NASA Images Help Explain Eating Habits of Massive Black Hole

This image of the Andromeda galaxy uses data from NASA’s retired Spitzer Space Telescope. Multiple wavelengths are shown, revealing stars, dust, and areas of star formation.

Data from NASA's retired Spitzer Space Telescope has given scientists new insights into why some supermassive black holes shine differently than others.

In images from NASA's retired Spitzer Space Telescope, streams of dust thousands of light-years long flow toward the supermassive black hole at the heart of the Andromeda galaxy. It turns out these streams can help explain how black holes billions of times the mass of our Sun satiate their big appetites but remain "quiet" eaters.

As supermassive black holes gobble up gas and dust, the material gets heated up just before it falls in, creating incredible light shows — sometimes brighter than an entire galaxy full of stars. When the material is consumed in clumps of different sizes, the brightness of the black hole fluctuates.

But the black holes at the center of the Milky Way (Earth's home galaxy) and Andromeda (one of our nearest galactic neighbors) are among the quietest eaters in the universe. What little light they emit does not vary significantly in brightness, suggesting they are consuming a small but steady flow of food, rather than large clumps. The streams approach the black hole little by little, and in a spiral, similar to the way the water swirls down a drain.

Hunting for Andromeda's Food Source

A study published earlier this year took the hypothesis that a quiet supermassive black hole feeds on a steady stream of gas and applied it to the Andromeda galaxy. Using computer models, the authors simulated how gas and dust in proximity to Andromeda's supermassive black hole might behave over time. The simulation demonstrated that a small disk of hot gas could form close to the supermassive black hole and feed it continuously. The disk could be replenished and maintained by numerous streams of gas and dust.

But the researchers also found that those streams have to stay within a particular size and flow rate; otherwise, the matter would fall into the black hole in irregular clumps, causing more light fluctuation.

This close-up view of the center of the Andromeda galaxy, taken by NASA’s retired Spitzer Space Telescope, is annotated with blue dotted lines to highlight the path of two dust streams flowing toward the supermassive black hole at the galaxy’s center (indicated by a purple dot). Hi-res image

When the authors compared their findings to data from Spitzer and NASA's Hubble Space Telescope, they found spirals of dust previously identified by Spitzer that fit within these constraints. From this, the authors concluded that the spirals are feeding Andromeda's supermassive black hole.

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

A Deeper Look at Andromeda

Launched in 2003 and managed by NASA's Jet Propulsion Laboratory, Spitzer studied the universe in infrared light, which is invisible to human eyes. Different wavelengths reveal different features of Andromeda, including hotter sources of light, like stars, and cooler sources, like dust.

By separating these wavelengths and looking at the dust alone, astronomers can see the galaxy's "skeleton" — places where gas has coalesced and cooled, sometimes forming dust, creating conditions for stars to form. This view of Andromeda revealed a few surprises. For instance, although it is a spiral galaxy like the Milky Way, Andromeda is dominated by a large dust ring rather than distinct arms circling its center. The images also revealed a secondary hole in one portion of the ring where a dwarf galaxy passed through.

Andromeda's proximity to the Milky Way means it looks larger than other galaxies from Earth: Seen with the naked eye, Andromeda would be about six times the width of the Moon (about 3 degrees). Even with a field of view wider than Hubble's, Spitzer had to take 11,000 snapshots to create this comprehensive picture of Andromeda.

Source: Spitzer Space Telescope/News

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More About the Mission

JPL managed the Spitzer Space Telescope mission for NASA's Science Mission Directorate in Washington until the mission was retired in January 2020. Science operations were conducted at the Spitzer Science Center at Caltech. Spacecraft operations were based at Lockheed Martin Space in Littleton, Colorado. Data are archived at the Infrared Science Archive operated by IPAC at Caltech. Caltech manages JPL for NASA.

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News Media Contact:

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

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Observers measure how Andromeda’s central black hole is fed

The long way needed to feed the black hole of Andromeda: from 6500 light years down to its door. The image shows the majestic of this galaxy with its many spiral arms filled with millions of stars. In the centre of the galaxy there is a supermassive black hole (small square in the image). A zoom up in this inset is bellow. It depicts long, narrow features circularising towards the centre. These are filaments of dust and gas which is being pulled into to the black hole. A further zoom of the zone (right image) shows the filaments targeting with precision the black hole location. Credit: Spitzer Space Telescope

A team of scientists led by the Observatory of Munich University and the Instituto de Astrofísica de Canarias have obtained direct visualization of the process of feeding the supermassive black hole at the centre of the Andromeda galaxy. The study reveals the existence of long filamentary structures of gas and dust which move in a spiral starting at a distance from the black hole and ending up at the black hole itself. The results, which have been published in the Astrophysical Journal, were obtained using images from the Hubble and Spitzer space telescopes.

The Andromeda Galaxy, which is visible to the naked eye, is one of the nearest galaxies to the Milky Way. In its centre it houses a very massive black hole, which has a mass more than 100 million times that of the Sun. Even so, this black hole, as well as the one at the centre of our own galaxy called Sagittarius A* are among the least active known of the supermassive black holes at galaxy centres: they emit very little radiation.

The activity of a black hole depends on how it is being “fed”, that is to say on how the material which falls into it gets closer as it falls. It is hard to track this in the Milky Way because of our position very close to the plane of the Galaxy, where dust obscuration is very high, and the field is crowded with stars, but the situation with Andromeda is different, and we can observe the black hole with much less impediment.

Now, by combining observations from the Hubble Space Telescope and the Spitzer Space Telescoope, a team of scientists, led by the group of Computational Astrophysics from the Munich University Observatory (USM) and the Instituto de Astrofísica de Canarias (IAC) has been able to study in detail how the black hole of the Andromeda galaxy is carefully fed.

“Black holes are greedy feeders, but nevertheless sensitive” explains Christian Alig, a researcher at the USM who is the first author of the article. “When they are fed slowly and bit by bit they don’t show signs of feeding, but if the feeding is forced and excessive they react violently and aggressively.”

Filaments of material and spiral trajectories

Thanks to the two powerful space telescope the team has discovered that the black hole at the centre of Andromeda feeds by way of long filaments of dust and gas, starting some way from the centre of the galaxy. “The filaments approach the black hole little by little, and in a spiral, similarly to the way the water goes down the hole in the sink” explains Almudena Prieto, a researcher at the IAC who is a co-author of the paper.

Using powerful computers it has been possible to simulate the transport and whereabouts of this material through time and space. The image shows snapshots of the path versus time (indicated in the upper panels in units of millions of years) increasing from left to right. The network of paths, or filaments (streaks of colour in each image) appears to get more complicated as they approach the centre of the galaxy. However the motion is ordered and progressive, with the filaments rotating slowly in a spiral towards the black hole. The journey lasts for over 100 million years.

