innovate when they saw videos of astronauts struggling. They acknowledged that while the astronauts were physically very capable, the combination of bulky space suits and 1/6th gravity was recipe for disaster. If an astronaut becomes unbalanced then even though gravity is less, their inertia is the same and they will still fall. 

Sample collection on the surface of the Moon. Apollo 16 astronaut Charles M. Duke Jr. is shown collecting samples with the Lunar Roving Vehicle in the left background. Image: NASA

The solution they designed has been dubbed the Supernumerary Robotic Limbs can be built into their backpack and when needed, be extended. A prototype has been built and it includes a control system to operate the limbs. It was tested on a willing group of volunteers who donned suits to restrict mobility in an attempt to simulate the cumbersome space suits.

As the volunteers attempted to get up from sitting or lying position, the researchers looked at how they moved and how the restrictive suits limited their mobility. The suits were adjusted to more closely simulate a space suit. Using the suit to mimic the stiffness of a traditional suit they got as close as possible to real world testing. The movements of the team in the restricted suits was similar to normal movement but the effort was far less when the SuperLimbs were used. They also found that the volunteers used a common sequence of motions from one step in the process to the next. Using this information enabled them to build the control system to provide maximum efficiency. 

The control system that has been built is intelligent enough to detect the movement of the volunteers be they lying on their side, front or back. Having learned how people usually get up from such positions the system can detect the movement and provide suitable assistance to help. 

The team hope that the benefits of the system will go further than just helping the astronauts recover. By making it easier to get up, the astronauts will be able to conserve energy for other important tasks. With Artemis just around the corner and a return to human lunar exploration, it may well be that the ‘SuperLimbs’ will soon be a regular sight on human space explorers.

Source : Robotic “SuperLimbs” could help moonwalkers recover from falls

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Some Supermassive Black Holes (SMBHs) consume vast quantities of gas and dust, triggering brilliant light shows that can outshine an entire galaxy. But others are much more sedate, emitting faint but steady light from their home in the heart of their galaxy.

Observations from the now-retired Spitzer Space Telescope help show why that is.

It appears that every large galaxy has an SMBH at its heart. This is true of our Milky Way galaxy and of our closest galactic neighbour, Andromeda (M31.) Like all black holes, SMBHs draw material towards them that gathers in an accretion disk. As the material in the disk rotates and heats up, it emits light before it falls into the hole.

It turns out that both of those SMBHs are among the quiet eaters in the black hole population. Others are much more ravenous, consuming large amounts of matter in clumps and shining brightly for periods of time. Astrophysicists wonder what’s behind the difference.

Recent research published in The Astrophysical Journal has determined what’s happening in these different black holes. The title is “The Accretion Mode in Sub-Eddington Supermassive Black Holes: Getting into the Central Parsecs of Andromeda.” The lead author is Christian Alig, a post-doc student at the Max Planck Institute for Extraterrestrial Physics.

Andromeda (M31) is a close neighbour in cosmic terms. It’s about 780 kiloparsecs away, or about 2.5 million light years. It’s a sub-Eddington SMBH, meaning that it hasn’t reached the theoretical maximum accretion rate. Its proximity makes it an excellent target for observing and studying large-scale galactic structure, especially the nucleus. The nucleus is where most of the action is, dominated by an SMBH and containing a dense population of stars and a network of gas and dust. This research focuses on the gas and dust.

“This paper investigates the formation, stability, and role of the network of dust/gas filaments surrounding the M31 nucleus,” the authors write in their research. “The proximity of M31, 780 kpc, allows us to visualize in great detail the morphology, size, and kinematics of the filaments in ionized gas and dust.”

The researchers worked with images from the Hubble and Spitzer Space Telescopes. Using different filters, the telescope images revealed the shape and other characteristics of the network of gas and dust. “The appearance of the central region of M31 varies dramatically in the different mid-infrared bands, from a smooth, featureless bulge dominated by the old stellar population at 3.6 ?m to the distinct spiral dust filament structure that dominates the 8 ?m image,” the authors explain.

These images from the research show how different telescopes and filters can work together to reveal structure. The top row is Spitzer images of M31 at different wavelengths. Structure emerges successively with each image. The bottom right image is the 8 ?m image minus the 4.5 ?m image, which basically removes starlight. The middle right bottom image is a Hubble image showing H-alpha and ionized nitrogen. The bottom left image is a Hubble UV image, and the middle left is the same image with starlight removed. Image Credit: Alig et al. 2024.

The researchers found a circumnuclear dust ring around the galactic nucleus that measures between 0.5 and 1 kpc from the center (1,630 to 3,260 light-years.) Filaments of dust emanate from this ring, forming a spiral inside it. “Inside the ring, the dust filaments follow circularized orbits around the center, ending in a nuclear spiral in the central hundred parsecs,” the authors explain.

These images from the research successive zoom-ins at different wavelengths. In the middle image, a dotted white line outlines the circumnuclear ring in M31. The third image “… is a pure dust map of the central kiloparsec of M31,” the authors write. In the third image, an arrow shows the filament used as a reference in simulations. Image Credit: Alig et al. 2024.

After identifying structures in the telescope images, the researchers turned to simulations. They used hydrodynamical simulations to see what initial conditions made filaments and streamers of flowing gas move nearer to the SMBH. “By predicting the orbit and velocity of the filaments, we aim to infer the role of the nuclear spiral as a feeder of the M31 BH,” they explain.

The hydrodynamical simulations cover a wide area of the nucleus, from 900 parsecs to 6 parsecs from the SMBH in M31. The starting point for the simulations is the brightest and longest dust filament the team found in the images. In the image above, it’s marked with a white arrow. “The filament curves progressively toward the center as it approaches,” the researchers write. “It is also seen in the ionized gas <H-alpha and NII> though more diffuse, in the central few hundred parsecs.”

The simulations assume that the dust filament is made of dust infalling from the circumnuclear ring, though the researchers didn’t investigate how the dust made its way into the ring in the first place. The simulation began by injecting gas into the ring. The team let the simulation fun for millions of years to see how the gas behaves. “In the end, we needed about 200 Myr of simulation time to arrive at a configuration that best reproduces the observations,” the authors explain.

This figure shows snapshots from the simulation at different intervals from 17.5 million years to 156 million years. (a) and (b) don’t deviate much from an N-body simulation, but eventually, a ring takes shape. In (b,) the freshly injected material collides with the uppermost arc. That heats up the gas, creating a hot surrounding atmosphere shown in blue/pink. The stream crosses itself repeatedly after that and experiences friction from the atmosphere. (d) through (f) shows how the gas eventually circularizes into a ring shape. Image Credit: Alig et al. 2024.

