Tag Archives: #solarsystem

Sculpted By Starlight: A Meteorite Witness To The Solar System’s Birth (Cosmology)

Researchers use unusual meteorite to gain insight into our solar system’s past, present

In 2011, scientists confirmed a suspicion: There was a split in the local cosmos. Samples of the solar wind brought back to Earth by the Genesis mission definitively determined oxygen isotopes in the sun differ from those found on Earth, the moon and the other planets and satellites in the solar system.

Early in the solar system’s history, material that would later coalesce into planets had been hit with a hefty dose of ultraviolet light, which can explain this difference. Where did it come from? Two theories emerged: Either the ultraviolet light came from our then-young sun, or it came from a large nearby star in the sun’s stellar nursery.    

Ryan Ogliore
Ogliore © WUSTL

Now, researchers from the lab of Ryan Ogliore, assistant professor of physics in Arts & Sciences at Washington University in St. Louis, have determined which was responsible for the split. It was most likely light from a long-dead massive star that left this impression on the rocky bodies of the solar system. The study was led by Lionel Vacher, a postdoctoral research associate in the physics department’s Laboratory for Space Sciences.

Their results are published in the journal Geochimica et Cosmochimica Acta.

“We knew that we were born of stardust: that is, dust created by other stars in our galactic neighborhood were part of the building blocks of the solar system,” Ogliore said.

“But this study showed that starlight had a profound effect on our origins as well.”

Tiny time capsule

All of that profundity was packed into a mere 85 grams of rock, a piece of an asteroid found as a meteorite in Algeria in 1990, named Acfer 094. Asteroids and planets formed from the same presolar material, but they’ve been influenced by different natural processes. The rocky building blocks that coalesced to form asteroids and planets were broken up and battered; vaporized and recombined; and compressed and heated. But the asteroid that Acfer 094 came from managed to survive for 4.6 billion years mostly unscathed.

Headshot of Lionel Vacher
Vacher

“This is one of the most primitive meteorites in our collection,” Vacher said. “It was not heated significantly. It contains porous regions and tiny grains that formed around other stars. It is a reliable witness to the solar system’s formation.”

Acfer 094 is also the only meteorite that contains cosmic symplectite, an intergrowth of iron-oxide and iron-sulfide with extremely heavy oxygen isotopes — a significant finding.

The sun contains about 6% more of the lightest oxygen isotope compared with the rest of the solar system. That can be explained by ultraviolet light shining on the solar system’s building blocks, selectively breaking apart carbon monoxide gas into its constituent atoms. That process also creates a reservoir of much heavier oxygen isotopes. Until cosmic symplectite, however, no one had found this heavy isotope signature in samples of solar system materials.

Cosmic symplectite in the meteorite Acfer 094. (Image: Ryan Ogliore , Laboratory for Space Sciences)

With only three isotopes, however, simply finding the heavy oxygen isotopes wasn’t enough to answer the question of the origin of the light. Different ultraviolet spectra could have created the same result.

“That’s when Ryan came up with the idea of sulfur isotopes,” Vacher said.

Sulfur’s four isotopes would leave their marks in different ratios depending on the spectrum of ultraviolet light that irradiated hydrogen sulfide gas in the proto-solar system. A massive star and a young sun-like star have different ultraviolet spectra.

Cosmic symplectite formed when ices on the asteroid melted and reacted with small pieces of iron-nickel metal. In addition to oxygen, cosmic symplectite contains sulfur in iron sulfide. If its oxygen witnessed this ancient astrophysical process — which led to the heavy oxygen isotopes — perhaps its sulfur did, too.

“We developed a model,” Ogliore said. “If I had a massive star, what isotope anomalies would be created? What about for a young, sun-like star? The precision of the model depends on the experimental data. Fortunately, other scientists have done great experiments on what happens to isotope ratios when hydrogen sulfide is irradiated by ultraviolet light.”

Sulfur and oxygen isotope measurements of cosmic symplectite in Acfer 094 proved another challenge. The grains, tens of micrometers in size and a mixture of minerals, required new techniques on two different in-situ secondary-ion mass spectrometers: the NanoSIMS in the physics department (with assistance from Nan Liu, research assistant professor in physics) and the 7f-GEO in the Department of Earth and Planetary Sciences, also in Arts & Sciences.

Putting the puzzle together

It helped to have friends in earth and planetary sciences, particularly David Fike, professor of earth and planetary sciences and director of Environmental Studies in Arts & Sciences as well as director of the International Center for Energy, Environment and Sustainability, and Clive Jones, research scientist in earth and planetary sciences.

