Thursday, April 30, 2020

Newly Discovered Exoplanet Dethrones Former King of Kepler-88 Planetary System

An artist’s illustration of the Kepler-88 planetary system.
Credit: W. M. Keck Observatory/Adam Makarenko


Kepler-88 d has three times the mass of Kepler-88 c, making the newly found planet the most massive one known in this system.  Animation Credit: W. M. Keck Observatory/Adam Makarenko


Hawaii Astronomer Discovers Massive Extrasolar Planet with Maunakea Telescope

Maunakea, Hawaii – Our solar system has a king. The planet Jupiter, named for the most powerful god in the Greek pantheon, has bossed around the other planets through its gravitational influence. With twice the mass of Saturn, and 300 times that of Earth, Jupiter’s slightest movement is felt by all the other planets. Jupiter is thought to be responsible for the small size of Mars, the presence of the asteroid belt, and a cascade of comets that delivered water to young Earth.

Do other planetary systems have gravitational gods like Jupiter?

A team of astronomers led by the University of Hawaiʻi Institute for Astronomy (UH IfA) has discovered a planet three times the mass of Jupiter in a distant planetary system.

The discovery is based on six years of data taken at W. M. Keck Observatory on Maunakea in Hawaiʻi. Using the High-Resolution Echelle Spectrometer (HIRES) instrument on the 10-meter Keck I telescope, the team confirmed that the planet, named Kepler-88 d, orbits its star every four years, and its orbit is not circular, but elliptical. At three times the mass of Jupiter, Kepler-88 d is the most massive planet in this system.

The system, Kepler-88, was already famous among astronomers for two planets that orbit much closer to the star, Kepler-88 b and c (planets are typically named alphabetically in the order of their discovery).

Those two planets have a bizarre and striking dynamic called mean motion resonance. The sub-Neptune sized planet b orbits the star in just 11 days, which is almost exactly half the 22-day orbital period of planet c, a Jupiter-mass planet. The clockwork-like nature of their orbits is energetically efficient, like a parent pushing a child on a swing. Every two laps planet b makes around the star, it gets pumped. The outer planet, Kepler-88 c, is twenty times more massive than planet b, and so its force results in dramatic changes in the orbital timing of the inner planet.

Astronomers observed these changes, called transit timing variations, with the NASA Kepler space telescope, which detected the precise times when Kepler-88 b crossed (or transited) between the star and the telescope. Although transit timing variations (TTVs for short) have been detected in a few dozen planetary systems, Kepler-88 b has some of the largest timing variations. With transits arriving up to half a day early or late, the system is known as “the King of TTVs.”

The newly discovered planet adds another dimension to astronomers’ understanding of the system.

“At three times the mass of Jupiter, Kepler-88 d has likely been even more influential in the history of the Kepler-88 system than the so-called King, Kepler-88 c, which is only one Jupiter mass,” says Dr. Lauren Weiss, Beatrice Watson Parrent Postdoctoral Fellow at UH IfA and lead author on the discovery team. “So maybe Kepler-88 d is the new supreme monarch of this planetary empire – the empress.”

Perhaps these extrasolar sovereign leaders have had as much influence as Jupiter did for our solar system. Such planets might have promoted the development of rocky planets and directed water-bearing comets toward them. Dr. Weiss and colleagues are searching for similar royal planets in other planetary systems with small planets.

Their paper announcing the discovery of Kepler-88 d is published in today’s issue of The Astronomical Journal and also available in preprint format on ArXiv.org.



About HIRES

The High-Resolution Echelle Spectrometer (HIRES) produces spectra of single objects at very high spectral resolution, yet covering a wide wavelength range. It does this by separating the light into many “stripes” of spectra stacked across a mosaic of three large CCD detectors. HIRES is famous for finding exoplanets. Astronomers also use HIRES to study important astrophysical phenomena like distant galaxies and quasars, and find cosmological clues about the structure of the early universe, just after the Big Bang.


About W. M. Keck Observatory

The W. M. Keck Observatory telescopes are among the most scientifically productive on Earth. The two, 10-meter optical/infrared telescopes on the summit of Maunakea on the Island of Hawaii feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectrometers, and world-leading laser guide star adaptive optics systems.

Some of the data presented herein were obtained at Keck Observatory, which is a private 501(c) 3 non-profit organization operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the Native Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.

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Subaru Telescope Captures First-ever Photographic Proof of Power-packed Jet Emerging from Colliding Galaxies

Figure 1: The Seyfert 1 galaxy, TXS 2116-077, (seen on the right) collides with another spiral-shaped galaxy of similar mass, creating a relativistic jet in the TXS's center. Both galaxies have active galactic nuclei (AGN). This image was obtained with the InfraRed Camera and Spectrograph (IRCS, in combination with its AO system AO 188, mounted at the Subaru Telescope on 2018 June 16. (Credit: Vaidehi Paliya).

A team of scientists using the Subaru Telescope has reported the first definitive detection of a relativistic jet emerging from two colliding galaxies - in essence, the first photographic proof that merging galaxies can produce jets of charged particles that travel at nearly the speed of light (Figure 1).

Furthermore, scientists had previously discovered that these jets could be found in elliptical-shaped galaxies, which can be formed in the merging of two spiral galaxies. Now, they have an image showing the formation of a jet from two younger, spiral-shaped galaxies.

"For the first time, we have found two spiral- or disk-shaped galaxies on path for a collision that have produced a nascent, baby jet that has just started its life at the center of one of the galaxies," said Dr. Vaidehi Paliya of the Deutsches Elektronen Synchrotron in Germany (and a former post-doctoral researcher at Clemson University), the lead author of the paper reporting this discovery.

The fact that the jet is so young enabled the researchers to clearly see its host. Scientists have already imaged galactic collisions many times. The research team is the first to capture two galaxies merging where there is a fully formed jet pointing at us - albeit, a very young one, and thus not yet bright enough to blind us.

Jets are the most powerful astrophysical phenomena in the universe. They can emit more energy into the universe in one second than our sun will produce in its entire lifetime. That energy is in the form of radiation, such as intense radio waves, X-rays, and gamma-rays.

Jets were thought to be born from older, elliptical-shaped galaxies with an active galactic nucleus (AGN), which is a super-massive black hole that resides at its center. As a point of reference, scientists believe all galaxies have centrally located super-massive black holes, but not all of them are AGNs. For example, our Milky Way's massive black hole is dormant.