“Friction at the inner edge of an elongated ring structure that forms in (e) causes thin filaments to spiral inward, eventually forming a small disk in the inner 100 pc, visible in (f),” the authors explain.

All of the team’s simulations arrived at similar results, even though they began with different parameters like initial angles, velocities, distances, and angle of injection. “Interestingly, due to the relatively good radial symmetry of the M31 potential in the inner 1 kpc, all simulations lead to very similar results,” the researchers explain.

The observations and images of M31’s inner region are in line with what astronomers find in other quiet galaxies. Those surveys “… reveal a common pattern in the dust morphology, formed by narrow, long dust filaments ending in a spiral in the central few hundred parsecs,” the authors write. The majority of low-luminosity galaxies in a 2003 study also have nuclear spirals that span several hundred parsecs.

Interestingly, high-accreting galaxies different than M31 also show a network of dust lanes and filaments, but their morphology is less organized. It often consists of one long filament that runs right across the nucleus. This could be the critical difference between the sedate SMBH in M31 and galaxies with much brighter black holes.

M31 and its ilk are fed a slow, steady diet of gas, which means their brightness is steady. But other galaxies are fed matter in larger clumps, which makes their brightness reach brilliant peaks, outshining all the stars in their galaxy. That’s the difference between gluttonous SMBHs and well-behaved ones.

“The hydrodynamical simulations show that the role of these filaments <in M31> is to transport matter to the center; however, the net amount that they transport to the center is small—a consequence of their extensive interaction with themselves, their surrounding atmosphere, and the ISM over a timescale of several million years,” the authors conclude. “We postulate that when dust/gas filaments in the central hundred parsecs of galaxies get to settle in a nuclear spiral configuration, a low accretion mode of the central BH will result.”

So galaxies with spiral patterns of gas in their nuclei have low accretion modes and lower, steadier luminosity. Galaxies without these patterns accrete more matter irregularly, and their luminosity surges.

One of the interesting things about this research is that it didn’t rely on new observations from new, powerful telescopes like the JWST. Instead, it relied on images from NASA’s Spitzer Space Telescope, which ended its mission in January 2020. It illustrates how modern telescopes and observatories generate massive amounts of data that scientists can utilize in different ways long after the telescope’s mission has ended.

“This is a great example of scientists reexamining archival data to reveal more about galaxy dynamics by comparing it to the latest computer simulations,” said study co-author Almudena Prieto, an astrophysicist at the Institute of Astrophysics of the Canary Islands and the University Observatory Munich. “We have 20-year-old data telling us things we didn’t recognize in it when we first collected it.”

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A long time ago, in two galaxies far, far away, two massive black holes merged. This happened when the Universe was only 740 million years old. A team of astronomers used JWST to study this event, the most distant (and earliest) detection of a black hole merger ever.

Such collisions are fairly commonplace in more modern epochs of cosmic history and astronomers know that they lead to ever-more massive black holes in the centers of galaxies. The resulting supermassive black holes can contain millions of billions of solar masses. They affect the evolution of their galaxies in many ways.

Using JWST and HST, astronomers have found behemoth black holes earlier and earlier in cosmic time, within the first billion years of the Universe’s history. That raises the question: how did they get so massive so fast? Black holes accrete matter as they grow, and for the most supermassive ones, their colliding galaxies are part of that matter-harvesting history.

What JWST Shows Us about Early Black Holes Merging

The most recent JWST observations focused on a system called ZS7. It’s a galaxy merger where two very early systems come together, complete with colliding black holes. This is not something astronomers can detect with ground-based telescopes. The merger itself lies quite far away. Plus, the expansion of the Universe stretches its light into the infrared part of the electromagnetic spectrum. That makes it inaccessible from Earth’s surface. However, infrared is detectable with JWST’s Near-infrared Spectrometer (NIRSpec). It can find signatures of mergers in the early Universe, according to astronomer Hannah Übler of the University of Cambridge in the United Kingdom.

Zeroing in on the ZS7 galaxy system and the colliding black holes. Courtesy: The field in which the ZS7 galaxy merger was observed by JWST. Courtesy ESA/Webb, NASA, CSA, J. Dunlop, D. Magee, P. G. Pérez-González, H. Übler, R. Maiolino, et. al

“We found evidence for very dense gas with fast motions in the vicinity of the black hole, as well as hot and highly ionized gas illuminated by the energetic radiation typically produced by black holes in their accretion episodes,” said Übler, who is lead author on a paper about the discovery. “Thanks to the unprecedented sharpness of its imaging capabilities, Webb also allowed our team to spatially separate the two black holes.”

Those black holes are pretty massive: one contains about 50 million solar masses. The other probably has about the same mass, but it’s hard to tell because it’s embedded in a dense gas region. The stellar masses of the galaxies puts them in about the same stellar-mass population as the nearby Large Magellanic Cloud, according to astronomer Pablo G. Pérez-González of the Centro de Astrobiología (CAB), CSIC/INTA, in Spain. “We can try to imagine how the evolution of merging galaxies could be affected if each galaxy had one supermassive black hole as large or larger than the one we have in the Milky Way”.

Other Implications of Black Hole Mergers at Cosmic Dawn

The analysis of the JWST observations reinforces the idea that mergers are an important way for black holes to grow. That’s particularly true in the early Universe, according to Ühler. “Together with other Webb findings of active, massive black holes in the distant Universe, our results also show that massive black holes have been shaping the evolution of galaxies from the very beginning.”

Many active galactic nuclei (AGN) in the very early Universe are associated with somewhat massive black holes. These are likely part of a general merger process in early epochs. Astronomers want to know when these mergers began. That would help them pinpoint the growth of the central supermassive black holes. Mergers of that kind are a likely route for the growth of black holes so early in cosmic time.

An artist’s impression of two merging black holes. Image: NASA/CXC/A. Hobart

That’s why astronomers are so anxious to spot them with JWST and future telescopes. They hold the key to understanding the evolution of galaxies and black holes in the infancy of the Universe. Uhler and her team members point this out in their paper, saying: “Our results seem to support a scenario of an imminent massive black hole merger in the early universe, highlighting this as an additional important channel for the early growth of black holes. Together with other recent findings in the literature, this suggests that massive black hole merging in the distant universe is common.”