While the Hubble can see the darkening produced by the dust of the filaments in visible light, the Spitzer telescope can pick out the same filaments in the infrared. Using joint observations with the both telescopes has revealed a complete view of the accretion process of the material around the black hole. Because the Andromeda galaxy is so near, the Spitzer observations of its centre are the most detailed observations of the centre of a galaxy made with this telescope until now, and have a level of precision comparable to that achieved by the Hubble Space Telescope.

This study is part of the PARSEC project, whose aim is to investigate over a wide range of wavelengths, the nuclei of the nearest galaxies, and the accretion processes of their central black holes. Led by the IAC the project has almost 50 members in institutions in a large number of countries.

Article: C. Alig, A. Prieto et al. “The Accretion Mode in Sub-Eddington Supermassive Black Holes: Getting into the Central Parsecs of Andromeda”. 2023 ApJ 953 109. DOI: 10.3847/1538-4357/ace2c3

Contact at the IAC:
Almudena Prieto, almudena.prieto@iac.es

Source: Spitzer Space Telescope/News

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An Accidental Discovery Hints at a Hidden Population of Cosmic Objects

This mosaic shows the entire sky imaged by the Wide-field Infrared Survey Explorer (WISE). Infrared light refers to wavelengths that are longer than those visible to the human eye. Many cosmic objects radiate infrared, including gas and dust clouds where stars form, and brown dwarfs. Credit: NASA/JPL-Caltech/UCLA 

A new studyoffers a tantalizing explanation for how a peculiar cosmic object called WISEA J153429.75-104303.3 – nicknamed “The Accident” – came to be. The Accident is a brown dwarf. Though they form like stars, these objects don’t have enough mass to kickstart nuclear fusion, the process that causes stars to shine. And while brown dwarfs sometimes defy characterization, astronomers have a good grasp on their general characteristics.

Or they did, until they found this one.

The Accident got its name after being discovered by sheer luck. It slipped past normal searches because it doesn’t resemble any of the just over 2,000 brown dwarfs that have been found in our galaxy so far.

Can you see the dark spot moving in the bottom left corner of the screen? It’s a brown dwarf nicknamed “The Accident,” which was discovered by citizen scientist Dan Caselden. It had slipped past typical searches because it doesn’t look like any other known brown dwarfs. Credit: NASA/JPL-Caltech/Dan Caselden. Images

As brown dwarfs age, they cool off, and their brightness in different wavelengths of light changes. It’s not unlike how some metals, when heated, go from bright white to deep red as they cool. The Accident confused scientists because it was faint in some key wavelengths, suggesting it was very cold (and old), but bright in others, indicating a higher temperature.

“This object defied all our expectations,” said Davy Kirkpatrick, an astrophysicist at IPAC at Caltech in Pasadena, California. He and his co-authors posit in their new study, appearing in the Astrophysical Journal Letters, that The Accident might be 10 billion to 13 billion years old – at least double the median age of other known brown dwarfs. That means it would have formed when our galaxy was much younger and had a different chemical makeup. If that’s the case, there are likely many more of these ancient brown dwarfs lurking in our galactic neighborhood.

A Peculiar Profile

The Accident was first spotted by NASA’s Near-Earth Object Wide-Field Infrared Survey Explorer (NEOWISE), launched in 2009 under the moniker WISE and managed by NASA’s Jet Propulsion Laboratory in Southern California. Because brown dwarfs are relatively cool objects, they radiate mostly infrared light, or wavelengths longer than what the human eye can see.

Brown dwarfs share certain characteristics with both stars and planets. Generally, they are less massive than stars and more massive than planets. A brown dwarf becomes a star if its core pressure gets high enough to start nuclear fusion, the process that causes stars to shine. Credit: NASA/JPL-Caltech

To figure out how The Accident could have such seemingly contradictory properties – some suggesting it is very cold, others indicating it is much warmer – the scientists needed more information. So they observed it in additional infrared wavelengths with a ground-based telescope at the W. M. Keck Observatory in Hawaii. But the brown dwarf appeared so faint in those wavelengths, they couldn’t detect it at all, apparently confirming their suggestion that it was very cold.

They next set out to determine if the dimness resulted from The Accident being farther than expected from Earth. But that wasn’t the case, according to precise distance measurements by NASA’s Hubble and Spitzer Space Telescopes. Having determined the object’s distance – about 50 light-years from Earth – the team realized that it is moving fast – about half a million miles per hour (800,000 kph). That’s much faster than all other brown dwarfs known to be at this distance from Earth, which means it has probably been careening around the galaxy for a long time, encountering massive objects that accelerate it with their gravity.

With a mound of evidence suggesting The Accident is extremely old, the researchers propose that its strange properties aren’t strange at all and that they may be a clue to its age.

When the Milky Way formed about 13.6 billion years ago, it was composed almost entirely of hydrogen and helium. Other elements, like carbon, formed inside stars; when the most massive stars exploded as supernovae, they scattered the elements throughout the galaxy.

Methane, composed of hydrogen and carbon, is common in most brown dwarfs that have a temperature similar to The Accident. But The Accident’s light profile suggests it contains very little methane. Like all molecules, methane absorbs specific wavelengths of light, so a methane-rich brown dwarf would be dim in those wavelengths. The Accident, by contrast, is bright in those wavelengths, which could indicate low levels of methane.

Thus, the light profile of The Accident could match that of a very old brown dwarf that formed when the galaxy was still carbon poor; very little carbon at formation means very little methane in its atmosphere today.

“It’s not a surprise to find a brown dwarf this old, but it is a surprise to find one in our backyard,” said Federico Marocco, an astrophysicist at IPAC at Caltech who led the new observations using the Keck and Hubble telescopes. “We expected that brown dwarfs this old exist, but we also expected them to be incredibly rare. The chance of finding one so close to the solar system could be a lucky coincidence, or it tells us that they’re more common than we thought.”

This artist’s illustration shows a dim, cold brown dwarf in space. Brown dwarfs form like stars, but do not have enough mass to ignite nuclear fusion in their cores – the process that causes stars to burn. As a result they share some physical characteristics with massive planets, like Jupiter. Credit: IPAC/Caltech

A Lucky Accident

To find more ancient brown dwarfs like The Accident – if they’re out there – researchers might have to change how they search for these objects.

The Accident was discovered by citizen scientist Dan Caselden, who was using an online program he built to find brown dwarfs in NEOWISE data. The sky is full of objects that radiate infrared light; by and large, these objects appear to remain fixed in the sky, due to their great distance from Earth. But because brown dwarfs are so faint, they are visible only when they’re relatively close to Earth, and that means scientists can observe them moving across the sky over months or years. (NEOWISE maps the entire sky about once every six months.)