Scientists theorize that the AGNs grow larger by gravitationally drawing in gas and dust through a process called accretion. But not all of this matter gets accreted into the black hole. Some of the particles become accelerated and are spewed outward in narrow beams in the form of jets.

The team's image captured the two galaxies, a Seyfert 1 galaxy known as TXS 2116-077 and another galaxy of similar mass, as they were colliding for the second time because of the amount of gas seen in the image.

Dr. Hyewon Suh of Subaru Telescope emphasizes the importance of the Subaru's observations, saying "With the deep and superb resolved imaging of the Subaru Telescope, we, for the first time, were able to capture this jet-emitting galaxy in the process of merging with a nearby companion at their close separation of just 40,000 light-years, indicating that they are in a final stage of merger and approaching coalescence."

"Scientists have carried out detailed numerical simulations and predicted that this event may ultimately lead to the formation of one giant elliptical galaxy," said Paliya. "Depending on the physical conditions, it may host a relativistic jet, but that's in the distant future."

The team captured the image using IRCS (in combination with AO 188) mounted at the Subaru Telescope. They performed subsequent observations with the Gran Telescopio Canarias and William Herschel Telescope on the island of La Palma off the coast of Spain, as well as with NASA's Chandra X-Ray Observatory space telescope.

This study was published in The Astrophysical Journal on April 1, 2020 (UT) (Paliya et al. 2020, "TXS 2116−077: A Gamma-Ray Emitting Relativistic Jet Hosted in a Galaxy Merger".


Relevant Links



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Wednesday, April 29, 2020

Spitzer Telescope Reveals the Precise Timing of a Black Hole Dance

This image shows two massive black holes in the OJ 287 galaxy. The smaller black hole orbits the larger one, which is also surrounded by a disk of gas. When the smaller black hole crashes through the disk, it produces a flare brighter than 1 trillion stars. Credit: NASA/JPL-Caltech.  › Larger view

Black holes aren't stationary in space; in fact, they can be quite active in their movements. But because they are completely dark and can't be observed directly, they're not easy to study. Scientists have finally figured out the precise timing of a complicated dance between two enormous black holes, revealing hidden details about the physical characteristics of these mysterious cosmic objects.

The OJ 287 galaxy hosts one of the largest black holes ever found, with over 18 billion times the mass of our Sun. Orbiting this behemoth is another black hole with about 150 million times the Sun's mass. Twice every 12 years, the smaller black hole crashes through the enormous disk of gas surrounding its larger companion, creating a flash of light brighter than a trillion stars - brighter, even, than the entire Milky Way galaxy. The light takes 3.5 billion years to reach Earth.
The OJ 287 galaxy hosts one of the largest black holes ever found, with over 18 billion times the mass of our Sun. Orbiting this behemoth is another massive black hole. Twice every 12 years, the smaller black hole crashes through the enormous disk of gas surrounding its larger companion, creating a flash of light brighter than a trillion stars. 

But the smaller black hole's orbit is oblong, not circular, and it's irregular: It shifts position with each loop around the bigger black hole and is tilted relative to the disk of gas. When the smaller black hole crashes through the disk, it creates two expanding bubbles of hot gas that move away from the disk in opposite directions, and in less than 48 hours the system appears to quadruple in brightness.

Because of the irregular orbit, the black hole collides with the disk at different times during each 12-year orbit. Sometimes the flares appear as little as one year apart; other times, as much as 10 years apart. Attempts to model the orbit and predict when the flares would occur took decades, but in 2010, scientists created a model that could predict their occurrence to within about one to three weeks. They demonstrated that their model was correct by predicting the appearance of a flare in December 2015 to within three weeks.

Then, in 2018, a group of scientists led by Lankeswar Dey, a graduate student at the Tata Institute of Fundamental Research in Mumbai, India, published a paper with an even more detailed model they claimed would be able to predict the timing of future flares to within four hours. In a new study published in the Astrophysical Journal Letters, those scientists report that their accurate prediction of a flare that occurred on July 31, 2019, confirms the model is correct.

The observation of that flare almost didn't happen. Because OJ 287 was on the opposite side of the Sun from Earth, out of view of all telescopes on the ground and in Earth orbit, the black hole wouldn't come back into view of those telescopes until early September, long after the flare had faded. But the system was within view of NASA's Spitzer Space Telescope, which the agency retired in January 2020.

After 16 years of operations, the spacecraft's orbit had placed it 158 million miles (254 million kilometers) from Earth, or more than 600 times the distance between Earth and the Moon. From this vantage point, Spitzer could observe the system from July 31 (the same day the flare was expected to appear) to early September, when OJ 287 would become observable to telescopes on Earth.

"When I first checked the visibility of OJ 287, I was shocked to find that it became visible to Spitzer right on the day when the next flare was predicted to occur," said Seppo Laine, an associate staff scientist at Caltech/IPAC in Pasadena, California, who oversaw Spitzer's observations of the system. "It was extremely fortunate that we would be able to capture the peak of this flare with Spitzer, because no other human-made instruments were capable of achieving this feat at that specific point in time." 

Ripples in Space

Scientists regularly model the orbits of small objects in our solar system, like a comet looping around the Sun, taking into account the factors that will most significantly influence their motion. For that comet, the Sun's gravity is usually the dominant force, but the gravitational pull of nearby planets can change its path, too. 

Determining the motion of two enormous black holes is much more complex. Scientists must account for factors that might not noticeably impact smaller objects; chief among them are something called gravitational waves. Einstein's theory of general relativity describes gravity as the warping of space by an object's mass. When an object moves through space, the distortions turn into waves. Einstein predicted the existence of gravitational waves in 1916, but they weren't observed directly until 2015 by the Laser Interferometer Gravitational Wave Observatory (LIGO). 

The larger an object's mass, the larger and more energetic the gravitational waves it creates. In the OJ 287 system, scientists expect the gravitational waves to be so large that they can carry enough energy away from the system to measurably alter the smaller black hole's orbit - and therefore timing of the flares. 

While previous studies of OJ 287 have accounted for gravitational waves, the 2018 model is the most detailed yet. By incorporating information gathered from LIGO's detections of gravitational waves, it refines the window in which a flare is expected to occur to just 1 1/2 days.

To further refine the prediction of the flares to just four hours, the scientists folded in details about the larger black hole's physical characteristics. Specifically, the new model incorporates something called the "no-hair" theorem of black holes. 