181-825 is one of the bright proplyds — protoplanetary disks — that lies relatively close to the Orion nebula’s brightest star, Theta 1 Orionis C. Resembling a tiny jellyfish, this proplyd is surrounded by a shock wave that is caused by stellar wind from the massive Theta 1 Orionis C interacting with gas in the nebula. (Image:  Credit: NASA/ESA and L. Ricci [ESO].)

“They are experts in high-precision in-situ sulfur isotope measurements for biogeochemistry,” Ogliore said. “Without this collaboration, we would not have achieved the precision we needed to differentiate between the young sun and massive star scenarios.”

The sulfur isotope measurements of cosmic symplectite were consistent with ultraviolet irradiation from a massive star, but did not fit the UV spectrum from the young sun. The results give a unique perspective on the astrophysical environment of the sun’s birth 4.6 billion years ago. Neighboring massive stars were likely close enough that their light affected the solar system’s formation. Such a nearby massive star in the night sky would appear brighter than the full moon.

Today, we can look to the skies and see a similar origin story play out elsewhere in the galaxy.

“We see nascent planetary systems, called proplyds, in the Orion nebula that are being photoevaporated by ultraviolet light from nearby massive O and B stars,” Vacher said.

“If the proplyds are too close to these stars, they can be torn apart, and planets never form. We now know our own solar system at its birth was close enough to be affected by the light of these stars,” he said. “But thankfully, not too close.”

This work was supported by the McDonnell Center for Space Sciences at Washington University in St. Louis and NASA grant NNX14AF22G.

Featured image: The Carina nebula, where newborn stars are irradiated by intense ultraviolet light from nearby massive stars – possibly similar to the environment which birthed our solar system – is pictured over a fragment of Acfer 094. (Carina nebula image: NASA; ESA; N. Smith ,University of California, Berkeley; and The Hubble Heritage Team (STScI/AURA). Acfer 094 image: Ryan Ogliore).


Reference: Lionel G. Vacher, Ryan C. Ogliore, Clive Jones, Nan Liu, David A. Fike, Cosmic symplectite recorded irradiation by nearby massive stars in the solar system’s parent molecular cloud, Geochimica et Cosmochimica Acta, 2021, , ISSN 0016-7037, https://doi.org/10.1016/j.gca.2021.06.026. (https://www.sciencedirect.com/science/article/pii/S0016703721003756)


Provided by WUSTL

Researchers Trace Dust Grain’s Journey Through Newborn Solar System (Cosmology)

Combining atomic-scale sample analysis and models simulating likely conditions in the nascent solar system, a new study reveals clues about the origin of crystals that formed more than 4.5 billion years ago.

A research team led by the University of Arizona has reconstructed in unprecedented detail the history of a dust grain that formed during the birth of the solar system more than 4.5 billion years ago. The findings provide insights into the fundamental processes underlying the formation of planetary systems, many of which are still shrouded in mystery.

For the study, the team developed a new type of framework, which combines quantum mechanics and thermodynamics, to simulate the conditions to which the grain was exposed during its formation, when the solar system was a swirling disk of gas and dust known as a protoplanetary disk or solar nebula. Comparing the predictions from the model to an extremely detailed analysis of the sample’s chemical makeup and crystal structure, along with a model of how matter was transported in the solar nebula, revealed clues about the grain’s journey and the environmental conditions that shaped it along the way.

The grain analyzed in the study is one of several inclusions, known as calcium-aluminum rich inclusions, or CAIs, discovered in a sample from the Allende meteorite, which fell over the Mexican state of Chihuahua in 1969. CAIs are of special interest because they are thought to be among the first solids that formed in the solar system more than 4.5 billion years ago.

Allende Meteorite
This piece of the Allende meteorite shows the typical crust of material that melted during entry into Earth’s atmosphere. The grain studied in this study was taken from a similar piece, and from deep within the specimen, where little, if any, alteration would occur during the meteorite fall.H. Raab/Wikimedia Commons

Similar to how stamps in a passport tell a story about a traveler’s journey and stops along the way, the samples’ micro- and atomic-scale structures unlock a record of their formation histories, which were controlled by the collective environments to which they were exposed.

“As far as we know, our paper is the first to tell an origin story that offers clues about the likely processes that happened at the scale of astronomical distances with what we see in our sample at the scale of atomic distances,” said Tom Zega, a professor in the University of Arizona’s Lunar and Planetary Laboratory and the first author of the paper, published in The Planetary Science Journal.

Zega and his team analyzed the composition of the inclusions embedded in the meteorite using cutting-edge atomic-resolution scanning transmission electron microscopes – one at UArizona’s Kuiper Materials Imaging and Characterization Facility, and its sister microscope located at the Hitachi factory in Hitachinaka, Japan.

