A Dusty Disk Points to a Potential Planet

Hubble Space Telescope observations of the Beta Pictoris debris disk, which led to a planet discovery.
Credit: NASA, ESA, and D. Apai and G. Schneider (University of Arizona)

JWST observations of a nearby star’s debris disk recently revealed what may be one of the lowest-mass planets ever imaged.

How to Find a Small Planet

Though it remains a formidable technical challenge, astronomers have gotten fairly good at taking images of planets around other stars by carefully blocking the light of the host and searching for the small points of light that remain. However, though this technique is well-suited for discovering large, bright, high-mass planets, their lower-mass cousins below the size of Jupiter remain challenging to detect. To get pictures of these smaller worlds, astronomers must resort to detective work and search for signs of their presence through indirect means.

One promising approach is to look not for the planet itself, but rather its effect on the dusty disk of material around the star. These structures, called debris disks, are constantly replenished by planetesimals colliding and grinding one another to dust. If a planet happens to orbit within this disk, it will “stir” the dust into distinctive patterns including rings and spiral arms. If astronomers observe that a star has a debris disk with gaps or spirals, they can analyze those substructures and deduce where a planet might be hiding.

A mid-infrared image of TWA 7’s debris disk and candidate planet.
Credit: ESA/Webb, NASA, CSA, A.M. Lagrange, M. Zamani (ESA/Webb); CC BY 4.0

The Star of this Show: TWA 7

TWA 7 is a tiny M-dwarf star just over 100 light-years from Earth. Data from the Spitzer Space Telescope revealed that TWA 7 was unusually bright when observed at infrared wavelengths, which hinted that there might be a warm, dusty disk surrounding the star. Follow-up observations with the Hubble Space Telescope and several major ground-based facilities confirmed that this star successfully met all the conditions listed above: TWA 7 is surrounded by a face-on debris disk with rings and a faint spiral arm. Using all of this information, astronomers predicted that a Saturn-mass planet might lie in a low-density pocket of the disk just beside the star.

This prediction led to a search with JWST last summer. Initial observations taken at mid-infrared wavelengths revealed a bright dot sitting near the predicted location of the planet. However, with just these observations, it was hard to confidently say that this source wasn’t just a distant background galaxy that happened to appear there by chance. To help settle the matter, JWST took another look in two different near-infrared wavelength bands a few weeks later.

New JWST observations of TWA 7. The sources labeled C5 and C6 are planet candidates. C6 is located at the same place as the planet candidate identified in mid-infrared observations, making it a strong candidate. C5 requires further observations to understand if it is real or an artifact. Credit: Crotts et al. 2025

Revisiting TWA 7

A team led by Katie Crotts (Space Telescope Science Institute) recently published these later observations. These new data show a dot in the exact same place as before, and with a color that’s much more planet-like than galaxy-like.

While this adds plenty of evidence to the planetary interpretation, the team cautions that one more set of follow-up observations is needed to be confident that this is, in fact, a planet. Assuming future observations back up these first hints, however, this would be the lowest-mass planet ever imaged, and a happy conclusion to a detective story that started with dust.

By Ben Cassese

Citation

“Follow-Up Exploration of the TWA 7 Planet–Disk System with JWST NIRCam,” Katie Crotts et al 2025 ApJL 987 L41.
doi:10.3847/2041-8213/ade798

Source: American Astronomical Society/AAS-Nova

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NASA's Webb Discovers Dusty 'Cat's Tail' in Beta Pictoris System

Beta Pictoris (MIRI Image)

Credits: Image: NASA, ESA, CSA, STScI, Christopher Stark (NASA-GSFC), Kellen Lawson (NASA-GSFC), Jens Kammerer (ESO), Marshall Perrin (STScI)

Beta Pictoris (MIRI Annotated Image)

Credits: Image: NASA, ESA, CSA, STScI, Christopher Stark (NASA-GSFC), Kellen Lawson (NASA-GSFC), Jens Kammerer (ESO), Marshall Perrin (STScI)

Release ImagesRelease Videos

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Beta Pictoris, a young planetary system located just 63 light-years away, continues to intrigue scientists even after decades of in-depth study. It possesses the first dust disk imaged around another star — a disk of debris produced by collisions between asteroids, comets, and planetesimals. Observations from NASA’s Hubble Space Telescope revealed a second debris disk in this system, inclined with respect to the outer disk, which was seen first. Now, a team of astronomers using NASA’s James Webb Space Telescope to image the Beta Pictoris (Beta Pic) system has discovered a new, previously unseen structure.