Published in the 1960s by a group of physicists that included Stephen Hawking, the theorem makes a prediction about the nature of black hole "surfaces." While black holes don't have true surfaces, scientists know there is a boundary around them beyond which nothing - not even light - can escape. Some ideas posit that the outer edge, called the event horizon, could be bumpy or irregular, but the no-hair theorem posits that the "surface" has no such features, not even hair (the theorem's name was a joke). 

In other words, if one were to cut the black hole down the middle along its rotational axis, the surface would be symmetric. (The Earth's rotational axis is almost perfectly aligned with its North and South Poles. If you cut the planet in half along that axis and compared the two halves, you would find that our planet is mostly symmetric, though features like oceans and mountains create some small variations between the halves.)

Finding Symmetry 

In the 1970s, Caltech professor emeritus Kip Thorne described how this scenario - a satellite orbiting a massive black hole - could potentially reveal whether the black hole's surface was smooth or bumpy. By correctly anticipating the smaller black hole's orbit with such precision, the new model supports the no-hair theorem, meaning our basic understanding of these incredibly strange cosmic objects is correct. The OJ 287 system, in other words, supports the idea that black hole surfaces are symmetric along their rotational axes.

So how does the smoothness of the massive black hole's surface impact the timing of the smaller black hole's orbit? That orbit is determined mostly by the mass of the larger black hole. If it grew more massive or shed some of its heft, that would change the size of smaller black hole's orbit. But the distribution of mass matters as well. A massive bulge on one side of the larger black hole would distort the space around it differently than if the black hole were symmetric. That would then alter the smaller black hole's path as it orbits its companion and measurably change the timing of the black hole's collision with the disk on that particular orbit.

"It is important to black hole scientists that we prove or disprove the no-hair theorem. Without it, we cannot trust that black holes as envisaged by Hawking and others exist at all," said Mauri Valtonen, an astrophysicist at University of Turku in Finland and a coauthor on the paper.

Spitzer science data continues to be analyzed by the science community via the Spitzer data archive located at the Infrared Science Archive housed at IPAC at Caltech in Pasadena. JPL managed Spitzer mission operations for NASA's Science Mission Directorate in Washington. Science operations were conducted at the Spitzer Science Center at IPAC at Caltech. Spacecraft operations were based at Lockheed Martin Space in Littleton, Colorado. Caltech manages JPL for NASA.


For more information about Spitzer, visit:  https://www.nasa.gov/spitzer -  http://www.spitzer.caltech.edu/


News Media Contact

Calla Cofield
Jet Propulsion Laboratory, Pasadena, Calif.
626-808-2469
calla.e.cofield@jpl.nasa.gov


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Tuesday, April 28, 2020

Hubble Captures Breakup of Comet ATLAS

Hubble’s New Observations of Comet C/2019 Y4 (ATLAS)

Hubble’s Observation of Comet C/2019 Y4 (ATLAS) on 20 April

Hubble’s Observation of Comet C/2019 Y4 (ATLAS) on 23 April

Videos

Animation of Comet ATLAS’ Orbit
Animation of Comet ATLAS’ Orbit

Animation of Hubble’s Observations of Comet C/2019 Y4 (ATLAS)
Animation of Hubble’s Observations of Comet C/2019 Y4 (ATLAS)


The NASA/ESA Hubble Space Telescope has provided astronomers with the sharpest view yet of the breakup of Comet C/2019 Y4 (ATLAS). The telescope resolved roughly 30 fragments of the fragile comet on 20 April and 25 pieces on 23 April.

The comet was first discovered in December 2019 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) robotic astronomical survey system in Hawaiʻi, USA. It brightened quickly until mid-March, and some astronomers initially anticipated that it might be visible to the naked eye in May to become one of the most spectacular comets seen in the last two decades. However, the comet abruptly began to get dimmer, leading astronomers to speculate that the icy core may be fragmenting, or even disintegrating. ATLAS’s fragmentation was confirmed by amateur astronomer Jose de Queiroz, who photographed around three pieces of the comet on 11 April.

The Hubble Space Telescope’s new observations of the comet’s breakup on 20 and 23 April reveal that the broken fragments are all enveloped in a sunlight-swept tail of cometary dust. These images provide further evidence that comet fragmentation is probably common and might even be the dominant mechanism by which the solid, icy nuclei of comets die.

“Their appearance changes substantially between the two days, so much so that it's quite difficult to connect the dots,” said David Jewitt of UCLA, leader of one of two teams who imaged the doomed comet with Hubble. “I don’t know whether this is because the individual pieces are flashing on and off as they reflect sunlight, acting like twinkling lights on a Christmas tree, or because different fragments appear on different days.”

“This is really exciting — both because such events are super cool to watch and because they do not happen very often. Most comets that fragment are too dim to see. Events at such scale only happen once or twice a decade," said the leader of the second Hubble observing team, Quanzhi Ye, of the University of Maryland.

Because comet fragmentation happens quickly and unpredictably, reliable observations are rare. Therefore, astronomers remain largely uncertain about the cause of fragmentation. One suggestion is that the original nucleus spins itself into pieces because of the jet action of outgassing from sublimating ices. As this venting is likely not evenly dispersed across the comet, it enhances the breakup. “Further analysis of the Hubble data might be able to show whether or not this mechanism is responsible,” said Jewitt. “Regardless, it's quite special to get a look with Hubble at this dying comet.”

Hubble’s crisp images may yield new clues to the breakup. The telescope has distinguished pieces as small as the size of a house. Before the breakup, the entire nucleus may have been no more than the length of two football fields.

The disintegrating ATLAS comet is currently located inside the orbit of Mars, at a distance of approximately 145 million kilometres from Earth when the latest Hubble observations were taken. The comet will make its closest approach to Earth on 23 May at a distance of approximately 115 million kilometres, and eight days later it will skirt within 37 million kilometres of the Sun.


More Information

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

These observations were made during GO/DD proposal 16111 (D. Jewitt) and GO proposal 16089 (Q. Ye).

Image Credit: NASA, ESA, D. Jewitt (UCLA), Quanzhi Ye (University of Maryland)


Links


Contacts

Quanzhi Ye
University of Maryland
Maryland, USA
Email: qye@astro.umd.edu

David Jewitt
UCLA
Los Angeles, California, USA
Email: djewitt@gmail.com

Bethany Downer
ESA/Hubble, Public Information Officer
Garching, Germany
Email: bethany.downer@partner.eso.org


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Monday, April 27, 2020

Hungry galaxies grow fat on the flesh of their neighbours

Simulation showing distribution of dark matter particles around the galaxy.
Credit: Gupta et al/ASTRO 3D/ IllustrisTNG collaboration

Simulation showing distribution of dark matter density overlayed with the gas density. This image cleanly shows the gas channels connecting the central galaxy with its neighbours. Credit: Gupta et al/ASTRO 3D/ IllustrisTNG collaboration. Hi-res Image

Modelling shows big galaxies get bigger by merging with smaller ones


Galaxies grow large by eating their smaller neighbours, new research reveals.