The inclusions were found to consist mainly of types of minerals known as spinel and perovskite, which also occur in rocks on Earth and are being studied as candidate materials for applications such as microelectronics and photovoltaics.

Similar kinds of solids occur in other types of meteorites known as carbonaceous chondrites, which are particularly interesting to planetary scientists as they are known to be leftovers from the formation of the solar system and contain organic molecules, including those that may have provided the raw materials for life.

A slice through an Allende meteorite
A slice through an Allende meteorite reveals various spherical particles, known as chondrules. The irregularly shaped “island” left of the center is a calcium-aluminum rich inclusion, or CAI. The grain in this study was isolated from such a CAI.Shiny Things/Wikimedia Commons

Precisely analyzing the spatial arrangement of atoms allowed the team to study the makeup of the underlying crystal structures in great detail. To the team’s surprise, some of the results were at odds with current theories on the physical processes thought to be active inside protoplanetary disks, prompting them to dig deeper.

“Our challenge is that we don’t know what chemical pathways led to the origins of these inclusions,” Zega said. “Nature is our lab beaker, and that experiment took place billions of years before we existed, in a completely alien environment.”

Zega said the team set out to “reverse-engineer” the makeup of the extraterrestrial samples by designing new models that simulated complex chemical processes, which the samples would be subjected to inside a protoplanetary disk.

“Such models require an intimate convergence of expertise spanning the fields of planetary science, materials science, mineral science and microscopy, which was what we set out to do,” added Krishna Muralidharan, a study co-author and an associate professor in the UArizona’s Department of Materials Science and Engineering.

Based on the data the authors were able to tease from their samples, they concluded that the particle formed in a region of the protoplanetary disk not far from where Earth is now, then made a journey closer to the sun, where it was progressively hotter, only to later reverse course and wash up in cooler parts farther from the young sun. Eventually, it was incorporated into an asteroid, which later broke apart into pieces. Some of those pieces were captured by Earth’s gravity and fell as meteorites.

The samples for this study were taken from the inside of a meteorite and are considered primitive – in other words, unaffected by environmental influences. Such primitive material is believed to not have undergone any significant changes since it first formed more than 4.5 billion years ago, which is rare. Whether similar objects occur in asteroid Bennu, samples of which will be returned to Earth by the UArizona-led OSIRIS-REx mission in 2023, remains to be seen. Until then, scientists rely on samples that fall to Earth via meteorites.

Illustration of the dynamic history that the modeled particle could have experienced during the formation of the solar system
Illustration of the dynamic history that the modeled particle could have experienced during the formation of the solar system. Analyzing the particle’s micro- and atomic-scale structures and combining them with new models that simulated complex chemical processes in the disk revealed its possible journey over the course of many orbits around the sun (callout box and diagram on the right). Originating not far from where Earth would form, the grain was transported into the inner, hotter regions, and eventually washed up in cooler regions.Heather Roper/Zega et al.

“This material is our only record of what happened 4.567 billion years ago in the solar nebula,” said Venkat Manga, a co-author of the paper and an assistant research professor in the UArizona Department of Materials Science and Engineering. “Being able to look at the microstructure of our sample at different scales, down to the length of individual atoms, is like opening a book.”

The authors said that studies like this one could bring planetary scientists a step closer to “a grand model of planet formation” – a detailed understanding of the material moving around the disk, what it is composed of, and how it gives rise to the sun and the planets.

Powerful radio telescopes like the Atacama Large Millimeter/submillimeter Array, or ALMA, in Chile now allow astronomers to see stellar systems as they evolve, Zega said.

“Perhaps at some point we can peer into evolving disks, and then we can really compare our data between disciplines and begin answering some of those really big questions,” Zega said. “Are these dust particles forming where we think they did in our own solar system? Are they common to all stellar systems? Should we expect the pattern we see in our solar system – rocky planets close to the central star and gas giants farther out – in all systems?

“It’s a really interesting time to be a scientist when these fields are evolving so rapidly,” he added. “And it’s awesome to be at an institution where researchers can form transdisciplinary collaborations among leading astronomy, planetary and materials science departments at the same university.”

The study was co-authored by Fred Ciesla at the University of Chicago and Keitaro Watanabe and Hiromi Inada, both with the Nano-Technology Solution Business Group at Hitachi High-Technologies Corp. in Japan.