Caselden’s program attempted to remove the stationary infrared objects (like distant stars) from the NEOWISE maps and highlight moving objects that had similar characteristics to known brown dwarfs. He was looking at one such brown dwarf candidate when he spotted another, much fainter object moving quickly across the screen. This would turn out to be WISEA J153429.75-104303.3, which hadn’t been highlighted because it did not match the program’s profile of a brown dwarf. Caselden caught it by accident.

“This discovery is telling us that there’s more variety in brown dwarf compositions than we’ve seen so far,” said Kirkpatrick. “There are likely more weird ones out there, and we need to think about how to look for them.”

Source:  Spitzer Space Telescope/News

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More About the Missions

Launched in 2009, the WISE spacecraft was placed into hibernation in 2011 after completing its primary mission. In September 2013, NASA reactivated the spacecraft with the primary goal of scanning for near-Earth objects, or NEOs, and the mission and spacecraft were renamed NEOWISE. JPL, a division of Caltech, managed and operated WISE for NASA’s Science Mission Directorate (SMD). The mission was selected competitively under NASA’s Explorers Program managed by the agency’s Goddard Space Flight Center in Greenbelt, Maryland. NEOWISE is a project of JPL, a division of Caltech, and the University of Arizona, supported by NASA’s Planetary Defense Coordination Office.

For more information about WISE, go to: https://www.nasa.gov/mission_pages/WISE/main/index.html

JPL managed Spitzer mission operations for NASA’s SMD until the spacecraft was retired in 2020. Science operations were conducted at the Spitzer Science Center at IPAC at Caltech. Spacecraft operations were based at Lockheed Martin Space in Littleton, Colorado. The Spitzer data archive is housed at the Infrared Science Archive at IPAC at Caltech.

For more information about NASA’s Spitzer mission, go to:

https://www.nasa.gov/mission_pages/spitzer/main/index.html  /  https://www.ipac.caltech.edu/project/spitzer

The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington.

For more information about NASA’s Hubble, go to:https://www.nasa.gov/mission_pages/hubble/main/index.html

For more opportunities to participate in NASA Citizen Science Projects, go to: https://science.nasa.gov/citizenscience

 

News Media Contact

Calla Cofield

Jet Propulsion Laboratory, Pasadena, Calif.

626-808-2469

calla.e.cofield@jpl.nasa.gov

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NASA Spots Giant Debris Cloud Created by Clashing Celestial Bodies

Planetesimal Collision Around Star HD 166191 (Illustration)

This illustration depicts the result of a collision between two large asteroid-sized bodies. NASA's Spitzer saw a debris cloud block the star HD 166191, giving scientists details about the smashup that occurred. Credit: NASA/JPL-Caltech

Major smashups between rocky bodies shaped our solar system. Observations of a similar crash give clues about how frequent these events are around other stars.

Most of the rocky planets and satellites in our solar system, including Earth and the Moon, were formed or shaped by massive collisions early in the solar system’s history. By smashing together, rocky bodies can accumulate more material, increasing in size, or they can break apart into multiple smaller bodies.

Astronomers using NASA’s now-retired Spitzer Space Telescope have in the past found evidence of these types of collisions around young stars where rocky planets are forming. But those observations didn’t provide many details about the smashups, such as the size of the objects involved.

In a new study in the Astrophysical Journal, a group of astronomers led by Kate Su of the University of Arizona report the first observations of a debris cloud from one of these collisions as it passed in front of its star and briefly blocked the light. Astronomers call this a transit. Coupled with knowledge about the star’s size and brightness, the observations enabled the researchers to directly determine the size of the cloud shortly after impact, estimate the size of the objects that collided, and watch the speed with which the cloud dispersed.

“There is no substitute for being an eyewitness to an event,” said George Rieke, also at the University of Arizona and a coauthor of the new study. “All the cases reported previously from Spitzer have been unresolved, with only theoretical hypotheses about what the actual event and debris cloud might have looked like.”

Beginning in 2015, a team led by Su started making routine observations of a 10 million-year-old star called HD 166191. Around this early time in a star’s life, dust left over from its formation has clumped together to form rocky bodies called planetesimals – seeds of future planets. Once the gas that previously filled the space between those objects has dispersed, catastrophic collisions between them become common.

Anticipating they might see evidence of one of these collisions around HD 166191, the team used Spitzer to conduct more than 100 observations of the system between 2015 and 2019. While the planetesimals are too small and distant to resolve by telescope, their smashups produce large amounts of dust. Spitzer detected infrared light – or wavelengths slightly longer than what human eyes can see. Infrared is ideal for detecting dust, including the debris created by protoplanet collisions.

In mid-2018, the space telescope saw the HD 166191 system become significantly brighter, suggesting an increase in debris production. During that time, Spitzer also detected a debris cloud blocking the star. Combining Spitzer’s observation of the transit with observations by telescopes on the ground, the team could deduce the size and shape of the debris cloud.

Their work suggests the cloud was highly elongated, with a minimum estimated area three times that of the star. However, the amount of infrared brightening Spitzer saw suggests only a small portion of the cloud passed in front of the star and that the debris from this event covered an area hundreds of times larger than that of the star.

To produce a cloud that big, the objects in the main collision must have been the size of dwarf planets, like Vesta in our solar system – an object 330 miles (530 kilometers) wide located in the main asteroid belt between Mars and Jupiter. The initial clash generated enough energy and heat to vaporize some of the material. It also set off a chain reaction of impacts between fragments from the first collision and other small bodies in the system, which likely created a significant amount of the dust Spitzer saw.

Over the next few months, the large dust cloud grew in size and became more translucent, indicating that the dust and other debris were quickly dispersing throughout the young star system. By 2019, the cloud that passed in front of the star was no longer visible, but the system contained twice as much dust as it had before Spitzer spotted the cloud. This information, according to the paper’s authors, can help scientists test theories about how terrestrial planets form and grow.

“By looking at dusty debris disks around young stars, we can essentially look back in time and see the processes that may have shaped our own solar system,” said Su. “Learning about the outcome of collisions in these systems, we may also get a better idea of how frequently rocky planets form around other stars.”

More About Spitzer

The entire body of scientific data collected by Spitzer during its lifetime is available to the public via the Spitzer data archive, housed at the Infrared Science Archive at IPAC at Caltech in Pasadena, California. JPL, a division of Caltech, 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.