Exactly how massive galaxies attain their size is poorly understood, not least because they swell over billions of years. But now a combination of observation and modelling from researchers led by Dr Anshu Gupta from Australia’s ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D) has provided a vital clue.

In a paper published in The Astrophysical Journal, the scientists combine data from an Australian project called the Multi-Object Spectroscopic Emission Line (MOSEL) survey with a cosmological modelling program running on some of the world’s largest supercomputers in order to glimpse the forces that create these ancient galactic monsters.

By analysing how gases within galaxies move, Dr Gupta said, it is possible to discover the proportion of stars made internally – and the proportion effectively cannibalised from elsewhere.

“We found that in old massive galaxies – those around 10 billion light years away from us – things move around in lots of different directions,” she said.

“That strongly suggests that many of the stars within them have been acquired from outside. In other words, the big galaxies have been eating the smaller ones.”

Because light takes time to travel through the universe, galaxies further away from the Milky Way are seen at an earlier point in their existence. Dr Gupta’s team found that observation and modelling of these very distant galaxies revealed much less variation in their internal movements.

“We then had to work out why ‘older’, closer big galaxies were so much more disordered than the ‘younger’, more distant ones,” said second author ASTRO 3D’s Dr Kim-Vy Tran, who like Dr Gupta, is based at the UNSW Sydney.

“The most likely explanation is that in the intervening billions of years the surviving galaxies have grown fat and disorderly through incorporating smaller ones. I think of it as big galaxies having a constant case of the cosmic munchies.”

The research team – which included scientists from other Australian universities plus institutions in the US, Canada, Mexico, Belgium and the Netherlands – ran their modelling on a specially designed set of simulations known as IllustrisTNG.

This is a multi-year, international project that aims to build a series of large cosmological models of how galaxies form. The program is so big that it has to run simultaneously on several of world’s most powerful supercomputers.

“The modelling showed that younger galaxies have had less time to merge with other ones,” said Dr Gupta.

“This gives a strong clue to what happens during an important stage of their evolution.”



Paper Details:

Title: MOSEL Survey: Tracking the Growth of Massive Galaxies at 2 < z < 4 Using Kinematics and the IllustrisTNG Simulation

Full Paper

DOI: 10.3847/1538-4357/ab7b6d


Authors:

Anshu Gupta1,2 , Kim-Vy Tran1,2,3, Jonathan Cohn3 , Leo Y. Alcorn3,4 , Tiantian Yuan2,5 , Vicente Rodriguez-Gomez6, Anishya Harshan1 , Ben Forrest7 , Lisa J. Kewley2,8 , Karl Glazebrook5 , Caroline M. Straatman9 , Glenn G. Kacprzak2,5, Themiya Nanayakkara10 , Ivo Labbé5 , Casey Papovich3,11 , and Michael Cowley12,13
  1. School of Physics, University of New South Wales, Sydney, NSW 2052, Australia;
  2. ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), Australia
  3. George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A&M University, College Station, TX 77843-4242, USA
  4. Department of Physics and Astronomy, York University, 4700 Keele Street, Toronto, Ontario, MJ3 1P3, Canada
  5. Swinburne University of Technology, Hawthorn, VIC 3122, Australia
  6. Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, A.P. 72-3, 58089 Morelia, Mexico
  7. Department of Physics & Astronomy, University of California, Riverside, 900 University Avenue, Riverside, CA 92521, USA
  8. Research School of Astronomy and Astrophysics, The Australian National University, Cotter Road, Weston Creek, ACT 2611, Australia
  9. Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281 S9, B-9000 Gent, Belgium
  10. Leiden Observatory, Leiden University, P.O. Box 9513, NL 2300 RA Leiden, The Netherlands
  11. Department of Physics and Astronomy, Texas A&M University, College Station, TX 77843-4242, USA
  12. Centre for Astrophysics, University of Southern Queensland, West Street, Toowoomba, QLD 4350, Australia
  13. School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, QLD 4001, Australia

Funded by:  ASTRO 3D, Australia Research Council, National Science Foundation, Nederlandse Organisatie voor Wetenschappelijk Onderzoek


More about ASTRO 3D:

ASTRO 3D is a seven-year $40 million Centre of Excellence project funded by the Australian Government through the Australian Research Council. The Centre began in June 2017 and will end in June 2024. It hosts around 200 investigators and professional staff, mostly based at six nodes: the Australian National University, Curtin University, Swinburne University of Technology, University of Melbourne, University of Sydney, and University of Western Australia. https://astro3d.org.au/ More about IllustrisTNG

The IllustrisTNG project is an ongoing series of large, cosmological magnetohydrodynamical simulations of galaxy formation. TNG aims to illuminate the physical processes that drive galaxy formation: to understand when and how galaxies evolve into the structures that are observed in the night sky, and to make predictions for current and future observational programs. The simulations use a state of the art numerical code which includes a comprehensive physical model and runs on some of the largest supercomputers in the world. TNG is a successor to the original Illustris simulation and builds on several years of effort by many people. The project description page contains an introduction to the motivations, techniques, and early science results of the TNG simulations. Presently, the project includes three primary runs spanning a range of volume and resolution; these are called TNG50, TNG100, and TNG300. https://www.tng-project.org/

More about the Multi-Object Spectroscopic Emission Line (MOSEL) survey

The MOSEL survey is an ongoing survey of star-forming galaxies around 12 billion light years away. The main objective is identify factors affecting the rise and fall of star formation activity in young galaxies.

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Saturday, April 25, 2020

Hubble Celebrates its 30th Anniversary with a Tapestry of Blazing Starbirth

Tapestry of Blazing Starbirth

Wide-field view of NGC 2014 and NGC 2020 in the Large Magellanic Cloud (Ground-based Image)


Videos

Hubblecast 128: 30 Years of Science with the Hubble Space Telescope
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Hubblecast 129: Hubble’s Collection of Anniversary Images
Hubblecast 129: Hubble’s Collection of Anniversary Images

Zooming Into the Cosmic Reef
Zooming Into the Cosmic Reef

Pan Across the Cosmic Reef
Pan Across the Cosmic Reef

Cosmic Reef for Fulldome
Cosmic Reef for Fulldome

3D Animation of the Cosmic Reef
3D Animation of the Cosmic Reef


Hubble Space Telescope’s iconic images and scientific breakthroughs have redefined our view of the Universe. To commemorate three decades of scientific discoveries, this image is one of the most photogenic examples of the many turbulent stellar nurseries the telescope has observed during its 30-year lifetime. The portrait features the giant nebula NGC 2014 and its neighbour NGC 2020 which together form part of a vast star-forming region in the Large Magellanic Cloud, a satellite galaxy of the Milky Way, approximately 163 000 light-years away. The image is nicknamed the “Cosmic Reef” because it resembles an undersea world.