Funding was provided through NASA’s Emerging Worlds Program; NASA’s Origins Program; and NASA’s Nexus for Exoplanet System Science (NExSS) research coordination network, which is sponsored by NASA’s Science Mission Directorate. NASA and the National Science Foundation provided the funding for the instrumentation in LPL’s Kuiper Materials Imaging and Characterization Facility.

Featured image: Artist’s illustration of the early solar system, at a time when no planets had formed yet. A swirling cloud of gas and dust surrounded the young sun. The cutaway through this so-called protoplanetary disk shows its three-dimensional structure. © Heather Roper


Provided by University of Arizona

Meteorite Amino Acids Derived from Substrates More Widely Available in the Early Solar System (Planetary Science)

Scientists have recreated the reaction by which carbon isotopes made their way into different organic compounds, challenging the notion that organic compounds, such as amino acids, were formed by isotopically enriched substrates. Their discovery suggests that the building blocks of life in meteorites were derived from widely available substrates in the early solar system.

Their findings were published online in Science Advances on April 28, 2021.

Carbonaceous meteorites contain the building blocks of life, including amino acids, sugars, and nucleobases. These meteorites are potential providers of these molecules to the prebiotic Earth.

The small organic molecules found in meteorites are generally enriched in a heavy carbon isotope (13C). However, the most abundant organic matter in meteorites is depleted in 13C. Such a difference has long since puzzled scientists. It has been thought the small molecules came from 13C enriched substances found in the extremely cold outer solar system and/or the solar nebula.

Murchison Meteorite © Yoshihiro Furukawa

However, a team of researchers from Tohoku University and Hokkaido University has presented a new hypothesis. They argue that the formose-type reactions, the formation of sugar from formaldehyde, create sizeable differences in the 13C concentration between small and large organic molecules.

Recreating the formose-type reaction in the lab, the researchers found that the carbon isotope components of meteorite organics are created by the formose-type reaction even in a hot aqueous solution.

Their findings suggest that the organic compounds were formed without the use of isotopically enriched substrates from the outer solar system; rather, their formation may have taken place using substrates commonly present in the early solar system.

“The discrepancy in carbon isotopic composition between the small organic compounds and large insoluble organic matter is one of the most mysterious characteristics of meteorite organic compounds,” said Tohoku University’s Yoshihiro Furukawa, lead-author of the study. “However, the behavior of 13C in this reaction solves the puzzle completely.”

“Even though the compounds were synthesized 4.6 billion years ago, the isotope compositions tell us the process of synthetic reaction,” added co-author Yoshito Chikaraishi, from Hokkaido University.

Looking ahead, the research group is planning to investigate the impact of the formose-type reaction in nitrogen and carbon isotope characteristics in a number of meteorite organics and carbonates.

Featured image: Asteroid Ryugu © JAXA


Reference: Y. Furukawa, Y. Iwasa et al., “Synthesis of 13C-enriched amino acids with 13C-depleted insoluble organic matter in a formose-type reaction in the early solar system”, Science Advances  28 Apr 2021: Vol. 7, no. 18, eabd3575 DOI: 10.1126/sciadv.abd3575


Provided by Tohoku University

Does Kuiper Belt In Our Solar System Still Produce Gas? (Planetary Science)

Summary:

⦿ Gas is now discovered commonly in exoplanetary systems with planetesimal belts.

⦿ Now, Karl and colleagues for the first time verified whether Kuiper Belt in our Solar System still produce gas.

⦿ They found that it is still producing carbon monoxide gas at the rate of 2 × 10¯8 M/Myr.

⦿ According to them, current instruments unable to validate it through observations. But future in-situ instruments having larger effective areas and pixel sizes could be able to detect it.


The past decade was very prolific in terms of detecting gas (mostly CO, C and O) around main sequence stars, therefore changing the paradigm of evolved planetary systems that were thought to be devoid of gas after 10 Myr. Indeed, most bright exoplanetesimal belts show the presence of gas, as demonstrated recently with ALMA, and it could be that all these belts have gas at some level (even if undetectable with current instruments). These belts, similar to our Kuiper belt, are made of large bodies colliding with each other and creating dust that can then be observed around extrasolar stars through its emission in the infrared above that of the star, which can be resolved at high resolution (showing, e.g., gaps and asymmetries that may be related to the presence of planets).

Now, Kral and colleagues by using sublimation model verified whether gas is also expected in the Kuiper belt (KB) in our Solar System. They predicted that gas is still produced in the KB right now at a rate of 2 × 10¯8 M/Myr for carbon monoxide (CO). Once released, the gas is quickly pushed out by the Solar wind. Therefore, they predicted a gas wind in our Solar System starting at the KB location and extending far beyond with a current total CO mass of ∼ 2 × 10¯12 M (i.e. 20 times the CO quantity that was lost by the Hale-Bopp comet during its sole 1997 passage) and CO density in the belt of 3 × 10¯7 cm¯3. They also predicted the existence of a slightly more massive atomic gas wind made of carbon and oxygen (neutral and ionized) with a mass of ∼ 10¯11 M.