For more information about NASA’s Spitzer mission, go to: https://www.jpl.nasa.gov/missions/spitzer-space-telescope and https://www.ipac.caltech.edu/project/spitzer

News Media Contact

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

Source:  Spitzer Space Telescope/News

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Data reveals evidence of molecular absorption in the atmosphere of a hot Neptune

LTT9779b

Source: http://news.unm.edu/news/data-reveals-evidence-of-molecular-absorption-in-the-atmosphere-of-a-hot-neptune

An international team of scientists recently measured the spectrum of the atmosphere of a rare hot Neptune exoplanet, whose discovery by NASA's Transiting Exoplanet Survey Satellite (TESS) was announced just last month.  

The discovery was made with data provided from the now-retired NASA Spitzer Space Telescope, which allows a unique, infrared view of the universe to look into regions of space that are hidden from optical telescopes.

One of the main goals of NASA’s TESS mission is to find new, small planets that would be good targets for atmospheric characterization. Early in its mission, it found LTT9779b, a planet orbiting a Sun-like star located 260 light years away from Earth. This planet, a little larger than Neptune, orbits very close to its star. The planet is found in the "hot Neptune desert," where planets shouldn't exist. Indeed, most close-in hot exoplanets are either gas giants the size of Jupiter or Saturn that have enough mass to retain most of their atmosphere using their high gravity against the evaporation caused by the star, or small rocky exoplanets that have lost their atmosphere to the star long ago.

“This ultra-hot Neptune is a ‘medium-sized’ exoplanet that orbits very close to its star (it takes just 19 hours to complete an orbit), but its low density indicates that it still has an atmosphere weighing at least 10 percent of the planet’s mass,” explained University of New Mexico Physics and Astronomy Assistant Professor Diana Dragomir, who is leading the work which involved more than 25 institutions.

The age of this system is 2 billion years. At this high temperature, the planet’s atmosphere should have evaporated long ago, early in the system’s life. “Hot Neptunes are rare, and one in such an extreme environment as this one is difficult to explain because its mass isn’t large enough to hold on to an atmosphere for very long. So how did it manage? LTT9779b had us scratching our heads, but the fact that it has an atmosphere gives us a rare way to investigate this type of planet, so we decided to probe it with another telescope,” Dragomir added.

To investigate its atmospheric composition and shed further light on its origin, scientists obtained secondary eclipse observations with the Spitzer Infrared Array Camera (IRAC) of the hot Neptune. The Spitzer observations confirmed an atmospheric presence and enabled a measurement of the planet's very high temperature, approximately 2,000 Kelvin (about 3,000 degrees Fahrenheit). “For the first time, we measured light coming from a planet that shouldn’t exist!” Said Dragomir.

After combining the Spitzer observations with a measurement of the secondary eclipse in the TESS bandpass, the scientists studied the resulting emission spectrum and identified evidence of molecular absorption in the planet’s atmosphere, which they believe is likely due to carbon monoxide. This molecule is not unexpected in the atmospheres of hot large planets (hot Jupiters), but to find it in a hot Neptune may provide clues on the origin of this planet and how it managed to hold onto its atmosphere. This result constitutes the first detection of atmospheric features in an exoplanet discovered by TESS, and the first-ever for an ultra-hot Neptune.

“If there’s a lot of atmosphere surrounding the planet, as is the case for \, then you can study it more easily,” said Dragomir. “A smaller atmosphere would be much harder to observe.” The results indicate that LTT9779b is an excellent target for additional characterization with NASA’s upcoming James Webb Space Telescope (JWST), which could also verify whether the observed molecular absorption is indeed due to carbon monoxide.

A companion paper, led by Kansas University Assistant Professor Ian Crossfield, also found signs that point to the planet’s atmosphere having a higher level of heavy elements than expected. This is additionally intriguing because the two similarly-sized planets in our Solar System, Neptune and Uranus, are primarily composed of light elements like hydrogen and helium.

“LTT9779 is one of those super-exciting targets, a very rare gemstone for our understanding of hot Neptunes. We believe we detected carbon-monoxide in its atmosphere and that the permanent dayside is very hot, while very little heat is transported to the night side,” said Björn Benneke, professor at Université de Montréal and member of the Institute for Research on exoplanets (iREx). “Both findings make LTT9779b say that there is a very strong signal to be observed making the planet a very intriguing target for future detailed characterization with JWST.”

Together, these results set the stage for similar investigations of a larger sample of exoplanets discovered in this hot Neptune desert, which are key to uncovering the origin of this unique population of exoplanets.

The research, Spitzer Reveals Evidence of Molecular Absorption in the Atmosphere of the Hot Neptune LTT 9779b, was published in The Astrophysical Journal Letters and supported in part by NASA through a Caltech/Jet Propulsion Laboratory (JPL) grant.

** A companion paper and press release is related to this research and should also be reviewed as part of any media interest. The press release, from Kansas University, is titled ‘Hot Neptune’ 260 light years away that ‘shouldn’t exist.’

Source: NASAS"s Spitzer Space Telescope/News

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Spitzer Studies a Stellar Playground With a Long History

A collection of gas and dust over 500 light-years across, the Perseus Molecular Cloud hosts an abundance of young stars. It was imaged here by the NASA's Spitzer Space Telescope.Credit: NASA/JPL-Caltec. › Full image and caption

This image from NASA's Spitzer Space Telescope shows the Perseus Molecular Cloud, a massive collection of gas and dust that stretches over 500 light-years across. Home to an abundance of young stars, it has drawn the attention of astronomers for decades.

Spitzer's Multiband Imaging Photometer (MIPS) instrument took this image during Spitzer's "cold mission," which ran from the spacecraft's launch in 2003 until 2009, when the space telescope exhausted its supply of liquid helium coolant. (This marked the beginning of Spitzer's "warm mission.") Infrared light can't be seen by the human eye, but warm objects, from human bodies to interstellar dust clouds, emit infrared light.

Infrared radiation from warm dust generates much of the glow seen here from the Perseus Molecular Cloud. Clusters of stars, such as the bright spot near the left side of the image, generate even more infrared light and illuminate the surrounding clouds like the Sun lighting up a cloudy sky at sunset. Much of the dust seen here emits little to no visible light (in fact, the dust blocks visible light) and is therefore revealed most clearly with infrared observatories like Spitzer.

On the right side of the image is a bright clump of young stars known as NGC 1333, which Spitzer has observed multiple times. It is located about 1,000 light-years from Earth. That sounds far, but it is close compared to the size of our galaxy, which is about 100,000 light-years across. NGC 1333's proximity and strong infrared emissions made it visible to astronomers using some of the earliest infrared instruments.

This image from NASA'S Spitzer Space Telescope shows the location and apparent size of the Perseus Molecular Cloud in the night sky. Located on the edge of the Perseus Constellation, the collection of gas and dust is about 1,000 light-years from Earth and about 500 light-years wide.