Of course, these mergers don’t just generate light we can detect with JWST. They also generate very faint gravitational waves. But, there’s hope of detecting those waves with the upcoming Laser Interferometer Space Antenna (LISA). It will be in place in the 2030s and should be able to focus on the types of galaxy and black-hole mergers JWST is detecting today in infrared light.

For More Information

Webb Detects Most Distant Black Hole Merger to Date
GA-NIFS: JWST Discovers an Offset AGN 740 Million Years After the Big Bang

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The Sun has been vying for attention these last couple of weeks. First with the appearance of a fabulous complex sunspot region and then with a plethora of solar flares. On the 14th May, yet another was released, this time an X8.7 class flare from the same complex sunspot regions. It was significantly more powerful than the flare that set off the aurora displays which enchanted much of the planet but alas it was not pointing toward the Earth (

Europa has always held a fascination to me. I think it’s the concept of a world with a sub-surface ocean and the possibility of life that has inspired me and many others. In September 2022, NASAs Juno spacecraft made a flyby, coming within 355 kilometres of the surface. Since the encounter, scientists have been exploring the images and have identified regions where brine may have bubbled to the surface. Other images revealed possible, previously unidentified steep-walled depressions up to 50km wide, this could be caused by a free-floating ocean! 

Juno was launched to Jupiter on 5 August 2011. It took off from the Cape Canaveral site on board an Atlas V rocket and travelled around 3 billion kilometres. It arrived at Jupiter on 4 July 2016 and in September 2022 made its closest flyby of Europa. The frozen world is the second of the four Galilean satellites that were discovered by Galileo over 400 years ago. Visible in small telescopes, the true nature of the moon is only detectable by visiting craft like Juno. 

Artist’s impression of NASA’s Galileo space probe in orbit of Jupiter. Credit: NASA

During its close fly-by, one of the onboard cameras known as Juno-Cam took the highest resolution images of the moon since Galileo took a flyby in 2000. The images supported the long held theory that the icy crusts at the north and south poles are not where they used to be. Another instrument on board, known as the Stellar Reference Unit (SRU), revealed possible activity resembling plumes where brine may have bubbled to the surface. 

The ground track over Europa that was followed by Juno enabled imaging around the equatorial regions. The images revealed the usual, expected blocks of ice, walls, ridges and scarps but also found something else. Steep walled depressions that measured 20 to 50 kilometres across were also seen and they resembled large ovoid pits. 

One of Juno’s enormous solar panels, unfurled on Earth. NASA/JPL. SWrI

The observations of the meanderings of the north/south polar ice and the varied surface features all point towards an outer icy shell that is free-floating upon the sub surface ocean.  This can only happen if the outer shell is not connected to the rocky interior. When this happens, there are high levels of stress on the ice which then causes the fracture pattern witnessed. The images represent the first time such patterns have been seen in the southern hemisphere, the first evidence of true polar wandering. 

The images from the SRU surprisingly provided the best quality images. It was originally designed to detect faint light from stars for navigation. Instead, the team used it to capture images when Europa was illuminated by the gentle glow of sunlight reflected from Jupiter. It was quite a novel approach and allowed complex features to become far more pronounced than before. Intricate networks of ridges criss-crossing the surface were identified along with dark stains from water plumes. One feature in particular stood out, nicknamed ‘the Platypus’, it was a 37 kilometre by 67 kilometre region shaped somewhat like a platypus. 

Source : NASA’s Juno Provides High-Definition Views of Europa’s Icy Shell

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The tension between quantum mechanics and relativity has long been a central split in modern-day physics. Developing a theory of quantum gravity remains one of the great outstanding challenges of the discipline. And yet, no one has yet been able to do it. But as we collect more data, it shines more light on the potential solution, even if some of that data happens to show negative results.

That happened recently with a review of data collected at IceCube, a neutrino detector located in the Antarctic ice sheet, and compiled by researchers at the University of Texas at Arlington. They looked for signs that gravity could vary even a minuscule amount based on quantum mechanical fluctuations. And, to put it bluntly, they didn’t find any evidence of that happening.

To check for these minuscule fluctuations, they analyzed more than 300,000 detected neutrinos that IceCube had captured. IceCube is an impressive engineering feat, with thousands of sensors buried over one sq km in the ice. When one of the detectors is triggered by one of a hundred trillions of neutrinos passing through it every second, data on whether it was affected by any perturbations in the local gravity of that area can be collected.

Fraser discusses the neutrino detectors of IceCube.

Such massive data sets allowed for a very accurate reading—”over a million times more [accurate],” according to Dr. Benjamin Jones, one of over 300 physicists who worked on a paper detailing IceCube’s findings, which he described in a press release from the University of Texas at Arlington. Despite that, the researchers were still unable to find any evidence for those quantum fluctuations in the local gravitational field.

That’s not all bad news, though. Eliminating one possible explanation for quantum gravity could lead to work on others. Dr. Jones sees that prospect as he describes how his lab’s efforts are shifting to studying the mass of neutrinos themselves. Understanding more about these elusive particles certainly won’t hurt efforts to understand the overall physical model of the universe. Still, many scientists are likely disappointed by this newest failure to find a potential lead in the solution to a “theory of everything.”

For now, IceCube will keep collecting data, and scientists will continue to analyze it. But efforts to find a new theory of quantum gravity seem to be back at the theoretical drawing—which is a necessary step before they can be tested, no matter how fancy the detector itself is.

PBS Spacetime explains the idea behind quantum gravity.

Learn More:
UTA – UTA SCIENTISTS TEST FOR QUANTUM NATURE OF GRAVITY
IceCube Collaboration – Search for decoherence from quantum gravity with atmospheric neutrinos
UT – Scientists are Recommending IceCube Should be Eight Times Bigger
UT – IceCube Makes a Neutrino Map of the Milky Way

Lead Image:
IceCube Lab under the stars in the Antarctic.
Credit – IceCube/NSF

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NASA’s Juno spacecraft spies a tiny inner moon of Jupiter, Amalthea.

It’s tiny, but it’s there. By now, we’re all used to seeing amazing photos of Jupiter courtesy of NASA’s Juno mission on a routine basis. Many of these are processed by volunteer ‘citizen scientists,’ and they show the swirling cloud-tops of Jove courtesy of the spacecraft’s JunoCam in stunning detail.