The team, led by Isabel Rebollido of the Astrobiology Center in Spain, used Webb’s NIRCam (Near-Infrared Camera) and MIRI (Mid-Infrared Instrument) to investigate the composition of Beta Pic’s previously detected main and secondary debris disks. The results exceeded their expectations, revealing a sharply inclined branch of dust, shaped like a cat’s tail, that extends from the southwest portion of the secondary debris disk.

“Beta Pictoris is the debris disk that has it all: It has a really bright, close star that we can study very well, and a complex cirumstellar environment with a multi-component disk, exocomets, and two imaged exoplanets,” said Rebollido, lead author of the study. “While there have been previous observations from the ground in this wavelength range, they did not have the sensitivity and the spatial resolution that we now have with Webb, so they didn’t detect this feature.”

A Star’s Portrait Improved with Webb

Even with Webb, or JWST, peering at Beta Pic in the right wavelength range — in this case, the mid-infrared — was crucial to detect the cat’s tail, as it only appeared in the MIRI data. Webb’s mid-infrared data also revealed differences in temperature between Beta Pic’s two disks, which likely is due to differences in composition.

“We didn’t expect Webb to reveal that there are two different types of material around Beta Pic, but MIRI clearly showed us that the material of the secondary disk and cat’s tail is hotter than the main disk,” said Christopher Stark, a co-author of the study at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “The dust that forms that disk and tail must be very dark, so we don’t easily see it at visible wavelengths — but in the mid-infrared, it’s glowing.”

To explain the hotter temperature, the team deduced that the dust may be highly porous “organic refractory material,” similar to the matter found on the surfaces of comets and asteroids in our solar system. For example, a preliminary analysis of material sampled from asteroid Bennu by NASA’s OSIRIS-REx mission found it to be very dark and carbon-rich, much like what MIRI detected at Beta Pic.

The Tail’s Puzzling Beginning Warrants Future Research

However, a major lingering question remains: What could explain the shape of the cat’s tail, a uniquely curved feature unlike what is seen in disks around other stars?

Rebollido and the team modeled various scenarios in an attempt to emulate the cat’s tail and unravel its origins. Though further research and testing is required, the team presents a strong hypothesis that the cat’s tail is the result of a dust production event that occurred a mere one hundred years ago.

“Something happens — like a collision — and a lot of dust is produced,” shared Marshall Perrin, a co-author of the study at the Space Telescope Science Institute in Baltimore, Maryland. “At first, the dust goes in the same orbital direction as its source, but then it also starts to spread out. The light from the star pushes the smallest, fluffiest dust particles away from the star faster, while the bigger grains do not move as much, creating a long tendril of dust.”

“The cat’s tail feature is highly unusual, and reproducing the curvature with a dynamical model was difficult,” explained Stark. “Our model requires dust that can be pushed out of the system extremely rapidly, which again suggests it’s made of organic refractory material.”

The team’s preferred model explains the sharp angle of the tail away from the disk as a simple optical illusion. Our perspective combined with the curved shape of the tail creates the observed angle of the tail, while in fact, the arc of material is only departing from the disk at a five-degree incline. Taking into consideration the tail’s brightness, the team estimates the amount of dust within the cat’s tail to be equivalent to a large main belt asteroid spread out across 10 billion miles.