Credit: NASA/JPL-Caltech.  Full image and caption

In fact, some of its stars were first observed in the mid-1980s with the Infrared Astronomical Survey (IRAS), a joint mission between NASA, the United Kingdom and the Netherlands. The first infrared satellite telescope, it observed the sky in infrared wavelengths blocked by Earth's atmosphere, providing the first-ever view of the universe in those wavelengths. 

More than 1,200 peer-reviewed research papers have been written about NGC 1333, and it has been studied in other wavelengths of light, including by the Hubble Space Telescope, which detects mostly visible light, and the Chandra X-Ray Observatory. 

Many young stars in the cluster are sending massive outflows of material - the same material that forms the star - into space. As the material is ejected, it is heated up and smashes into the surrounding interstellar medium. These factors cause the jets to radiate brightly, and they can be seen in close-up studies of the region. This has provided astronomers with a clear glimpse of how stars go from a sometimes-turbulent adolescence into calmer adulthood.

An Evolving Mystery

Other clusters of stars seen below NGC 1333 in this image have posed a fascinating mystery for astronomers: They appear to contain stellar infants, adolescents and adults. Such a closely packed mixture of ages is extremely odd, according to Luisa Rebull, an astrophysicist at NASA's Infrared Science Archive at Caltech-IPAC who has studied NGC 1333 and some of the clusters below it. Although many stellar siblings may form together in tight clusters, stars are always moving, and as they grow older they tend to move farther and farther apart.

This annotated image of the Perseus Molecular Cloud, provided by NASA's Spitzer Space Telescope, shows the location of various star clusters, including NGC 1333.  Credit: NASA/JPL-Caltech..  Full image and caption

Finding such a closely packed mixture of apparent ages doesn't fit with current ideas about how stars evolve. "This region is telling astronomers that there's something we don't understand about star formation," said Rebull. The puzzle presented by this region is one thing that keeps astronomers coming back to it. "It's one of my favorite regions to study," she added. 

Since IRAS's early observations, the region has come into clearer focus, a process that is common in astronomy, said Rebull. New instruments bring more sensitivity and new techniques, and the story becomes clearer with each new generation of observatories. On Jan. 30, 2020, NASA will decommission the Spitzer Space Telescope, but its legacy has paved the way for upcoming observatories, including the James Webb Space Telescope, which will also observe infrared light.

The Spitzer-MIPS data used for this image is at the infrared wavelength of 24 microns. Small gaps along the edges of this image not observed by Spitzer were filled in using 22-micron data from NASA's Wide-Field Infrared Survey Explorer (WISE).

To learn more about Spitzer and how it studies the infrared universe, check out the Spitzer 360 VR experience, now available on the NASA Spitzer channel on YouTube: http://bit.ly/SpitzerVR.

More information about Spitzer is available at the following site(s):   https://www.nasa.gov/mission_pages/spitzer/main

News Media Contact

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

Source:   JPL-Caltec/News

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Spitzer Spots a Starry Region Bursting With Bubbles

Bubbles, Bubbles Everywhere! (Annotated)
Credit: NASA/JPL-Caltech/Milky Way Project

This infrared image from NASA's Spitzer Space Telescope shows a cloud of gas and dust full of bubbles, which are inflated by wind and radiation from young, massive stars. Each bubble is filled with hundreds to thousands of stars, which form from dense clouds of gas and dust. The bubbles are estimated to be 10 to 30 light-years across, based on what astronomers know about them and other cosmic bubbles. However, determining the exact sizes of individual bubbles can be difficult, because their distance from Earth is challenging to measure and objects appear smaller the farther away they are. Flows of particles emitted by the stars, called stellar winds, as well as the pressure of the light the stars produce, can push the surrounding material outward, sometimes creating a distinct perimeter. In the annotated image below, the yellow circles and ovals outline more than 30 bubbles.

Bubbles, Bubbles Everywhere! (Annotated)
Credit: NASA/JPL-Caltech/Milky Way Project

This active region of star formation is located within the Milky Way galaxy, in the constellation Aquila (also known as the Eagle). Black veins running throughout the cloud are regions of especially dense cold dust and gas where even more new stars are likely to form. 

Spitzer sees infrared light, which isn't visible to the human eye. Many interstellar nebulas (clouds of gas and dust in space) like this one are best observed in infrared light because infrared wavelengths can pass through intervening layers of dust in the Milky Way galaxy. Visible light, however, tends to be blocked more by dust. 

The colors in this image represent different wavelengths of infrared light. Blue represents a wavelength of light primarily emitted by stars; dust and organic molecules called hydrocarbons appear green, and warm dust that's been heated by stars appears red. 

Also visible are four bow shocks — red arcs of warm dust formed as winds from fast-moving stars push aside dust grains scattered sparsely through most of the nebula. The locations of the bow shocks are indicated by squares in the annotated image above and shown close up in the images below.

Bow Shocks Between the Bubbles

These four images show bow shocks, or arcs of warm dust formed as winds from fast-moving stars push aside dust grains scattered sparsely through most of the nebula.  Credit: NASA/JPL-Caltech/Milky Way Project

The bubbles and bow shocks in these images were identified as part of The Milky Way Project, a citizen science initiative on Zooniverse.org that seeks to map star formation throughout the galaxy. Participating citizen scientists looked through images from Spitzer's public data archive and identified as many bubbles as they could. More than 78,000 unique user accounts contributed. Astronomers running this program recently published a catalog of the bubble candidates that multiple citizen scientists had identified. The full Milky Way Project catalogs, which list a total of 2,600 bubbles and 599 bow shocks, are described in a paper published recently in Monthly Notices of the Royal Astronomical Society.

NASA's Jet Propulsion Laboratory, Pasadena, California, manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate in Washington. Science operations are conducted at the Spitzer Science Center at Caltech in Pasadena. Space operations are based at Lockheed Martin Space in Littleton, Colorado. Data are archived at the Infrared Science Archive housed at IPAC at Caltech. Caltech manages JPL for NASA.

News Media Contact

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

Source: JPL-Caltech/Spitzer/News

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NASA's Spitzer Captures Stellar Family Portrait

Cepheus B • Cepheus C • V374 Ceph

 Credit: NASA/JPL-Caltech

Image1 - Image2 - Image3 - Image 4

This image was compiled using data from NASA's Spitzer Space Telescope using the Infrared Array Camera (IRAC) and the Multiband Imaging Photometer (MIPS) during Spitzer's "cold" mission, before the spacecraft's liquid helium coolant ran out in 2009. The colors correspond with IRAC wavelengths of 3.6 microns (blue), 4.5 microns (cyan) and 8 microns (green), and 24 microns (red) from the MIPS instrument.