On 24 April 1990 the Hubble Space Telescope was launched aboard the space shuttle Discovery, along with a five-astronaut crew. Deployed into low-Earth orbit a day later, the telescope has since opened a new eye onto the cosmos that has been transformative for our civilization.

Hubble is revolutionising modern astronomy not only for astronomers, but also by taking the public on a wondrous journey of exploration and discovery. Hubble’s seemingly never-ending, breathtaking celestial snapshots provide a visual shorthand for its exemplary scientific achievements. Unlike any other telescope before it, Hubble has made astronomy relevant, engaging, and accessible for people of all ages. The mission has yielded to date 1.4 million observations and provided data that astronomers around the world have used to write more than 17 000 peer-reviewed scientific publications, making it one of the most prolific space observatories in history. Its rich data archive alone will fuel future astronomy research for generations to come.

Each year, the NASA/ESA Hubble Space Telescope dedicates a small portion of its precious observing time to taking a special anniversary image, showcasing particularly beautiful and meaningful objects. These images continue to challenge scientists with exciting new surprises and to fascinate the public with ever more evocative observations.

This year, Hubble is celebrating this new milestone with a portrait of two colourful nebulae that reveals how energetic, massive stars sculpt their homes of gas and dust. Although NGC 2014 and NGC 2020 appear to be separate in this visible-light image, they are actually part of one giant star formation complex. The star-forming regions seen here are dominated by the glow of stars at least 10 times more massive than our Sun. These stars have short lives of only a few million years, compared to the 10-billion-year lifetime of our Sun.

The sparkling centerpiece of NGC 2014 is a grouping of bright, hefty stars near the centre of the image that has blown away its cocoon of hydrogen gas (coloured red) and dust in which it was born. A torrent of ultraviolet radiation from the star cluster is illuminating the landscape around it. These massive stars also unleash fierce winds that are eroding the gas cloud above and to the right of them. The gas in these areas is less dense, making it easier for the stellar winds to blast through them, creating bubble-like structures reminiscent of brain coral, that have earned the nebula the nickname the “Brain Coral.”

By contrast, the blue-coloured nebula below NGC 2014 has been shaped by one mammoth star that is roughly 200 000 times more luminous than our Sun. It is an example of a rare class of stars called Wolf-Rayet stars. They are thought to be the descendants of the most massive stars. Wolf-Rayet stars are very luminous and have a high rate of mass loss through powerful winds. The star in the Hubble image is 15 times more massive than the Sun and is unleashing powerful winds, which have cleared out the area around it. It has ejected its outer layers of gas, sweeping them around into a cone-like shape, and exposing its searing hot core. The behemoth appears offset from the centre because the telescope is viewing the cone from a slightly tilted angle. In a few million years, the star might become a supernova. The brilliant blue colour of the nebula comes from oxygen gas that is heated to roughly 11 000 degrees Celsius, which is much hotter than the hydrogen gas surrounding it.

Stars, both big and small, are born when clouds of dust and gas collapse because of gravity. As more and more material falls onto the forming star, it finally becomes hot and dense enough at its centre to trigger the nuclear fusion reactions that make stars, including our Sun, shine. Massive stars make up only a few percent of the billions of stars in our Universe. Yet they play a crucial role in shaping our Universe, through stellar winds, supernova explosions, and the production of heavy elements.

“The Hubble Space Telescope has shaped the imagination of truly a whole generation, inspiring not only scientists, but almost everybody,” said Günther Hasinger, Director of Science for the European Space Agency. “It is paramount for the excellent and long-lasting cooperation between NASA and ESA.”


More Information
  • The Hubble Space Telescope is a project of international cooperation between ESA and NASA.
  • This image was taken with the Telescope’s Wide Field Camera 3.
  • Image Credit: NASA, ESA, and STScI


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Friday, April 24, 2020

Star Survives Close Call with a Black Hole

GSN 069
Credit: X-ray: NASA/CXO/CSIC-INTA/G.Miniutti et al.; Illustration: NASA/CXC/M. Weiss;


 A Tour of a Star Survives Close Call with a Black Hole - More Animations


Data from NASA's Chandra X-ray Observatory and ESA's XMM-Newton indicate that a star survived a close call with a black hole, as described in our latest press release. As a red giant star approached a supermassive black hole in the galaxy GSN 069, it was caught in the black hole's gravity. Once captured, the outer layers of the red giant containing hydrogen were stripped off and careened toward the black hole, leaving the core of the star — known as a white dwarf — behind. 

The white dwarf is now in a highly elliptical orbit that completes one cycle about once every 9 hours. As its nearest point in its oval-shaped path, the white dwarf is no more than 15 times the radius of the event horizon — the point of no return — away from the black hole. This artist's illustration shows the white dwarf (on the left) when it is nearing the point of closest approach, and is being stretched by the strong gravity of the black hole (on the far right). The white dwarf should be travelling at a noticeable fraction of the speed of light at this point. At closest approach the black hole pulls material from the white dwarf into an encircling disk. This transfer releases a burst of X-rays that Chandra and XMM-Newton can detect every 9 hours. The inset is a time-lapse of Chandra data taken over a period of about 20 hours on February 14 and 15, 2019, centered on the X-ray source in the middle of GSN 069. The sequence loops to show that the X-ray brightness of the source changes regularly and dramatically over the Chandra observation. The black hole and white dwarf pair should also emit gravitational waves, especially at their nearest point.

Because the white dwarf is so close to the black hole, effects from the Theory of General Relativity mean that the direction of the orbit's axis should rotate with time, or "precess", so that multiple orbits make a rosette-shaped pattern. This rotation should repeat every two days and may be detectable with sufficiently long observations.