A recent dust production event within Beta Pic’s debris disks could also explain a newly-seen asymmetric extension of the inclined inner disk, as shown in the MIRI data and seen only on the side opposite of the tail. Recent collisional dust production could also account for a feature previously spotted by the Atacama Large Millimeter/submillimeter Array in 2014 : a clump of carbon monoxide (CO) located near the cat’s tail. Since the star’s radiation should break down CO within roughly one hundred years, this still-present concentration of gas could be lingering evidence of the same event.

“Our research suggests that Beta Pic may be even more active and chaotic than we had previously thought,” said Stark. “JWST continues to surprise us, even when looking at the most well-studied objects. We have a completely new window into these planetary systems.”

These results were presented in a press conference at the 243rd meeting of the American Astronomical Society in New Orleans, Louisiana.

The observations were taken as part of Guaranteed Time Observation program 1411 .

The James Webb Space Telescope is the world’s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and the Canadian Space Agency.

Source: NASA's James Webb Space Telescope/News

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Abigail Major
Space Telescope Science Institute, Baltimore, Maryland

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Space Telescope Science Institute, Baltimore, Maryland

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NASA’s Webb to Explore a Neighboring, Dusty Planetary System

A debris disk, which includes comets, asteroids, rocks of various sizes, and plenty of dust, orbits the star Beta Pictoris, which is blocked at the center of this 2012 image by a coronagraph aboard the Hubble Space Telescope. This is the visible-light view of the system. NASA’s James Webb Space Telescope will view Beta Pictoris in infrared light, both using its coronagraphs and capturing data known as spectra to allow researchers to learn significantly more about the gas and dust in the debris disk, which includes lots of smaller bodies like exocomets. Credits: IMAGE: NASA, ESA, Daniel Apai (University of Arizona), Glenn Schneider (University of Arizona). Release Images

Researchers will take stock of the dust in the debris disk surrounding the nearby star Beta Pictoris

Planetary systems are very busy places. In addition to the planets orbiting their host star, planetary systems are chock full of dust and other fragments left over from planet formation – a debris disk. Our own solar system includes the Kuiper Belt, which begins beyond Neptune. Younger systems, though, are a bit less “organized.” Take Beta Pictoris, a planetary system only 63 light-years away with a mature star, at least two planets, and the first comets discovered outside our solar system. Although researchers have observed it with powerful space- and ground-based telescopes since the 1980s, there’s still a lot we don’t yet know about its overall makeup. That’s why researchers will study the dusty disk of Beta Pictoris with Webb to better map out its dusty contents.

Researchers will use NASA’s upcoming James Webb Space Telescope to study Beta Pictoris, an intriguing young planetary system that sports at least two planets, a jumble of smaller, rocky bodies, and a dusty disk. Their goals include gaining a better understanding of the structures and properties of the dust to better interpret what is happening in the system. Since it’s only about 63 light-years away and chock full of dust, it appears bright in infrared light – and that means there is a lot of information for Webb to gather.

Beta Pictoris is the target of several planned Webb observing programs, including one led by Chris Stark of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and two led by Christine Chen of the Space Telescope Science Institute (STScI) in Baltimore, Maryland. Stark’s program will directly image the system after blocking the light of the star to gather a slew of new details about its dust. Chen’s programs will gather spectra, which spread light out like a rainbow to reveal which elements are present. All three observing programs will add critical details to what’s known about this nearby system.

First, a Review of What We Know

Beta Pictoris has been regularly studied in radio, infrared, and visible light since the 1980s. The star itself is twice as massive as our sun and quite a bit hotter, but also significantly younger. (The Sun is 4.6 billion years old, but Beta Pictoris is approximately 20 million years old.) At this stage, the star is stable and hosts at least two planets, which are both far more massive than Jupiter. But this planetary system is remarkable because it is where the first exocomets (comets in other systems) were discovered. There are quite a lot of bodies zipping around this system!

Like our own solar system, Beta Pictoris has a debris disk, which includes comets, asteroids, rocks of various sizes, and plenty of dust in all shapes that orbit the star. (A debris disk is far younger and can be more massive than our solar system’s Kuiper Belt, which begins near Neptune’s orbit and is where many short-period comets originate.)