Recently, JunoCam captured something special. Look closely at the side-by-side images of Jupiter from March 7th, 2024, and you’ll see a tiny speck transiting the Great Red Spot in the left lead image, that isn’t in the right. That’s the tiny inner moon Amalthea, just 84 kilometers across. The image was captured during the 59th perijove (close flyby) of the ‘King of the Planets,’ at a range of 265,000 kilometers distant (about two-thirds of the Earth-Moon distance).

Amalthea (arrowed) transits Jupiter. Credit: NASA/JPL-Caltech/SwRI/MSSS. Image processing by Gerald Eichstädt. Amalthea: An Origin Story

The elusive moon was discovered by prolific astronomer and observer E.E. Barnard on the night of September 9th, 1892. Barnard used the 91-centimeter diameter refractor telescope at the Lick observatory to spot the +14th magnitude moon, which never strays more than 30” from Jupiter (less than the apparent diameter of the planet) on its 12 hour orbit. Amalthea holds the distinction of being the last moon discovered via direct visual observation, and the first moon of Jupiter discovered since Galileo first spotted the four major Galilean moons in 1610. Today, Jupiter has 95 known moons, mostly captured asteroids. These were mainly discovered photographically and during spacecraft flybys.

One of Juno’s enormous solar panels, unfurled on Earth. NASA/JPL/SWrI

Like other small moonlets, Amalthea isn’t big enough to pull itself into a true sphere. Instead, like the Martian moons Phobos and Deimos, Amalthea is a potato-shaped, captured asteroid.

Amalthea: None More Red

The moon is also the reddest object in the solar system, and no doubt undergoes some serious tidal flexing thanks to the enormous gravitational field of nearby Jove. Amalthea is located 180,000 kilometers from Jove, just a little over 100,000 kilometers outside of Jupiter’s Roche limit radius. Any closer to Jove would tear Amalthea apart. The very innermost moon Metis just skims this limit.

Voyager 1’s color image of Amalthea from 1979. Credit: NASA/JPL

Voyagers 1 and 2 gave us the first blurry views of the moon. NASA’s only other Jupiter orbiter Galileo has provided us with the best images of Amalthea to date, with a flyby 374,000 kilometers distant on November 26, 1999. Those images reveal a misshapen world, not unlike Mars’ moon Deimos. From the surface of Amalthea, Jupiter would provide an amazing sight, spanning nearly half the sky at 42 degrees across.

The Galileo spacecraft’s best view of Amalthea. Credit: NASA/JPL Juno and the Present Status of the Mission

Juno launched from the Cape on August 5th, 2011, and arrived at Jupiter on July 5th, 2016. The mission probes the interior of Jupiter and its magnetic and radiation environment. Juno will answer key questions, including whether the planet has a solid core. Juno is the first solar-powered (as opposed to nuclear/plutonium-fueled) mission to the outer planets, meaning its nominal wide-ranging orbit was meant to avoid radiation damage to the solar panels. Engineers only allowed the spacecraft to venture in past the inner moons of Jupiter during the extended and final phase of the mission. Juno will operate until at least September 2025.

Two more missions are headed to Jupiter; ESA’s JUICE (Jupiter Icy moons Explorer) launched on April 14th 2023, and NASA’s Europa Clipper, set to launch in October 2024.

Jupiter, as seen from the surface of Amalthea. Credit: Stellarium

Watch for more amazing images courtesy of Juno, as the mission enters its final months and days.

The post New Photos Show Jupiter’s Tiny Moon Amalthea appeared first on Universe Today.

Despite the vast distance between us and Saturn’s gleaming moon Enceladus, the icy ocean moon is a prime target in our search for life. It vents water vapour and large organic molecules into space through fissures in its icy shell, which is relatively thin compared to other icy ocean moons like Jupiter’s Europa. Though still out of reach, scientific access to its ocean is not as challenging as on Europa, which has a much thicker ice shell.

The presence of large organic molecules isn’t very controversial. But they don’t necessarily signify that something alive lurks in its ancient, unseen ocean. Instead, hydrothermal processes could produce them. The complexity arises because hydrothermal processes are also linked to the emergence of life.

Understanding the abiotic processes that produce these molecules is important not just for Enceladus. It could serve as a baseline for understanding the results of a future mission to the frozen moon and any biosignatures it might detect.

New research in the journal Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences examines this issue. It’s titled “Laboratory characterization of hydrothermally processed oligopeptides in ice grains emitted by Enceladus and Europa.” The lead author is Dr. Nozair Khawaja from the Institute of Space Systems (IRS) at the University of Stuttgart.

Scientists postulate the life on Earth got started at hydrothermal events on the ocean floor. These vents provide mineral-rich fluids. At deep ocean vents under extreme pressure, these minerals can react with seawater to produce the building blocks of life.

This image shows a black smoker hydrothermal vent discovered in the Atlantic Ocean in 1979. It’s fueled from deep beneath the surface by magma that superheats the water, and the plume delivers minerals to the sea. Courtesy USGS.

“In research, we also speak of a hydrothermal field,” explains lead author Khawaja. “There is convincing evidence that conditions prevail in such fields that are important for the emergence or maintenance of simple life forms.”

Much of what we know about Enceladus comes from the Cassini mission. Scientists are still working with Cassini’s data even though it ended in 2017. Although much of the data was low resolution, it’s still valuable.

Professor Frank Postberg from the Freie Universität (FU) Berlin is one of the study’s co-authors. “In 2018 and 2019, we encountered various organic molecules, including some that are typically building blocks of biological compounds,” Postberg said. “And that means it is possible that chemical reactions are taking place there that could eventually lead to life.”

There’s a missing link between the hydrothermal vents and the molecules vented into space. Scientists aren’t certain if the vents are responsible for the molecules or in what way. Is life involved?

This image shows the detection of hydrothermally altered biosignatures on Enceladus. Image Credit: SWRI/NASA/JPL

To answer these questions, the researchers simulated an Enceladus hydrothermal vent in their laboratory.

“To this end, we simulated the parameters of a possible hydrothermal field on Enceladus in the laboratory at the FU Berlin,” said lead author Khawaja. “We then investigated what effects these conditions have on a simple chain of amino acids.” Amino acids are the basic building blocks of proteins and the basis of all Earth life. There are hundreds of them, and 22 of them are in all living cells. They’re the precursors to proteins and they show that life on Earth is all connected.

The researchers subjected amino acids to conditions thought to persist at Encledadus’ ocean floor. “Here, we present results from our newly established facility to simulate the processing of ocean material within the temperature range 80–150°C and the pressure range 80–130 bar, representing conditions suggested for the water-rock interface on Enceladus,” they write in their paper. Under those conditions, the chains of amino acids behaved characteristically.