Figure 1: CO gas production rate in the Kuiper belt M˙_CO as a function of time (t = 0 is when the gas release starts, i.e., probably after a few Myr to 10 Myr and the end of the lines on the right is today) predicted by their sublimation model. The solid line is for the Kuiper belt assuming it starts with a low mass similar to the current KB mass and the dashed line is for a more massive belt similar to the archetype β Pic belt. © Karl et al.

The question is, if KB really produce gas, why we haven’t been able to validate it through observations? Well, according to Kral and colleagues, we haven’t detected gas from KB yet, because the release is more diffuse as the emission comes from many Kuiper Belt Objects (KBOs) and it would be difficult to observe because of the lack of spatial contrast compared to extrasolar systems where most emission comes from a few beams. They predicted that Planck and ALMA (in a total power array mode) do not have enough sensitivity to detect the CO rotational lines of the diffuse wind.

The gas accumulated in the midplane of the KB along the line of sight to a background star would create some absorption in the UV on the star spectrum that could be identified as gas in our Solar System. However, they found that only future instruments may be able to detect this faint absorption. Furthermore, they suggested that the most promising technique would be to use in-situ missions similar to New Horizons to detect emission of resonance line scattering of carbon and/or oxygen excited by the Sun’s UV light. However, the effective area of the future potential instrument and its pixel size would need to be much larger to reach the low column density level predicted for atoms in the KB.

The presence of current gas predicted by their model in our Solar System would not impact the dynamics of bodies (dust or planetesimals) evolving around the KB. However, they note that in the past, when the Kuiper belt was much younger and heavier, the release of CO would have been orders of magnitude larger and the gas dynamics would have also been much different (e.g., in the fluid/hydrodynamic regime), potentially leading to some interesting effects, such as delivering some CO mass from the KB to planetary atmospheres as proposed recently for extrasolar systems.


Reference: Quentin Kral, J. E. Pringle, Aurélie Guilbert-Lepoutre, Luca Matrà, Julianne I. Moses, Emmanuel Lellouch, Mark C. Wyatt, Nicolas Biver, Dominique Bockelée-Morvan, Amy Bonsor, Franck Le Petit, “A molecular wind blows out of the Kuiper belt”, ArXiv, pp. 1-40, 2021. https://arxiv.org/abs/2104.01035


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Subaru Telescope Updates Records of Celestial Bodies Found Farthest in the Solar System (Planetary Science)

With the Hyper Suprime-Cam (HSC), an ultra-wide-field primary focus camera mounted on the Subaru Telescope, a new location is available at a very distant location of about 132 times the distance between the Sun and the Earth (132 astronomical units). A celestial body (nickname: Farfarout) was discovered. It is the celestial body with the longest distance at the time of discovery among the currently known celestial bodies in the solar system.

Farfarout was discovered by researchers at the Carnegie Institute in the United States, the University of Hawaii, and the University of Northern Arizona in 2018 with the Subaru Telescope, and after several years of follow-up observations with the Gemini Northern Telescope and Magellan Telescope, its orbit has been improved. I was asked. Currently, Farfarout is about 132 astronomical units from the Sun, about four times the distance between the Sun and Pluto. The farthest celestial body found in the solar system, 2018 VG 18 (nickname: Farout), was about 120 astronomical units at the time of its discovery. This is also an astronomical object discovered by the research team using the Subaru Telescope ( article released on December 17, 2018 ).

Dr. David Tholen (University of Hawaii) of the research team said, “It will take about 1000 years for Far Farout to orbit the Sun. It requires years of observation. “

Farfarout’s orbit is elongated, with the aphelion (farthest from the Sun) about 175 AUs and the perihelion (closest to the Sun) about 27 AUs inside Neptune’s orbit. The researchers speculate that the gravitational interaction with Neptune in the past may have caused the Farfarout’s orbit to become elongated. Dr. Chad Trujillo (Northern Arizona University) said, “Far Farout may have been pushed out of the solar system because it was too close to Neptune. Far Farout’s orbit is also interesting for understanding Neptune’s formation and evolution. Because the orbits intersect, there will continue to be opportunities for Far Farout and Neptune to have great gravitational interactions. “

Due to the strong influence of Neptune’s gravity, it is not possible to investigate the existence of unknown planets in the solar system from Farfarout’s orbit. The existence of the unknown planet “Planet Nine (Ninth Planet)”, which may be farther than Neptune, comes from the orbits of celestial bodies further outside Neptune’s orbit, such as “2012 VP 113 ” and “Sedna”. It has been suggested. The research team is exploring such trans-Neptunian objects using the Subaru Telescope (Reference: Article released on October 3, 2018 ).