This outside ring of dust and debris is also where a lot of activity is happening. Pebbles and boulders could be colliding and breaking into far smaller pieces — sending out plenty of dust.

Scrutinizing This Planetary System

Stark’s team will use Webb’s coronagraphs, which block the light of the star, to observe the faint portions of the debris disk that surround the entire system. “We know there are two massive planets around Beta Pictoris, and farther out there is a belt of small bodies that are colliding and fragmenting,” Stark explained. “But what’s in between? How similar is this system to our solar system? Can dust and water ice from the outer belt eventually make its way into the inner region of the system? Those are details we can help tease out with Webb.”

Webb’s imagery will allow the researchers to study how the small dust grains interact with planets that are present in that system. Plus, Webb will detail all the fine dust that streams off these objects, permitting the researchers to infer the presence of larger rocky bodies and what their distribution is in the system. They’ll also carefully assess how the dust scatters light and reabsorbs and reemits light when it’s warm, allowing them to constrain what the dust is made of. By cataloging the specifics of Beta Pictoris, the researchers will also assess how similar this system is to our solar system, helping us understand if the contents of our solar system are unique.

Isabel Rebollido, a team member and postdoctoral researcher at STScI, is already building complex models of Beta Pictoris. The first model combines existing data about the system, including radio, near-infrared, far-infrared, and visible light from both space- and ground-based observatories. In time, she will add Webb’s imagery to run a fuller analysis.

The second model will feature only Webb’s data – and will be the first they explore. “Is the light Webb will observe symmetrical?” Rebollido asked. “Or are there ‘bumps’ of light here and there because there is an accumulation of dust? Webb is far more sensitive than any other space telescope and gives us a chance to look for this evidence, as well as water vapor where we know there’s gas.”

Dust as a Decoder Ring

Think of the debris disk of Beta Pictoris as a very busy, elliptical highway – except one where there aren’t many traffic rules. Collisions between comets and larger rocks can produce fine dust particles that subsequently scatter throughout the system.

“After planets, most of the mass in the Beta Pictoris system is thought to be in smaller planetesimals that we can’t directly observe,” Chen explained. “Fortunately, we can observe the dust left behind when planetesimals collide.”

This dust is where Chen’s team will focus its research. What do the smallest dust grains look like? Are they compact or fluffy? What are they made of?

“We’ll analyze Webb’s spectra to map the locations of dust and gas – and figure out what their detailed compositions are,” Chen explained. “Dust grains are ‘fingerprints’ of planetesimals we can’t see directly and can tell us about what these planetesimals are made of and how they formed.” For example, are the planetesimals ice-rich like comets in our solar system? Are there signs of high-speed collisions between rocky planetesimals? Clearly analyzing if grains in one region are more solid or fluffy than another will help the researchers understand what is happening to the dust, and map out the subtle differences in the dust in each region.

“I’m looking forward to analyzing Webb’s data since it will provide exquisite detail,” added Cicero X. Lu, a team member and a fourth-year Ph.D. student at Johns Hopkins University in Baltimore. “Webb will allow us to identify more elements and pinpoint their precise structures.”

In particular, there’s a cloud of carbon monoxide at the edge of the disk that greatly interests these researchers. It’s asymmetric and has an irregular, blobby side. One theory is that collisions released dust and gas from larger, icy bodies to form this cloud. Webb’s spectra will help them build scenarios that explain its origin.

The Reach of Infrared

These research programs are only possible because Webb has been designed to provide crisp, high-resolution detail in infrared light. The observatory specializes in collecting infrared light – which travels through gas and dust – both with images and spectra. Webb also has another advantage – its position in space. Webb will not be hindered by Earth’s atmosphere, which filters out some types of light, including several infrared wavelength bands. This observatory will allow researchers to gather a more complete range of infrared light and data about Beta Pictoris for the first time.