But that’s in a lab. Can we devise a space probe that can detect these types of changes on Enceladus? The changes themselves are obscured, but do they produce byproducts or markers that are emitted into space?

Cassini’s Cosmic Dust Analyzer (CDA) detected the organic molecules in Enceladus’ plumes by watching collisions between rapidly moving particles that shatter molecules and vapourize their contents. Some particles, stripped of their electrons, become positively charged and are attracted to a negative electrode on the instrument. The less massive they are, the faster they reach the electrode.

By combining a large amount of this type of data, the CDA revealed a lot about the original molecules.

But this can’t be replicated in a lab.

“Instead, we employed an alternative measurement method called LILBID for the first time on ice particles containing hydrothermally altered material,” Khawaja explains. LILBID stands for laser-induced liquid beam ion desorption, a different type of mass spectrometry than the CDA performs. Though the method is different, it produces results similar to Cassini’s CDA instrument.

“This delivers very similar mass spectra to the Cassini instrument. We used this to measure an amino acid chain before and after the experiment. In the process, we came across characteristic signals that were caused by the reactions in our simulated hydrothermal field,” Khawaja said.

Specifically, the researchers examined the hydrothermal processing of the triglycine (GGG) peptide. GGG is a tripeptide, the most common one. Scientists often use GGG to study amino acids, peptides, and proteins, analyzing the molecular interactions and physicochemical parameters of all three.

“Differences observed between mass spectra of hydrothermally processed and unprocessed triglycine can be regarded as a spectral fingerprint to identify processed GGG in ice grains from icy moons in the solar system,” the authors wrote in their research.

These two panels from the research compare the mass spectra of hydrothermal unprocessed triglycine (left) to hydrothermally processed triglycine (right.) There are some clear differences between the two. Image Credit: Khawaja et al. 2024.

“This delivers very similar mass spectra to the Cassini instrument. We used this to measure an amino acid chain before and after the experiment. In the process, we came across characteristic signals that were caused by the reactions in our simulated hydrothermal field,” Khawaja said.

The researchers intend to repeat this experiment with other organic molecules under extended geophysical conditions in Enceladus’ ocean. “With this new laboratory setup, we will simulate a range of hydrothermal conditions, from the high pressures and temperatures associated with greater depths into the core, to the milder conditions in the ocean water near the water-rock interface,” the authors write in their paper.

The results will allow them to search through Cassini’s data for similar markers. It can also work for future missions to Enceladus and would be further proof of hydrothermal activity on the frozen ocean moon.

If scientists can confirm hydrothermal vents on Enceladus, the excitement that moon generates will only increase.

The post Linking Organic Molecules to Hydrothermal Vents on Enceladus appeared first on Universe Today.

Astronomers were surprised in 1937 when a star in a binary pair suddenly brightened by 1,000 times. The pair is called FU Orionis (FU Ori), and it’s in the constellation Orion. The sudden and extreme variability of one of the stars has resisted a complete explanation, and since then, FU Orionis has become the name for other stars that exhibit similar powerful variability.

The star in question is called Orionis North, and it’s the central star of the pair. Astronomers see its brightening behaviour in old stars but not in young stars like FU Ori. The young star is only about 2 million years old.

Astronomers working with ALMA (Atacama Large Millimetre-submillimetre Array) have discovered the reason behind Fu Ori’s variability. They’ve published their research in the Astrophysical Journal. It’s titled “Discovery of an Accretion Streamer and a Slow Wide-angle Outflow around FU Orionis,” and the lead author is Antonio Hales, deputy manager of the North American ALMA Regional Center and scientist with the NRAO.

Here’s what scientists do know about FU Ori (FUor) stars and their variability. They brighten when they attract gas gravitationally into an accretion disk. Too much mass at once can destabilize the disk, and as material falls into the star, it brightens. But what they didn’t understand was why and how this happened.

“FU Ori has been devouring material for almost 100 years to keep its eruption going. We have finally found an answer to how these young outbursting stars replenish their mass,” explained lead author Hales. “For the first time we have direct observational evidence of the material fueling the eruptions.”

ALMA is the world’s largest radio telescope. It’s an interferometer with 66 separate antennae, which can be moved across the ground to give the observatory a ‘zoom-in’ effect. This powerful observatory has driven a lot of astronomical science.

In this research, ALMA identified a long streamer of carbon monoxide that appears to be falling into FU Ori. The researchers don’t think this streamer has enough material to sustain the star’s current outburst. But it could be the remnant from a past episode. “It is possible that the interaction with a bigger stream of gas in the past caused the system to become unstable and trigger the brightness increase,” explained Hales.

This figure from the research shows 12CO and 13CO emissions as detected by ALMA. The colours denote velocity. The CO streamer of infalling gas is labelled. “The elongated feature has a connection neither to the larger-scale molecular outflow nor to the inner disk rotation and is more similar to accretion streamers recently reported around young stellar objects,” the authors explain. Image Credit: Hales et al. 2024.

The current outburst creates strong stellar winds that interact with a leftover envelope of material from the star’s formation. The wind shocks the envelope, sweeping up carbon monoxide with it. The CO is what ALMA detected.

Artist’s impression of the large-scale view of FU~Ori. The image shows the outflows produced by the interaction between strong stellar winds powered by the outburst and the remnant envelope from which the star formed. The stellar wind drives a strong shock into the envelope, and the CO gas swept up by the shock is what the new ALMA revealed. The inset image is an artist’s impression of the streamer of CO feeding mass into FU Ori. Image Credit: NSF/NRAO/S. Dagnello

ALMA’s ability to operate in different configurations and wavelengths played a role in this work. It allowed the team to detect different types of emissions and to detect the mass flowing into FU Ori. They compared the observations to models of mass flow and accretion streamers. “We compared the shape and speed of the observed structure to that expected from a trail of infalling gas, and the numbers made sense,” said Aashish Gupta, a Ph.D. candidate at European Southern Observatory (ESO). Gupta is a co-author of this work, and he developed the methods used to model the accretion streamer.

This image from the research shows the model results (green line) overlain on ALMA data. The streamer modelling closely matches the data. “The fitting results suggest that the morphology and the velocity profile of the observed streamer emission can be well represented as a trail of infalling gas,” the authors write in their published research. Image Credit: Hales et al. 2024.