Figure 2:  Image illustration of  Far Far Out (2018 AG 37 ) and a graph showing the distance of celestial bodies in the solar system.  Green, yellow, orange, and red represent planets, dwarf planets, dwarf planet candidates, and far-far-outs, respectively.  (Credit: NOIR Lab / NSF / AURA / J. da Silva)

The research team estimates the diameter of Farfarout to be about 400 kilometers, based on the brightness and distance of Farfarout and the assumption that it is an ice-rich object. If it is a dwarf planet, it is a celestial body near the lower limit.

Dr. Scott Sheppard (Carnegie Institution for Science) said, “The discovery of Farfarout shows that humans’ ability to capture the whole picture of the outer edge of the solar system and explore further distances has improved. The recent development of attached giant digital cameras has made it possible for the first time to efficiently find distant objects such as Farfarout, even if they are quasi-planetary in size. It is observed as a very dark celestial body because it is far away. Far-far-out is probably just the tip of an ice mine among the celestial bodies at the end of the solar system. ” He talks about his expectations.

This new object was given the provisional designation “2018 AG 37 ” on February 10, 2021 by the International Astronomical Union Minor Planet Center ( Minor Planet Electric Circular 2021-C187 ). The official name will be given after more accurate orbits have been determined in observations over the next few years.

Featured image: Discovered images of Far Far Out (2018 AG 37 ) observed by the Subaru Telescope on January 15 and 16, 2018 . You can see the movement of the new celestial body from the images taken after a while. (Credit: Scott S. Sheppard)

Image of The Week: Through the Clouds (Astronomy)

Nestled amongst the vast clouds of star-forming regions like this one lie potential clues about the formation of our own Solar System. 

This week’s NASA/ESA Hubble Space Telescope Picture of the Week features AFGL 5180, a beautiful stellar nursery located in the constellation of Gemini (The Twins). 

At the centre of the image, a massive star is forming and blasting cavities through the clouds with a pair of powerful jets, extending to the top right and bottom left of the image. Light from this star is mostly escaping and reaching us by illuminating these cavities, like a lighthouse piercing through the storm clouds.

Stars are born in dusty environments and although this dust makes for spectacular images, it can prevent astronomers from seeing stars embedded in it. Hubble’s Wide Field Camera 3 (WFC3) instrument is designed to capture detailed images in both visible and infrared light, meaning that the young stars hidden in vast star-forming regions like AFGL 5180 can be seen much more clearly. 

Credit: ESA/Hubble & NASA, J. C. Tan (Chalmers University & University of Virginia), R. Fedriani (Chalmers University) Acknowledgement: Judy Schmidt

About the Object

Name: AFGL 5180, Constellation: Gemini, Category: Stars


Provided by ESA/Hubble

Extinct Atom Reveals The Long-kept Secrets of The Solar System (Astronomy)

Using the extinct niobium-​92 atom, ETH researchers have been able to date events in the early solar system with greater precision than before. The study concludes that supernova explosions must have taken place in the birth environment of our sun.

If an atom of a chemical element has a surplus of protons or neutrons, it becomes unstable. It will shed these additional particles as gamma radiation until it becomes stable again. One such unstable isotope is niobium-​92 (92Nb), which experts also refer to as a radionuclide. Its half-​life of 37 million years is relatively brief, so it went extinct shortly after the formation of the solar system. Today, only its stable daughter isotope, zirconium-​92 (92Zr), bears testimony to the existence of 92Nb.

Yet scientists have continued to make use of the extinct radionuclide in the form of the 92Nb-92Zr chronometer, with which they can date events that took place in the early solar system some 4.57 billion years ago.

Use of the 92Nb-92Zr chronometer has hitherto been limited by a lack of precise information regarding the amount of 92Nb that was present at the birth of the solar system. This compromises its use for dating and determining the production of these radionuclides in stellar environments.

Meteorites hold the key to the distant past

Now a research team from ETH Zurich and the Tokyo Institute of Technology (Tokyo Tech) has greatly improved this chronometer. The researchers achieved this improvement by means of a clever trick: they recovered rare zircon and rutile minerals from meteorites that were fragments of the protoplanet Vesta. These minerals are considered to be the most suitable for determing 92Nb, because they give precise evidence of how common 92Nb was at the time of the meteorite’s formation. Then, with the uranium-​lead dating technique (uranium atoms that decay into lead), the team calculated how abundant 92Nb was at the time the solar system’s formation. By combining the two methods, the researchers succeeded in considerably improving the precision of the 92Nb-92Zr chronometer.