Schematic Showing White Dwarf Orbit
Credit: NASA/CXC/M. Weiss

What would be the future of the star and its orbit? The combined effect of gravitational waves and an increase in the star's size as it loses mass should cause the orbit to become more circular and grow in size over time. In this case, the rate of mass loss steadily slows down, and the white dwarf slowly spirals away from the black hole. About a trillion years in the future, the white dwarf could lose enough mass to become a planet with a mass similar to Jupiter.

Astronomers have found many stars that have been completely torn apart by encounters with black holes (so-called tidal disruption events), but there are very few reported cases of near misses, where the star likely survived. Grazing encounters like this should be more common than direct collisions given the statistics of cosmic traffic patterns, but they could easily be missed for a couple of reasons. First, it can take a more massive, surviving star too long to complete an orbit around a black hole for astronomers to see repeated bursts. Another issue is that supermassive black holes that are much more massive than the one in GSN 069 may directly swallow a star rather than the star falling into orbits where they periodically lose mass. In these cases, astronomers wouldn't observe anything.

A paper describing these results by Andrew King (University of Leicester, United Kingdom) appears in the March 2020 issue of the Monthly Notices of the Royal Astronomical Society, and is available online. NASA's Marshall Space Flight Center manages the Chandra program. The Smithsonian Astrophysical Observatory's Chandra X-ray Center controls science and flight operations from Cambridge and Burlington, Massachusetts.

What would be the future of the star and its orbit? The combined effect of gravitational waves and an increase in the star's size as it loses mass should cause the orbit to become more circular and grow in size over time. In this case, the rate of mass loss steadily slows down, and the white dwarf slowly spirals away from the black hole. About a trillion years in the future, the white dwarf could lose enough mass to become a planet with a mass similar to Jupiter.

Astronomers have found many stars that have been completely torn apart by encounters with black holes (so-called tidal disruption events), but there are very few reported cases of near misses, where the star likely survived. Grazing encounters like this should be more common than direct collisions given the statistics of cosmic traffic patterns, but they could easily be missed for a couple of reasons. First, it can take a more massive, surviving star too long to complete an orbit around a black hole for astronomers to see repeated bursts. Another issue is that supermassive black holes that are much more massive than the one in GSN 069 may directly swallow a star rather than the star falling into orbits where they periodically lose mass. In these cases, astronomers wouldn't observe anything.

A paper describing these results by Andrew King (University of Leicester, United Kingdom) appears in the March 2020 issue of the Monthly Notices of the Royal Astronomical Society, and is available online. NASA's Marshall Space Flight Center manages the Chandra program. The Smithsonian Astrophysical Observatory's Chandra X-ray Center controls science and flight operations from Cambridge and Burlington, Massachusetts.

A Quick Look at a Star Survives Close Call with a Black Hole


Source: NASA’s Chandra X-ray Observatory


Fast Facts for GSN 069:

Scale: X-ray image is about 11 arcsec (13,000 light years) across.
Category: Quasars & Active Galaxies, Black Holes
Coordinates (J2000): RA 1h 19m 08.67s | Dec -34° 11´ 30.1"
Constellation: Sculptor
Observation Date: Feb 14, 2019
Observation Time: 16 hours 33 minutes
Obs. ID: 22096
Instrument: ACIS
References: King, A., 2020, MNRAS, 493, L120; arXiv:2002.00970
Color Code: X-ray: red
Distance Estimate: About 250 million light years

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Thursday, April 23, 2020

World's First 3D Simulations Reveal the Physics of Superluminous Supernovae

The nebula phase of the magnetar-powered super-luminous supernova from our 3D simulation. At the moment, the supernova ejecta has expanded to a size similar to the solar system. Large scale mixing appears at the outer and inner region of ejecta. The resulting light curves and spectra are sensitive to the mixing that depends on stellar structure and the physical properties of magnetar. (Image by Ken Chen)

For most of the 20th century, astronomers have scoured the skies for supernovae—the explosive deaths of massive stars—and their remnants in search of clues about the progenitor, the mechanisms that caused it to explode, and the heavy elements created in the process. In fact, these events create most of the cosmic elements that go on to form new stars, galaxies, and life.

Because no one can actually see a supernova up close, researchers rely on supercomputer simulations to give them insights into the physics that ignites and drives the event. Now for the first time ever, an international team of astrophysicists simulated the three-dimensional (3D) physics of superluminous supernovae—which are about a hundred times more luminous than typical supernovae. They achieved this milestone using Lawrence Berkeley National Laboratory’s (Berkeley Lab’s) CASTRO code and supercomputers at the National Energy Research Scientific Computing Center (NERSC). A paper describing their work was published in Astrophysical Journal.

Astronomers have found that these superluminous events occur when a magnetar—the rapidly spinning corpse of a massive star whose magnetic field is trillions of times stronger than Earth’s—is in the center of a young supernova. Radiation released by the magnetar is what amplifies the supernova’s luminosity. But to understand how this happens, researchers need multidimensional simulations.

“To do 3D simulations of magnetar-powered superluminous supernovae, you need a lot of supercomputing power and the right code, one that captures the relevant microphysics,” said Ken Chen, lead author of the paper and an astrophysicist at the Academia Sinica Institute of Astronomy and Astrophysics (ASIAA), Taiwan.

He adds that the numerical simulation required to capture the fluid instabilities of these superluminous events in 3D is very complex and requires a lot of computing power, which is why no one has done it before.

The turbulent core of a magnetar bubble inside the superluminous supernovae. Color coding shows densities. The magnetar is located at the center of this image and two bipolar outflows are emitted from it. The physical size of the outflow is about 10,000 km. (Image by Ken Chen)

Fluid instabilities occur all around us. For instance, if you have a glass of water and put some dye on top, the surface tension of the water will become unstable and the heavier dye will sink to the bottom. Because two fluids are moving past each other, the physics of this instability cannot be captured in one dimension. You need a second or third dimension, perpendicular to height to see all of the instability. At the cosmic scale, fluid instabilities that lead to turbulence and mixing play a critical role in the formation of cosmic objects like galaxies, stars, and supernovae.

“You need to capture physics over a range of scales, from very large to really tiny, in extremely high-resolution to accurately model astrophysical objects like superluminous supernovae. This poses a technical challenge for astrophysicists. We were able to overcome this issue with a new numerical scheme and several million supercomputing hours at NERSC,” said Chen.

For this work, the researchers modeled a supernova remnant approximately 15-billion kilometers wide with a dense 10-kilometer wide magnetar inside. In this system, the simulations show that hydrodynamic instabilities form on two scales in the remnant material. One instability is in the hot bubble energized by the magnetar and the other occurs when the young supernova’s forward shock plows up against ambient gas.