The researchers measured the amount of material flowing into FU Ori through the streamer. About 0.07 Jupiter Masses per Myr?1 flow into the young star. Jupiter is about 318 times more massive than Earth. This means that FU Ori’s infall streamer rate is lower than infall around other Class 0 protostars. “This would suggest that the observed streamer will require ?100 Myr to replenish disk masses, which is at least an order of magnitude greater than the typical disk lifetimes,” the authors point out.

The infall streamer and its effect on the star are complex. Not enough material comes in via the streamer to trigger the outbursts. “The streamer needs to be more massive to sustain FU Ori’s outburst accretion rates (by several orders of magnitude). The estimated streamer mass infall rate is not even sufficiently massive to sustain quiescent stellar accretion rates,” the authors explain.

Instead, the infalling material causes disk instability, which in turn delivers enough material to FU Ori to trigger outbursts. “Anisotropic infall, cloudlet capture events, the inhomogeneous delivery of material, and the building up of material around dust traps can all lead to the disk instabilities that could trigger accretion outbursts,” Hales and his co-authors write. They can’t say for sure if this is what’s happening. That would require more modelling, which is outside the scope of this work.

ALMA also spotted another streamer of slow-moving CO. This one is coming from the star rather than falling into it. Hales and his colleagues think this streamer is similar to streamers coming from other young protostellar objects and isn’t related to the brightening. “The ALMA observations reveal the presence of large-scale, wide-angle bipolar outflows for the first time around the class prototype FU Ori,” the researchers write in their paper.

Curiously, astronomers have detected these outflows from other FUor stars but never at FU Ori itself. It’s coming from Fu Ori North, the star that experiences the powerful brightening.

“Prior searches for molecular outflows around FUors, mainly using single-dish telescopes, reported outflowing material from many FUors but failed to detect flows emerging from the FUor class prototype,” the researchers write in their paper. “These nondetections instigated the belief that there were no molecular outflows around the FU Ori system. Our discovery ends the mystery by clearly demonstrating the presence of a molecular outflow from FU Ori itself.”

Understanding young stars is critical because their behaviour governs planet formation. FU Ori’s brightening could have a defining effect on the planets that form around the star.

“By understanding how these peculiar FUor stars are made, we’re confirming what we know about how different stars and planets form,” Hales explained. “We believe that all stars undergo outburst events. These outbursts are important because they affect the chemical composition of the accretion discs around nascent stars and the planets they eventually form.”

For the authors, their research demonstrates how the powerful ALMA observatory makes a unique contribution to astronomical research. “These results demonstrate the value of multiscale interferometric observations to enhance our understanding of the FU Ori outbursting system and provide new insights into the complex interplay of physical mechanisms governing the behaviour of FUor-type and the many other kinds of outbursting stars,” the authors conclude.

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Planetary scientists perk up whenever methane is mentioned. Methane is produced by living things on Earth, so it’s considered to be a potential biosignature elsewhere. In recent years, MSL Curiosity detected methane coming from the surface of Gale Crater on Mars. So far, nobody’s successfully explained where it’s coming from.

NASA scientists have some new ideas.

Ever since Curiosity landed on Mars in 2012, it’s been sensing methane. But the methane displays some odd characteristics. It only comes out at night, it fluctuates with the seasons, and sometimes, the amount of methane jumps to 40 times more than the regular level.

The ESA’s ExoMars Trace Gas Orbiter entered a science orbit around Mars in 2018, and scientists fully expected it to detect methane in the planet’s atmosphere. But it didn’t, and it has never been detected elsewhere on Mars’ surface.

If life was producing the methane, it appears to be restricted to the subsurface under Gale Crater.

There’s no convincing evidence that life exists on Mars. It may have in the past, and it’s possible that some extant life clings to a tenuous existence in subsurface brines or something. But we lack evidence, so life is basically ruled out as the methane source. Especially since the evidence shows life would have to be under Gale Crater and nowhere else.

Scientists have been trying to determine the source of methane, but so far, they haven’t come up with a specific answer. It has something to do with subsurface geological processes involving water, most likely.

This image illustrates possible ways methane might get into Mars’ atmosphere and also be removed from it: microbes (left) under the surface that release the gas into the atmosphere, weathering of rock (right), and stored methane ice called a clathrate. Ultraviolet light can work on surface materials to produce methane as well as break it apart into other molecules (formaldehyde and methanol) to produce carbon dioxide. Credit: NASA/JPL-Caltech/SAM-GSFC/Univ. of Michigan

“It’s a story with a lot of plot twists,” said Ashwin Vasavada, Curiosity’s project scientist at NASA’s Jet Propulsion Laboratory in Southern California, which leads Curiosity’s mission.

Alexander Pavlov is a planetary scientist at NASA’s Goddard Space Flight Center who leads a group of NASA scientists studying the Martian Methane Mystery. In recent research, they suggested that the methane is stored underground. They didn’t explain what produced it, but they showed that methane can be sealed underground by salt solidified in the Martian regolith.

This figure from research published in 2024 illustrates how a salt cap could form and trap methane under the Martian surface. There’s strong evidence of subsurface water on Mars, and it can migrate to the surface and evaporate. Some of the salt in the ground is transported to the surface with the water. Once the water or ice is gone, the salt is left behind in the upper few centimetres of soil. The researchers hypothesized that the salt can become cemented into the same type of duricrust that the InSight lander struggled with. Image Credit: Pavlov et al. 2024.

They suggested that the methane could be released from its subsurface reservoir by the weight of the Curiosity rover itself. The rover’s weight could break the salt seal and release methane in puffs. That’s an interesting proposition, but it doesn’t explain the seasonal and diurnal fluctuations. That makes sense since the Gale Crater is one of only two regions where a rover is working. The other is Jezero Crater, where the Perseverance Rover is working, but it doesn’t have a methane detector. (Neither will the ESA’s Rosalind Franklin rover, which is scheduled to land on Mars in 2029.)

The research group addressed those fluctuations by suggesting that seasonal and daily heating could also break the seal and release methane.

Their potential explanations stem from research Pavlov conducted in 2017. He grew bacteria called halophiles, which grow in salty conditions, in simulated Martian permafrost. The simulated soil was infused with salt, replicating conditions on much of Mars. The microbe growth was inconclusive, but the researchers noticed something else. As the salty ice sublimated, a layer of solidified salt remained, forming a crust.

“We didn’t think much of it at the moment,” Pavlov said.

But he remembered it when MSL Curiosity detected an unexplained burst of methane on Mars in 2019.