The green-and-orange delta filling most of this image is a nebula, or a cloud of gas and dust. This region formed from a much larger cloud of gas and dust that has been carved away by radiation from stars.

The bright region at the tip of the nebula is dust that has been heated by the stars' radiation, which creates the surrounding red glow. The white color is the combination of four colors (blue, green, orange and red), each representing a different wavelength of infrared light, which is invisible to human eyes.

The massive stars illuminating this region belong to a star cluster that extends above the white spot.

On the left side of this image, a dark filament runs horizontally through the green cloud. A smattering of baby stars (the red and yellow dots) appear inside it. Known as Cepheus C, the area is a particularly dense concentration of gas and dust where infant stars form. This region is called Cepheus C because it lies in the constellation Cepheus, which can be found near the constellation Cassiopeia. Cepheus-C is about 6 light-years long, and lies about 40 light-years from the bright spot at the tip of the nebula.

The small, red hourglass shape just below Cepheus C is V374 Ceph. Astronomers studying this massive star have speculated that it might be surrounded by a nearly edge-on disk of dark, dusty material. The dark cones extending to the right and left of the star are a shadow of that disk.

The smaller nebula on the right side of the image includes a blue star crowned by a small, red arc of light. This "runaway star" is plowing through the gas and dust at a rapid clip, creating a shock wave or "bow shock" in front of itself.

Some features identified in the annotated image are more visible in the IRAC data alone.

The Jet Propulsion Laboratory in Pasadena, California, manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate in Washington. Science operations are conducted at the Spitzer Science Center at Caltech in Pasadena. Space operations are based at Lockheed Martin Space Systems in Littleton, Colorado. Data are archived at the Infrared Science Archive housed at IPAC at Caltech. Caltech manages JPL for NASA.

Source: JPL-Caltech/Spitzer

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A Field of Galaxies Seen by Spitzer and Hubble

This deep-field view of the sky, taken by NASA's Spitzer Space Telescope, is dominated by galaxies - including some very faint, very distant ones - circled in red. The bottom right inset shows one of those distant galaxies, made visible thanks to a long-duration observation by Spitzer. The wide-field view also includes data from NASA's Hubble Space Telescope. The Spitzer observations came from the GREATS survey, short for GOODS Re-ionization Era wide-Area Treasury from Spitzer. GOODS is itself an acronym: Great Observatories Origins Deep Survey. NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology, also in Pasadena. Caltech manages JPL for NASA. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. The Space Telescope Science Institute conducts Hubble science operations. The institute is operated for NASA by the Association of Universities for Research in Astronomy, Inc., Washington, D.C.  Credit NASA/JPL-Caltech/ESA/Spitzer/P. Oesch/S. De Barros/ I.Labbe 

This artist's illustration shows what one of the very first galaxies in the universe might have looked like. High levels of violent star formation and star death would have illuminated the gas filling the space between stars, making the galaxy largely opaque and without a clear structure. Credit: James Josephides (Swinburne Astronomy Productions)

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NASA's Spitzer Space Telescope has revealed that some of the universe's earliest galaxies were brighter than expected. The excess light is a byproduct of the galaxies releasing incredibly high amounts of ionizing radiation. The finding offers clues to the cause of the Epoch of Reionization, a major cosmic event that transformed the universe from being mostly opaque to the brilliant starscape seen today.

In a new study, researchers report on observations of some of the first galaxies to form in the universe, less than 1 billion years after the big bang (or a little more than 13 billion years ago). The data show that in a few specific wavelengths of infrared light, the galaxies are considerably brighter than scientists anticipated. The study is the first to confirm this phenomenon for a large sampling of galaxies from this period, showing that these were not special cases of excessive brightness, but that even average galaxies present at that time were much brighter in these wavelengths than galaxies we see today.

No one knows for sure when the first stars in our universe burst to life. But evidence suggests that between about 100 million and 200 million years after the big bang, the universe was filled mostly with neutral hydrogen gas that had perhaps just begun to coalesce into stars, which then began to form the first galaxies. By about 1 billion years after the big bang, the universe had become a sparkling firmament. Something else had changed, too: Electrons of the omnipresent neutral hydrogen gas had been stripped away in a process known as ionization. The Epoch of Reionization - the changeover from a universe full of neutral hydrogen to one filled with ionized hydrogen - is well documented.

Before this universe-wide transformation, long-wavelength forms of light, such as radio waves and visible light, traversed the universe more or less unencumbered. But shorter wavelengths of light - including ultraviolet light, X-rays and gamma rays - were stopped short by neutral hydrogen atoms. These collisions would strip the neutral hydrogen atoms of their electrons, ionizing them.

But what could have possibly produced enough ionizing radiation to affect all the hydrogen in the universe? Was it individual stars? Giant galaxies? If either were the culprit, those early cosmic colonizers would have been different than most modern stars and galaxies, which typically don't release high amounts of ionizing radiation. Then again, perhaps something else entirely caused the event, such as quasars - galaxies with incredibly bright centers powered by huge amounts of material orbiting supermassive black holes.

"It's one of the biggest open questions in observational cosmology," said Stephane De Barros, lead author of the study and a postdoctoral researcher at the University of Geneva in Switzerland. "We know it happened, but what caused it? These new findings could be a big clue."

Looking for Light

To peer back in time to the era just before the Epoch of Reionization ended, Spitzer stared at two regions of the sky for more than 200 hours each, allowing the space telescope to collect light that had traveled for more than 13 billion years to reach us.

As some of the longest science observations ever carried out by Spitzer, they were part of an observing campaign called GREATS, short for GOODS Re-ionization Era wide-Area Treasury from Spitzer. GOODS (itself an acronym: Great Observatories Origins Deep Survey) is another campaign that performed the first observations of some GREATS targets. The study, published in the Monthly Notices of the Royal Astronomical Society, also used archival data from NASA's Hubble Space Telescope.

Using these ultra-deep observations by Spitzer, the team of astronomers observed 135 distant galaxies and found that they were all particularly bright in two specific wavelengths of infrared light produced by ionizing radiation interacting with hydrogen and oxygen gases within the galaxies. This implies that these galaxies were dominated by young, massive stars composed mostly of hydrogen and helium. They contain very small amounts of "heavy" elements (like nitrogen, carbon and oxygen) compared to stars found in average modern galaxies.

These stars were not the first stars to form in the universe (those would have been composed of hydrogen and helium only) but were still members of a very early generation of stars. The Epoch of Reionization wasn't an instantaneous event, so while the new results are not enough to close the book on this cosmic event, they do provide new details about how the universe evolved at this time and how the transition played out.