“Both of these fluid instabilities cause more mixing than would normally occur in a typical supernova event, which has significant consequences for the light curves and spectra of superluminous supernovae. None of this would have been captured in a one-dimensional model,” said Chen.

They also found that the magnetar can accelerate calcium and silicon elements that were ejected from the young supernova to velocities of 12,000 kilometers per second, which account for their broadened emission lines in spectral observations. And that even energy from weak magnetars can accelerate elements from the iron group, which are located deep in the supernova remnant, to 5,000 to 7,000 kilometers per second, which explains why iron is observed early in core-collapse supernovae events like SN 1987A. This has been a long-standing mystery in astrophysics.

Turbulent core of magnetar bubble inside the superluminous supernovae. Color coding shows the densities. The magnetar is located at the center of this image. Strong turbulence is caused by the radiation from the central magnetar. (Image by Ken Chen)

“We were the first ones to accurately model a superluminous supernova system in 3D because we were fortunate to have access to NERSC supercomputers,” said Chen. “This facility is an extremely convenient place to do cutting-edge science.”

In addition to Chen, other authors on the paper are Stan Woosley (University of California, Santa Cruz) and Daniel Whalen (University of Portsmouth and University of Vienna). The team also received technical support from staff at NERSC and Berkeley Lab’s Center for Computational Sciences and Engineering (CCSE).

Chen started using NERSC as a graduate student at the University of Minnesota in 2011, then as the IAU-Gruber Fellow in the Department of Astrophysics at UC Santa Cruz before taking positions at the National Astronomical Observatory of Japan, and his current role at ASIAA.

Written by Linda Vu
Contact: CScomms@lbl.gov



About Computing Sciences at Berkeley Lab

The Computing Sciences Area at Lawrence Berkeley National Laboratory provides the computing and networking resources and expertise critical to advancing Department of Energy Office of Science research missions: developing new energy sources, improving energy efficiency, developing new materials, and increasing our understanding of ourselves, our world, and our universe.

Founded in 1931 on the belief that the biggest scientific challenges are best addressed by teams, Lawrence Berkeley National Laboratory and its scientists have been recognized with 13 Nobel Prizes. Today, Berkeley Lab researchers develop sustainable energy and environmental solutions, create useful new materials, advance the frontiers of computing, and probe the mysteries of life, matter, and the universe. Scientists from around the world rely on the Lab’s facilities for their own discovery science. Berkeley Lab is a multiprogram national laboratory, managed by the University of California for the U.S. Department of Energy’s Office of Science.

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Wednesday, April 22, 2020

Hubble Observes Aftermath of Massive Collision

Visualisation of Fomalhaut and Fomalhaut b (Artist’s Impression)

Illustration of Hubble’s Observation of Fomalhaut b’s Expanding Dust Cloud

DSS image of Fomalhaut (ground-based image)

Fomalhaut and Piscis Austrinus (ground-based image)


Videos

Hubblecast 127 Light: The Mysteries of Fomalhaut b
Hubblecast 127 Light: The Mysteries of Fomalhaut b


The Hubble Space Telescope offers insight into the nature of exoplanet Fomalhaut b

What astronomers thought was a planet beyond our solar system, has now seemingly vanished from sight. Astronomers now suggest that a full-grown planet never existed in the first place. The NASA/ESA Hubble Space Telescope had instead observed an expanding cloud of very fine dust particles caused by a titanic collision between two icy asteroid-sized bodies orbiting the bright star Fomalhaut, about 25 light-years from Earth.

“The Fomalhaut system is the ultimate test lab for all of our ideas about how exoplanets and star systems evolve,” said George Rieke of the University of Arizona’s Steward Observatory. “We do have evidence of such collisions in other systems, but none of this magnitude has ever been observed. This is a blueprint for how planets destroy each other.”

The object was previously believed to be a planet, called Fomalhaut b, and was first announced in 2008 based on data taken in 2004 and 2006. It was clearly visible in several years of Hubble observations that revealed it as a moving dot. Unlike other directly imaged exoplanets, nagging puzzles with Fomalhaut b arose early on. The object was unusually bright in visible light, but did not have any detectable infrared heat signature. Astronomers proposed that the added brightness came from a huge shell or ring of dust encircling the object that may have been collision-related. Also, early Hubble observations suggested the object might not be following an elliptical orbit, as planets usually do.

“These collisions are exceedingly rare and so this is a big deal that we actually get to see one,” said András Gáspár of the University of Arizona. “We believe that we were at the right place at the right time to have witnessed such an unlikely event with the Hubble Space Telescope.”

“Our study, which analysed all available archival Hubble data on Fomalhaut b, including the most recent images taken by Hubble, revealed several characteristics that together paint a picture that the planet-sized object may never have existed in the first place,” [1] said Gáspár.

Hubble images from 2014 showed the object had vanished, to the disbelief of the astronomers. Adding to the mystery, earlier images showed the object to continuously fade over time. “Clearly, Fomalhaut b was doing things a bona fide planet should not be doing,” said Gáspár.

The resulting interpretation is that Fomalhaut b is not a planet, but a slowly expanding cloud blasted into space as a result of a collision between two large bodies. Researchers believe the collision occurred not too long prior to the first observations taken in 2004. By now the debris cloud, consisting of dust particles around 1 micron (1/50th the diameter of a human hair), is below Hubble’s detection limit. The dust cloud is estimated to have expanded by now to a size larger than the orbit of Earth around our Sun.

Equally confounding is that the object is not on an elliptical orbit, as expected for planets, but on an escape trajectory, or hyperbolic path. “A recently created massive dust cloud, experiencing considerable radiative forces from the central star Fomalhaut, would be placed on such a trajectory” Gáspár said, “Our model is naturally able to explain all independant observable paramters of the system: its expansion rate, its fading and its trajectory.”

Because Fomalhaut b is presently inside a vast ring of icy debris encircling the star, the colliding bodies were likely a mixture of ice and dust, like the cometary bodies that exist in the Kuiper belt on the outer fringe of our solar system. Gáspár and Rieke estimate that each of these comet-like bodies measured about 200 kilometers across. The also suggest that the Fomalhaut system may experience one of these collision events only every 200 000 years.

Gáspár, Rieke, and other astronomers will also be observing the Fomalhaut system with the upcoming NASA/ESA/CSA James Webb Space Telescope, which is scheduled to launch in 2021.


Notes

[1] The team’s paper “New HST data and modeling reveal a massive planetesimal collision around Fomalhaut” is being published in the Proceedings of the National Academy of Sciences on 20 April 2020.