“This improved chronometer is thus a powerful tool for providing precise ages for the formation and development of asteroids and planets – events that happened in the first tens of millions of years after the formation of the solar system,” says Maria Schönbächler, Professor at the Institute of Geochemistry and Petrology at ETH Zurich, who led the study.

Supernovas released niobium-​92

Now that the researchers know more precisely how abundant 92Nb was at the very beginnings of our solar system, they can determine more accurately where these atoms were formed and where the material that makes up our sun and the planets originated.

The research team’s new model suggests that the inner solar system, with the terrestrial planets Earth and Mars, is largely influenced by material ejected by Type Ia supernovae in our Milky Way galaxy. In such stellar explosions, two orbiting stars interact with each other before exploding and releasing stellar material. In contrast, the outer solar system was fed primarily by a core-collapse supernova – probably in the stellar nursery where our sun was born –, in which a massive star collapsed in on itself and exploded violently.

Featured image: The unstable atom 92Nb, which has long since disappeared, provides information about the beginnings of our solar system. (Illustration: Makiko K. Haba)


Reference

Haba MK, Lai Y-J, Wotzlaw J-F, Yamaguchi A, Lugaro M, Schönbächler M. Precise initial abundance of Niobium-92 in the Solar System and implications for p-process nucleosynthesis. PNAS February 23, 2021 118 (8) e2017750118. DOI: 10.1073/pnas.2017750118


Provided by University of Zurich

‘Farfarout!’ Solar System’s Most Distant Planetoid Confirmed (Planetary Science)

A team, including an astronomer from the University of Hawaiʻi Institute for Astronomy (IfA), have confirmed a planetoid that is almost four times farther from the Sun than Pluto, making it the most distant object ever observed in our solar system. The planetoid, nicknamed “Farfarout,” was first detected in 2018, and the team has now collected enough observations to pin down the orbit. The Minor Planet Center has now given it the official designation of 2018 AG37.

Farfarout’s name distinguished it from the previous record holder “Farout,” found by the same team of astronomers in 2018. The team includes UH Mānoa’s David Tholen, Scott S. Sheppard of the Carnegie Institution for Science, and Chad Trujillo of Northern Arizona University, who have an ongoing survey to map the outer solar system beyond Pluto.

Journey around the Sun

Farfarout’s current distance from the Sun is 132 astronomical units (au); 1 au is the distance between the Earth and Sun. For comparison, Pluto is only 34 au from the Sun. The newly discovered object has a very elongated orbit that takes it out to 175 au at its most distant, and inside the orbit of Neptune, to around 27 au, when it is closest to the Sun.

Farfarout’s journey around the Sun takes about a thousand years, crossing the giant planet Neptune’s orbit every time. This means Farfarout has probably experienced strong gravitational interactions with Neptune over the age of the solar system, and is the reason why it has such a large and elongated orbit.

“A single orbit of Farfarout around the Sun takes a millennium,” said Tholen. “Because of this long orbital period, it moves very slowly across the sky, requiring several years of observations to precisely determine its trajectory.”

Discovered on Maunakea

Farfarout will be given an official name after its orbit is better determined over the next few years. It was discovered at the Subaru 8-meter telescope located atop Maunakea in Hawaiʻi, and recovered using the Gemini North and Magellan telescopes in the past few years to determine its orbit based on its slow motion across the sky.

Farfarout is very faint, and based on its brightness and distance from the Sun, the team estimates its size to be about 400 km across, putting it on the low end of being a dwarf planet, assuming it is an ice-rich object.

“The discovery of Farfarout shows our increasing ability to map the outer solar system and observe farther and farther towards the fringes of our solar system,” said Sheppard. “Only with the advancements in the last few years of large digital cameras on very large telescopes has it been possible to efficiently discover very distant objects like Farfarout. Even though some of these distant objects are quite large, being dwarf planet in size, they are very faint because of their extreme distances from the Sun. Farfarout is just the tip of the iceberg of solar system objects in the very distant solar system.”

Interacting with Neptune

Because Neptune strongly interacts with Farfarout, its orbit and movement cannot be used to determine if there is another unknown massive planet in the very distant solar system, since these interactions dominate Farfarout’s orbital dynamics. Only those objects whose orbits stay in the very distant solar system, well beyond Neptune’s gravitational influence, can be used to probe for signs of an unknown massive planet. These include Sedna and 2012 VP113, which, although they are currently closer to the Sun than Farfarout (at around 80 au), they never approach Neptune and thus would be most influenced by the possible Planet X instead.