“That’s when it clicked in my mind,” Pavlov said. Then, he and a team of researchers began testing conditions that could form the hardened salt seals and then break them open.

Perchlorate is a chemical salt that’s widespread on Mars. Pavlov and his fellow researchers recreated different simulated Martian permafrosts with varying amounts of perchlorate. Inside a Mars simulation chamber, they subjected the samples to different temperatures and atmospheric pressures to see if they would form seals.

In their experiments, they used neon as a methane analog and injected it under the soil. Then, they measured the gas pressure below and above the soil. They found that the pressure was higher under the soil, meaning the gas was being trapped by the salty permafrost. Furthermore, they found that seals formed in samples containing as little as 5% or 10% perchlorate, and they formed within 3 to 13 days. Those are compelling results.

This image shows one of the Mars analog samples with a hardened crust of salt sealing the surface. The lighter colour is where the sample has been scratched. The lighter colour indicates drier soil, and once it was exposed to air outside the Mars Chamber, it quickly absorbed moisture and turned brown. Image Credit: Pavlov et al. 2018.

While 5-10% perchlorate doesn’t sound like much, it’s actually a higher concentration than in Gale Crater, where the methane has been detected. But perchlorate isn’t the only salt in Martian regolith. It also contains sulphates, another type of salt mineral. Pavlov says he and his team will test sulphates next for their ability to form a seal.

The Martian Methane Mystery is commanding a lot of attention. It’s a juicy mystery, and once it’s solved, our understanding of methane as a biosignature or false positive will be much improved. NASA’s 2022 Planetary Mission Senior Review recommended that the issue of methane production and destruction at Mars be investigated further.

The type of work that Pavlov and his colleagues are doing is important, but it’s being held back. Pavlov says that they need more consistent methane measurements. The problem is that Curiosity’s SAM (Sample Analysis at Mars) instrument, which senses the methane, is busy with other tasks. It only checks for methane a few times per year. It’s mostly occupied with drilling samples and testing them, a critical and time-consuming part of the rover’s mission.

The Tunable Laser Spectrometer is one of the tools within the Sample Analysis at Mars (SAM) laboratory on NASA’s Curiosity Mars rover. By measuring the absorption of light at specific wavelengths, it measures concentrations of methane, carbon dioxide and water vapour in Mars’ atmosphere. (Image Credit: NASA/JPL-Caltech)

“Methane experiments are resource intensive, so we have to be very strategic when we decide to do them,” said Goddard’s Charles Malespin, SAM’s principal investigator.

Curiosity’s mission wasn’t designed to measure methane fluctuations. In 2017, NASA said its SAM instrument only sampled the atmosphere 10 times in 20 months. That’s a very inconsistent sample that leaves lots of unanswered questions.

Scientists think another mission is needed to advance their understanding of Martian methane. Rather than one sensor taking irregular methane readings from one location, we need multiple testing stations on the surface that regularly monitor the atmosphere. Nothing like it is in the works.

“Some of the methane work will have to be left to future surface spacecraft that are more focused on answering these specific questions,” Vasavada said.

The post New Answers for Mars’ Methane Mystery appeared first on Universe Today.

Mention the Milky Way and most people will visualise a great big spiral galaxy billions of years old. It’s thought to be a galaxy that took shape billions of years after the Big Bang. Studies by astronomers have revealed that there are the echo’s of an earlier time around us. A team of astronomers from MIT have found three ancient stars orbiting the Milky Way’s halo. The team think these stars formed when the Universe was around a billion years old and that they were once part of a smaller galaxy that was consumed by the Milky Way. 

The Milky Way is our home galaxy within which our entire Solar System and an estimated 400 billion other stars. It measures 100,000 light years from sided to side and is home to almost everything else we can see in the sky with our naked eyes. On a clear dark night we can see the combined light from all the stars in the galaxy forming a wonderful band of hazy light arching across the sky from horizon to horizon. If you could view the Galaxy from the outside its broad shape would resemble two fried eggs stuck back to back.

The story of the discovery takes us back to 2022 during a new Observational Stellar Archaeology course at MIoT when students were learning how they can analyse ancient stars. They then applied them to stars that have not yet been analysed. They worked with data from the 6.5m Magellan-Clay telescope at Las Campanas Observatory and were searching for stars that had formed soon after the Big Bang. At this time in the evolution of the Universe, there was mostly hydrogen and helium with trace amounts of strontium and barium. The team therefore searched for stars with spectra indicating these elements. 

Precision manufacturing is at the heart of the Giant Magellan Telescope. The surface of each mirror must be polished to within a fraction of the wavelength of light. Image: Giant Magellan Telescope Organization

They honed in on just three stars that had been observed in 2013 and 2014 but they had not been previously analysed so were a great study for the students. On completion of their analysis (which took several hundred hours at a computer), the team identified that the stars had very low levels of strontium and barium as predicted if they were ancient stars. The stars they studied were estimated at having formed between 12 and 13 billion years ago. What wasn’t clear was the origin of the stars.  How did they come to be in the Milky Way given that it was relatively new and young. 

The team decided to analyse the orbital characteristics of the stars to see how they moved. The stars were all in different locations through the Milky Way’s halo and all thought to be about 30,000 light years from Earth. Comparing the motion with data from the Gaia astrometric satellite they discovered the stars were going in the opposite direction to the majority of other stars in the Milky Way. We call this retrograde motion and it suggests the stars came from somewhere else, not having formed with the Milky Way. The chemical signatures of the stars coupled with their motion give strong credibility to the liklihood these ancient stars are not native to the Milk Way.

Now they have developed there approach to identify ancient stars, the students are keen to expand their search to see if any others can be located. However with 400 billion stars in the Milky Way, a slightly more efficient method needs to be found. 

Source : MIT researchers discover the universe’s oldest stars in our own galactic backyard

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If you watch astronauts in space then you will know how they seem to float around their spaceship. Spaceships in orbit around the Earth are in free-fall, constantly falling toward surface fo the Earth with the surface constantly falling away from it. Any occupant is also in free-fall but living like this causes muscle tone to degrade slowly. One solution is to generate artificial gravity through acceleration in particular a rotating motion. A new paper makes the case for a rotating space station and goes so far that it is achievable now. 

Acceleration is a change in either direction or speed. In a lift you can feel a deceleration as you feel heavier when the lift slows at the bottom of its descent. It would certainly be possible to generate an artificial force of gravity in a box travelling through space if it constantly accelerates. This would produce a sense of a floor and pin the occupants to the rear wall. This is however, a fairly inefficient way to produce gravity as significant amounts of fuel would be required to continually accelerate the box. 