More information

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

The team of astronomers in this study consists of A. Gáspár and G. Rieke of the University of Arizona, USA.

Image credit: ESA/NASA, M. Kornmesser


Links


Contact

András Gáspár
University of Arizona
Tucson, Arizona, USA

Bethany Downer
ESA/Hubble, Public Information Officer
Garching, Germany

Source: ESA/Hubble/News

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Tuesday, April 21, 2020

ALMA Reveals Unusual Composition of Interstellar Comet 2I/Borisov

ALMA observed hydrogen cyanide gas (HCN, left) and carbon monoxide gas (CO, right) coming out of interstellar comet 2I/Borisov. The ALMA images show that the comet contains an unusually large amount of CO gas. ALMA is the first telescope to measure the gases originating directly from the nucleus of an object that travelled to us from another planetary system. Credit: ALMA (ESO/NAOJ/NRAO), M. Cordiner & S. Milam; NRAO/AUI/NSF, S. Dagnello. Hi-Res File

Artist impression of the interstellar comet 2I/Borisov as it travels through our solar system. This mysterious visitor from the depths of space is the first conclusively identified comet from another star. The comet consists of a loose agglomeration of ices and dust particles, and is likely no more than 3,200 feet across, about the length of nine football fields. Gas is ejected out of the comet as it approaches the Sun and is heated up. Credit: NRAO/AUI/NSF, S. Dagnello. Hi-Res File

2I/Borisov likely formed in extremely cold environment, high amounts of carbon monoxide show A galactic visitor entered our solar system last year – interstellar comet 2I/Borisov. When astronomers pointed the Atacama Large Millimeter/submillimeter Array (ALMA) toward the comet on 15 and 16 December 2019, for the first time they directly observed the chemicals stored inside an object from a planetary system other than our own. This research is published online on 20 April 2020 in the journal Nature Astronomy.

The ALMA observations from a team of international scientists led by Martin Cordiner and Stefanie Milam at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, revealed that the gas coming out of the comet contained unusually high amounts of carbon monoxide (CO). The concentration of CO is higher than anyone has detected in any comet within 2 au from the Sun (within less than 186 million miles, or 300 million kilometers) [1]. 2I/Borisov’s CO concentration was estimated to be between nine and 26 times higher than that of the average solar system comet.

Astronomers are interested to learn more about comets, because these objects spend most of their time at large distances from any star in very cold environments. Unlike planets, their interior compositions have not changed significantly since they were born. Therefore, they could reveal much about the processes that occurred during their birth in protoplanetary disks. “This is the first time we’ve ever looked inside a comet from outside our solar system,” said astrochemist Martin Cordiner, “and it is dramatically different from most other comets we’ve seen before.”

ALMA detected two molecules in the gas ejected by the comet: hydrogen cyanide (HCN) and carbon monoxide (CO). While the team expected to see HCN, which is present in 2I/Borisov at similar amounts to that found in solar system comets, they were surprised to see large amounts of CO. “The comet must have formed from material very rich in CO ice, which is only present at the lowest temperatures found in space, below -420 degrees Fahrenheit (-250 degrees Celsius),” said planetary scientist Stefanie Milam.

“ALMA has been instrumental in transforming our understanding of the nature of cometary material in our own solar system – and now with this unique object coming from our next door neighbors. It is only because of ALMA’s unprecedented sensitivity at submillimeter wavelengths that we are able to characterize the gas coming out of such unique objects,“ said Anthony Remijan of the National Radio Astronomy Observatory in Charlottesville, Virginia and co-author of the paper.

Carbon monoxide is one of the most common molecules in space and is found inside most comets. Yet, there’s a huge variation in the concentration of CO in comets and no one quite knows why. Some of this might be related to where in the solar system a comet was formed; some has to do with how often a comet’s orbit brings it closer to the Sun and leads it to release its more easily evaporated ices.

“If the gases we observed reflect the composition of 2I/Borisov’s birthplace, then it shows that it may have formed in a different way than our own solar system comets, in an extremely cold, outer region of a distant planetary system,” added Cordiner. This region can be compared to the cold region of icy bodies beyond Neptune, called the Kuiper Belt.

The team can only speculate about the kind of star that hosted 2I/Borisov’s planetary system. “Most of the protoplanetary disks observed with ALMA are around younger versions of low-mass stars like the Sun,” said Cordiner. “Many of these disks extend well beyond the region where our own comets are believed to have formed, and contain large amounts of extremely cold gas and dust. It is possible that 2I/Borisov came from one of these larger disks.” Due to its high speed when it traveled through our solar system (33 km/s or 21 miles/s) astronomers suspect that 2I/Borisov was kicked out from its host system, probably by interacting with a passing star or giant planet. It then spent millions or billions of years on a cold, lonely voyage through interstellar space before it was discovered on 30 August 2019 by amateur astronomer Gennady Borisov.

2I/Borisov is only the second interstellar object to be detected in our solar system. The first – 1I/’Oumuamua – was discovered in October 2017, at which point it was already on its way out, making it difficult to reveal details about whether it was a comet, asteroid, or something else. The presence of an active gas and dust coma surrounding 2I/Borisov made it the first confirmed interstellar comet.

Until other interstellar comets are observed, the unusual composition of 2I/Borisov cannot easily be explained and raises more questions than it answers. Is its composition typical of interstellar comets? Will we see more interstellar comets in the coming years with peculiar chemical compositions? What will they reveal about how planets form in other star systems?

“2I/Borisov gave us the first glimpse into the chemistry that shaped another planetary system,” said Milam. “But only when we can compare the object to other interstellar comets, will we learn whether 2I/Borisov is a special case, or if every interstellar object has unusually high levels of CO.”

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.



Note 

 [1] One comet known as C/2016 R2 (PanSTARRS), which came from the Oort Cloud, had even higher levels of CO than Borisov when it was at a distance of 2.8 au from the Sun.


Media contact:

Iris Nijman
News and Public Information Manager
National Radio Astronomy Observatory (NRAO)
inijman@nrao.edu
+1 (434) 249-3423


This research was presented in a paper titled “Unusually high CO abundance of the first active interstellar comet,” by M. Cordiner & S. Milam, et al., appearing in the journal Nature Astronomy (DOI: 10.1038/s41550-020-1087-2).

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of the European Organisation for Astronomical Research in the Southern Hemisphere (ESO), the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the Ministry of Science and Technology (MOST) and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).

ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

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