"We did not expect that Spitzer, with a mirror no larger than a Hula-Hoop, would be capable of seeing galaxies so close to the dawn of time," said Michael Werner, Spitzer's project scientist at NASA's Jet Propulsion Laboratory in Pasadena, California. "But nature is full of surprises, and the unexpected brightness of these early galaxies, together with Spitzer's superb performance, puts them within range of our small but powerful observatory."

NASA's James Webb Space Telescope, set to launch in 2021, will study the universe in many of the same wavelengths observed by Spitzer. But where Spitzer's primary mirror is only 85 centimeters (33.4 inches) in diameter, Webb's is 6.5 meters (21 feet) - about 7.5 times larger - enabling Webb to study these galaxies in far greater detail. In fact, Webb will try to detect light from the first stars and galaxies in the universe. The new study shows that due to their brightness in those infrared wavelengths, the galaxies observed by Spitzer will be easier for Webb to study than previously thought.

"These results by Spitzer are certainly another step in solving the mystery of cosmic reionization," said Pascal Oesch, an assistant professor at the University of Geneva and a co-author on the study. "We now know that the physical conditions in these early galaxies were very different than in typical galaxies today. It will be the job of the James Webb Space Telescope to work out the detailed reasons why."

JPL manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate in Washington. Science operations are conducted at the Spitzer Science Center at Caltech in Pasadena. Space operations are based at Lockheed Martin Space Systems in Littleton, Colorado. Data are archived at the Infrared Science Archive housed at IPAC at Caltech. Caltech manages JPL for NASA.

News Media Contact

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

Source: JPL-Caltech/Spitzer/News

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Newborn Stars Blow Bubbles in the Cat's Paw Nebula

The Cat's Paw Nebula, imaged here by NASA's Spitzer Space Telescope using the MIPS and IRAC instruments, is a star-forming region that lies inside the Milky Way Galaxy. New stars may heat up the surrounding gas, which can expand to form "bubbles."  Credit: NASA/JPL-Caltech

The Cat's Paw Nebula, imaged here by NASA's Spitzer Space Telescope using the IRAC instrument, is a star-forming region inside the Milky Way Galaxy. The dark filament running through the middle of the nebula is a particularly dense region of gas and dust. Credit: NASA/JPL-Caltech

This image from NASA's Spitzer Space Telescope shows the Cat's Paw Nebula, so named for the large, round features that create the impression of a feline footprint. The nebula is a star-forming region in the Milky Way galaxy, located in the constellation Scorpius. Estimates of its distance from Earth range from about 4,200 to about 5,500 light-years.

Framed by green clouds, the bright red bubbles are the dominant feature in the image, which was created using data from two of Spitzer's instruments. After gas and dust inside the nebula collapse to form stars, the stars may in turn heat up the pressurized gas surrounding them, causing it to expand into space and create bubbles.

The green areas show places where radiation from hot stars collided with large molecules called "polycyclic aromatic hydrocarbons," causing them to fluoresce.

In some cases, the bubbles may eventually "burst," creating the U-shaped features that are particularly visible in the image below, which was created using data from just one of Spitzer's instruments.

Spitzer is an infrared telescope, and infrared light is useful to astronomers because it can penetrate thick clouds of gas and dust better than optical light (the kind visible to the human eye). The black filaments running horizontally through the nebula are regions of gas and dust so dense, not even infrared light can pass through them. These dense regions may soon be sites where another generation of stars will form.

The Cat's Paw star-forming region is estimated to be between 24 and 27 parsecs (80 and 90 light years) across. It extends beyond the left side of these images and intersects with a similar-sized star-forming region, NGC 6357. That region is also known as the Lobster Nebula - an unlikely companion for a cat.

The top image was compiled using data from the Infrared Array Camera (IRAC) and the Multiband Imaging Photometer (MIPS) aboard Spitzer. MIPS collects an additional "color" of light in the infrared range, which reveals the red-colored features, created by dust that has been warmed by the hot gas and the light from nearby stars. The second image is based on data from IRAC alone, so this dust is not visible.

The images were pulled from data collected for the Galactic Legacy Mid-Plane Survey Extraordinaire project (GLIMPSE). Using data from Spitzer, GLIMPSE created the most accurate map ever of the large central bar of the galaxy and showed that the galaxy is riddled with gas bubbles like those seen here.

News Media Contact

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

Source: JPL-Caltech,/Spitzer/News

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The Fading Ghost of a Long-Dead Star

HBH 3

Credit: NASA/JPL-Caltech/IPAC

Thin, red veins of energized gas mark the location of one of the larger supernova remnants in the Milky Way galaxy in this image from NASA's Spitzer Space Telescope.

A supernova "remnant" refers to the collective, leftover signs of an exploded star, or supernova. The red filaments in this image belong to a supernova remnant known as HBH 3 that was first observed in 1966 using radio telescopes. Traces of the remnant also radiate optical light. The branches of glowing material are most likely molecular gas that was pummeled by a shockwave generated by the supernova. The energy from the explosion energized the molecules and caused them to radiate infrared light.

The white, cloud-like formation also visible in the image is part of a complex of star-forming regions, simply named W3, W4 and W5. However, those regions extend far beyond the edge of this image. Both the white star-forming regions and the red filaments are approximately 6,400 light years away and lie inside our Milky Way galaxy.

HBH 3 is about 150 light-years in diameter, ranking it amongst the largest known supernova remnants. It is also possibly one of the oldest: Astronomers estimate the original explosion may have happened anywhere from 80,000 to one million years ago.

In 2016, NASA's Fermi Gamma-Ray Telescope detected very high-energy light -- called gamma rays -- coming from the region near HBH 3. This emission may be coming from gas in one of the neighboring star-forming regions, excited by powerful particles emitted by the supernova blast.

The Spitzer Space Telescope is one of NASA's four Great Observatories -- along with the Hubble Space Telescope, the Chandra X-ray Observatory and the Compton Gamma-Ray Observatory -- and will celebrate its 15th birthday in space on Aug. 25. Spitzer sees the universe in infrared light, which is slightly less energetic than the optical light we can see with our eyes. In this image, taken in March 2010, infrared wavelengths of 3.6 microns have been mapped to blue, and 4.5 microns to red. The white color of the star-forming region is a combination of both wavelengths, while the HBH3 filaments radiate only at the longer 4.5-micron wavelength.

JPL manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at Caltech in Pasadena, California. Spacecraft operations are based at Lockheed Martin Space Systems, Littleton, Colorado. Data are archived at the Infrared Science Archive housed at IPAC at Caltech. Caltech manages JPL for NASA.