“Farfarout’s orbital dynamics can help us understand how Neptune formed and evolved, as Farfarout was likely thrown into the outer solar system by getting too close to Neptune in the distant past,” said Trujillo. “Farfarout will likely interact with Neptune again since their orbits continue to intersect.”

This research is an example of UH Mānoa’s goal of Excellence in Research: Advancing the Research and Creative Work Enterprise (PDF), one of four goals identified in the 2015–25 Strategic Plan (PDF), updated in December 2020.

Featured image: (Photo credit: Roberto Molar Candanosa, Scott S. Sheppard from Carnegie Institution for Science, and Brooks Bays from University of Hawaiʻi.)


This news is confirmed by us from University of Hawaii


Provided by University of Hawaii at Manoa

Solar System Formation in Two Steps (Astronomy)

An international team of researchers from the University of Oxford, LMU Munich, ETH Zurich, BGI Bayreuth, and the University of Zurich discovered that a two-step formation process of the early Solar System can explain the chronology and split in volatile and isotope content of the inner and outer Solar System.

The inner terrestrial protoplanets accrete early, inherit a substantial amount of radioactive 26Al, and hence melt, form iron cores, and degas their primordial volatile abundances rapidly. The outer Solar System planets start to accrete later and further out with less radiogenic heating, and hence retain the majority of their initially accreted volatiles. © Mark A Garlick/markgarlick.com

Their findings will be published in Science (Friday 22 January 2021; under embargo until 2pm US Eastern Time Thursday 21 January 2021).

The paper presents a new theoretical framework for the formation and structure of the Solar System that can explain several key features of the terrestrial planets (like Earth, Venus, and Mars), outer Solar System (like Jupiter), and composition of asteroids and meteorite families. The team’s work draws on and connects recent advances in astronomy (namely observations of other solar systems during their formation) and meteoritics – laboratory experiments and analyses on the isotope, iron, and water content in meteorites.

The suggested combination of astrophysical and geophysical phenomena during the earliest formation phase of the Sun and the Solar System itself can explain why the inner Solar System planets are small and dry with little water by mass, while the outer Solar System planets are larger and wet with lots of water. It explains the meteorite record by forming planets in two distinct steps. The inner terrestrial protoplanets accreted early and were internally heated by strong radioactive decay; this dried them out and split the inner, dry from the outer, wet planetary population. This has several implications for the distribution and necessary formation conditions of planets like Earth in extrasolar planetary systems.

The numerical experiments performed by the interdisciplinary team showed that the relative chronologies of early onset and protracted finish of accretion in the inner Solar System, and a later onset and more rapid accretion of the outer Solar System planets can be explained by two distinct formation epochs of planetesimals, the building blocks of the planets. Recent observations of planet-forming disks showed that disk midplanes, where planets form, may have relatively low levels of turbulence. Under such conditions the interactions between the dust grains embedded in the disk gas and water around the orbital location where it transitions from gas to ice phase (the snow line) can trigger an early formation burst of planetesimals in the inner Solar System and another one later and further out.

The two distinct formation episodes of the planetesimal populations, which further accrete material from the surrounding disk and via mutual collisions, result in different geophysical modes of internal evolution for the forming protoplanets. Dr Tim Lichtenberg from the Department of Atmospheric, Oceanic and Planetary Physics at the University of Oxford and lead-author of the study notes: ‘The different formation time intervals of these planetesimal populations mean that their internal heat engine from radioactive decay differed substantially. Inner Solar System planetesimals became very hot, developed internal magma oceans, quickly formed iron cores, and degassed their initial volatile content, which eventually resulted in dry planet compositions. In comparison, outer Solar System planetesimals formed later and therefore experienced substantially less internal heating and therefore limited iron core formation, and volatile release.

‘The early-formed and dry inner Solar System and the later-formed and wet outer Solar System were therefore set on two different evolutionary paths very early on in their history. This opens new avenues to understand the origins of the earliest atmospheres of Earth-like planets and the place of the Solar System within the context of the exoplanetary census across the galaxy.’

This research was supported by funding from the Simons Collaboration on the Origins of Life, the Swiss National Science Foundation, and the European Research Council.

The full study, ‘Bifurcation of planetary building blocks during Solar System formation’, will be published on 22 January 2021 in Science, 371, 6527. DOI: 10.1126/science.abb3091

Provided by University of Oxford