A recent paper published in Science Direct by lead author Jack J.W.A. van Loon shows how a spaceship that continuously rotates will produce an artificial gravity on the inner skin of the outer shell. The benefits to such an approach are significant; improved crew health and wellbeing, safety improvements, cost reductions and the simplification of numerous flight operations.  

There are many ways that astronauts attempt to limit the impacts on health from micro-gravity. Treadmills with straps to pull the astronauts down onto the running platform are just one of the ways they attempt to keep bones and muscles in tip top condition. If they don’t then bone and muscle density declines. Research has sown that for every month in space, an astronauts’ weight bearing bones become 1% less dense. Muscles wean too and this causes problems on their return to Earth and ‘normal gravity’ so it is a vitally important part of their routine. 

ESA astronaut Alexander Gerst gets a workout on the Advanced Resistive Exercise Device (ARED). Credit: NASA

The team go on to explore a number of options such as a short arm centrifuge. These would certainly generate artificial gravity but the short arm would mean the gravity gradient from foot to head of occupants would be too great and have a negative health impact. An alternate solution, and more efficient feasible solution is to build a large rotating spacecraft. Such a craft would have benefits for long term missions such as trips to Mars but also benefit those in orbit around Earth for months on end. Savings would be impressive as significant investments are made combatting the effect of microgravity.

The team discuss what would be needed to simulate and Earth-like 1g environment on a spacecraft. A donut shaped spacecraft with a 25 m radius would need to be spun 6 times per minute to generate a 1g environment. Larger spacecraft could be revolved at a slower rate. Doing so not only benefits the astronauts but nearly every aspect of life in space would be enhanced and safer; liquids would behave in a normal way, flames too would behave in a more familiar way, toilets can of a more normal design as can self care systems. The benefits are significant so I don’t think it will be long before we see astronauts walking around in revolving spacecraft enjoying the luxury of normal gravity again. 

Source : Benefits of a rotating – Partial gravity – Spacecraft

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When stars exhaust their hydrogen fuel at the end of their main sequence phase, they undergo core collapse and shed their outer layers in a supernova. Whereas particularly massive stars will collapse and become black holes, stars comparable to our Sun become stellar remnants known as “white dwarfs.” These “dead stars” are extremely compact and dense, having mass comparable to a star but concentrated in a volume about the size of a planet. Despite being prevalent in our galaxy, the chemical makeup of these stellar remnants has puzzled astronomers for years.

For instance, white dwarfs consume nearby objects like comets and planetesimals, causing them to become “polluted” by trace metals and other elements. While this process is not yet well understood, it could be the key to unraveling the metal content and composition (aka. metallicity) of white dwarf stars, potentially leading to discoveries about their dynamics. In a recent paper, a team from the University of Colorado Boulder theorized that the reason white dwarf stars consume neighboring planetesimals could have to do with their formation.

The research team consisted of Tatsuya Akiba, a Ph.D. candidate at UC Boulder with the Joint Institute for Laboratory Astrophysics (JILA) at UC Boulder. He was joined by Selah McIntyre, an undergraduate student in the Department of Chemistry, and Ann-Marie Madigan, a JILA Fellow and a professor in the Department of Astrophysical and Planetary Sciences. Their research was reported in a paper titled “Tidal Disruption of Planetesimals from an Eccentric Debris Disk Following a White Dwarf Natal Kick,” which recently appeared in The Astrophysical Journal.

Planetesimal orbits around a white dwarf. Initially, every planetesimal has a circular, prograde orbit. The kick forms an eccentric debris disk with prograde (blue) and retrograde orbits (orange). Credit: Steven Burrows/Madigan group

Despite their prevalence in our galaxy, the chemical makeup of white dwarfs has puzzled astronomers for years. The presence of heavy metal elements like silicon, magnesium, and calcium on the surfaces of many of these stellar remnants defies what astronomers consider conventional stellar behavior. “We know that if these heavy metals are present on the surface of the white dwarf, the white dwarf is dense enough that these heavy metals should very quickly sink toward the core,” said Akiba in a recent JILA press release. “So, you shouldn’t see any metals on the surface of a white dwarf unless the white dwarf is actively eating something.”

Madigan’s research group at JILA focuses on the gravitational dynamics of white dwarfs and how these affect surrounding material. For their study, the team created computer models that simulated a white dwarf experiencing a rare phenomenon known to occur during its formation. This consisted of an asymmetric mass loss caused by a “natal kick” that altered its motion and the dynamics of the surrounding material. As Professor Madigan explained:

“Simulations help us understand the dynamics of different astrophysical objects. So, in this simulation, we throw a bunch of asteroids and comets around the white dwarf, which is significantly bigger, and see how the simulation evolves and which of these asteroids and comets the white dwarf eats. Other studies have suggested that asteroids and comets, the small bodies, might not be the only source of metal pollution on the white dwarf’s surface. So, the white dwarfs might eat something bigger, like a planet.”

In 80% of their test runs, the team observed that the orbits of comets and planetesimals within 30 to 240 AU (the distance between the Sun and Neptune and well into the Kuiper Belt) of the star became elongated and aligned. They also found that in about 40% of their simulations, the consumed planetesimals came from retrograde orbits. Lastly, they extended their simulations to 100 million years after formation and found that these planetesimals still had elongated orbits and moved as one coherent unit.

Artist’s illustration of crystals forming within a white dwarf. Credit: University of Warwick/Mark Garlick

These new findings also shed light on the origin, chemistry, and future evolution of stars, including our Solar System. In about 5 billion years, our Sun will exit its main sequence phase and grow to become a Red Giant. Roughly 2 billion years later, it will blow off its outer layers in a supernova, leaving behind a white dwarf remnant. Looking ahead, the researchers hope to take their simulations to greater scales to examine how white dwarfs interact with larger planets. These simulations could reveal what will become of the outer planets in our Solar System once our Sun is in its “dead” phase. Said Madigan:

“This is something I think is unique about our theory: we can explain why the accretion events are so long-lasting. While other mechanisms may explain an original accretion event, our simulations with the kick show why it still happens hundreds of millions of years later. The vast majority of planets in the universe will end up orbiting a white dwarf. It could be that 50% of these systems get eaten by their star, including our own solar system. Now, we have a mechanism to explain why this would happen.”

Further Reading: JILA, AJL

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