News Media Contact

Calla Cofield
Jet Propulsion Laboratory, Pasadena, Calif.
818-393-1821
Calla.e.cofield@jpl.nasa.gov

Source: JPL-Caltech/Spitzer Space Telescope

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Gravitational Microlens Detection from Spitzer

Hubble Space Telescope images of a microlens system. The image on the left was taken 3.7 years after an observed microlensing event; the one on the right was taken 8.9 years later after the moving foreground (lensing) source had changed position. The lens and source components (A and B) are clearly resolved in the later image. Credit: NASA/Hubble

The path of light from a star as it passes by a massive body, like an exoplanet, will be bent and an observer looking towards the star will see its image distorted. Like an object seen through the stem of a wineglass, the stellar image could even be deformed into two bright peaks. That mass could influence light in this way was first confirmed in 1919, but some of the more subtle effects have only been detected in the past twenty-five years. In one such process, microlensing, a flash of light is produced when the path of a moving cosmic body (perhaps otherwise unknown) passes fortuitously in front of a star and briefly increases the intensity of its light. 

The Spitzer Space Telescope circles the Sun in an Earth-trailing orbit, and it is currently 1.66 astronomical units away from Earth (one AU is the average distance of the Earth form the Sun). Scientists had predicted that if it ever became possible to observe a microlensing flash from two well-separated vantage points, a parallax measurement (the apparent angular difference between the positions of the star as seen from the two separated sites) would determine the distance of the dark object. In fact, since 2014 Spitzer has been used successfully to measure the parallax for hundreds of microlensing events. In all these cases, Spitzer was used after ground-based observations had first identified a microlensing event underway.

CfA astronomers Jennifer Yee, Y. Jung, and In-Gu Shin were members of a collaboration that used Spitzer to record the first microlensing event in which only Spitzer (but not the ground-based sites) saw a double flash. Although this was in principle always possible, the effect had never before been observed, and proves that some double-peaked signals can be missed by ground-only observations. The result increases the importance of Spitzer observations beyond simply measuring parallax to include observing multiple-peak images and thus enabling a more precise characterization of the lens, which in the current instance is a binary system with a low-mass star and an orbiting companion.

Reference(s):

"OGLE-2017-BLG-1130: The First Binary Gravitational Microlens Detected from Spitzer Only," Tianshu Wang et al. ApJ 860, 25 (2018).

Source: Smithsonian Astrophysical Observatory (SAO)

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Giant Exoplanet Hunters: Look for Debris Disks

This artist's rendering shows a giant exoplanet causing small bodies to collide in a disk of dust. A study in The Astronomical Journal finds that giant exoplanets with long-period orbits are more likely to be found around young stars that have a disk of dust and debris than those without disks. The study focused on planets more than five times the mass of Jupiter. The astronomers are conducting the largest survey to date of stars with dusty debris disks, and finding the best evidence yet that giant planets are responsible for keeping that material in check.  Credit NASA/JPL-Caltech/T. Pyle (IPAC)

There's no map showing all the billions of exoplanets hiding in our galaxy -- they're so distant and faint compared to their stars, it's hard to find them. Now, astronomers hunting for new worlds have established a possible signpost for giant exoplanets.

A new study finds that giant exoplanets that orbit far from their stars are more likely to be found around young stars that have a disk of dust and debris than those without disks. The study, published in The Astronomical Journal, focused on planets more than five times the mass of Jupiter. This study is the largest to date of stars with dusty debris disks, and has found the best evidence yet that giant planets are responsible for keeping that material in check.

"Our research is important for how future missions will plan which stars to observe," said Tiffany Meshkat, lead author and assistant research scientist at IPAC/Caltech in Pasadena, California. Meshkat worked on this study as a postdoctoral researcher at NASA's Jet Propulsion Laboratory in Pasadena. "Many planets that have been found through direct imaging have been in systems that had debris disks, and now we know the dust could be indicators of undiscovered worlds."

Astronomers found the likelihood of finding long-period giant planets is nine times greater for stars with debris disks than stars without disks. Caltech graduate student Marta Bryan performed the statistical analysis that determined this result.

Researchers combined data from 130 single-star systems with debris disks detected by NASA's Spitzer Space Telescope, and compared them with 277 stars that do not appear to host disks. The two star groups were between a few million and 1 billion years old. Of the 130 stars, 100 were previously scanned for exoplanets. As part of this study, researchers followed up on the other 30 using the W. M. Keck Observatory in Hawaii and the European Southern Observatory's Very Large Telescope in Chile. They did not detect any new planets in those 30 systems, but the additional data helped characterize the abundance of planets in systems with disks.

The research does not directly resolve why the giant exoplanets would cause debris disks to form. Study authors suggest the massive gravity of giant planets causes small bodies called planetesimals to collide violently, rather than form proper planets, and remain in orbit as part of a disk.

"It's possible we don't find small planets in these systems because, early on, these massive bodies destroyed the building blocks of rocky planets, sending them smashing into each other at high speeds instead of gently combining," said co-author Dimitri Mawet, a Caltech associate professor of astronomy and a JPL senior research scientist.

On the other hand, giant exoplanets are easier to detect than rocky planets, and it is possible that there are some in these systems that have not yet been found.

Our own solar system is home to gas giants responsible for making "debris belts" -- the asteroid belt between Mars and Jupiter, shaped by Jupiter, and the Kuiper Belt, shaped by Neptune. Many of the systems Meshkat and Mawet studied also have two belts, but they are also much younger than ours -- up to 1 billion years old, compared to our system's present age of 4.5 billion years. The youth of these systems partly explains why they contain much more dust -- resulting from the collisions of small bodies -- than ours does.

One system discussed in the study is Beta Pictoris, which has been directly imaged from ground-based telescopes. This system has a debris disk, comets and one confirmed exoplanet. In fact, scientists predicted this planet's existence well before it was confirmed, based on the presence and structure of the prominent disk.

In a different scenario, the presence of two dust belts in a single debris disk suggests there are likely more planets in the system whose gravity maintains these belts, as is the case in the HR8799 system of four giant planets. The gravitational forces of giant planets nudge passing comets inward toward the star, which could mimic the period of our solar system's history about 4 billion years ago known as the Late Heavy Bombardment. Scientists think that during that period, the migration of Jupiter, Saturn, Uranus and Neptune deflected dust and small bodies into the Kuiper and asteroid belts we see today. When the Sun was young, there would have been a lot more dust in our solar system as well.

"By showing astronomers where future missions such as NASA's James Webb Space Telescope have their best chance to find giant exoplanets, this research paves the way to future discoveries," said Karl Stapelfeldt of JPL, chief scientist of NASA's Exoplanet Exploration Program Office and study co-author.

For more information about exoplanets, visit: https://exoplanets.nasa.gov


Elizabeth Landau
Jet Propulsion Laboratory, Pasadena, CA
818-354-6425
elizabeth.landau@jpl.nasa.gov

Source: JPL-Caltech/News