These studies will be conducted as part of Webb Guaranteed Time Observations (GTO) and General Observers (GO) programs. The GTO programs are led by scientists who helped develop the key hardware and software components or technical and inter-disciplinary knowledge for the observatory. GO programs are competitively selected using a dual-anonymous review system, the same system that is used to allocate time on the Hubble Space Telescope.

The James Webb Space Telescope will be the world's premier space science observatory when it launches in 2021. Webb will solve mysteries in our solar system, look beyond to distant worlds around other stars, and probe the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and the Canadian Space Agency.

 

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Claire Blome
Space Telescope Science Institute, Baltimore, Maryland

Christine Pulliam
Space Telescope Science Institute, Baltimore, Maryland

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Direct inquiries to the News Team.

Related Links and Documents:

Visualization of a Debris Disk: "How Planets Form"

Source: NASA's James Webb Space Telescope/News

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Hubble Gets Best View of a Circumstellar Debris Disk Distorted by a Planet Release Images

Hubble Views of Beta Pictoris (1997 and 2012)

Credit: NASA, ESA, and D. Apai and G. Schneider (University of Arizona)

 Release Images

Astronomers have used NASA's Hubble Space Telescope to take the most detailed picture to date of a large, edge-on, gas-and-dust disk encircling the 20-million-year-old star Beta Pictoris.

Beta Pictoris remains the only directly imaged debris disk that has a giant planet (discovered in 2009). Because the orbital period is comparatively short (estimated to be between 18 and 22 years), astronomers can see large motion in just a few years. This allows scientists to study how the Beta Pictoris disk is distorted by the presence of a massive planet embedded within the disk.

The new visible-light Hubble image traces the disk in closer to the star to within about 650 million miles of the star (which is inside the radius of Saturn's orbit about the Sun).

"Some computer simulations predicted a complicated structure for the inner disk due to the gravitational pull by the short-period giant planet. The new images reveal the inner disk and confirm the predicted structures. This finding validates models, which will help us to deduce the presence of other exoplanets in other disks," said Daniel Apai of the University of Arizona. The gas-giant planet in the Beta Pictoris system was directly imaged in infrared light by the European Southern Observatory's Very Large Telescope six years ago.

When comparing the latest Hubble images to Hubble images taken in 1997, astronomers find that the disk's dust distribution has barely changed over 15 years despite the fact that the entire structure is orbiting the star like a carousel. This means the disk's structure is smoothly continuous in the direction of its rotation on the timescale, roughly, of the accompanying planet's orbital period.

In 1984 Beta Pictoris was the very first star discovered to host a bright disk of light-scattering circumstellar dust and debris. Ever since then Beta Pictoris has been an object of intensive scrutiny with Hubble and with ground-based telescopes. Hubble spectroscopic observations in 1991 found evidence for extrasolar comets frequently falling into the star.

The disk is easily seen because it is tilted edge-on and is especially bright due to a very large amount of starlight-scattering dust. What's more, Beta Pictoris is closer to Earth (63 light-years) than most of the other known disk systems.

Though nearly all of the approximately two-dozen known light-scattering circumstellar disks have been viewed by Hubble to date, Beta Pictoris is the first and best example of what a young planetary system looks like, say researchers.

One thing astronomers have recently learned about circumstellar debris disks is that their structure, and amount of dust, is incredibly diverse and may be related to the locations and masses of planets in those systems. "The Beta Pictoris disk is the prototype for circumstellar debris systems, but it may not be a good archetype," said co-author Glenn Schneider of the University of Arizona.

For one thing the Beta Pictoris disk is exceptionally dusty. This may be due to recent major collisions among unseen planetary-sized and asteroid-sized bodies embedded within it. In particular, a bright lobe of dust and gas on the southwestern side of the disk may be the result of the pulverization of a Mars-sized body in a giant collision.

Both the 1997 and 2012 images were taken in visible light with Hubble's Space Telescope Imaging Spectrograph in its coronagraphic imaging mode. A coronagraph blocks out the glare of the central star so that the disk can be seen. 

Contact

Ray Villard
Space Telescope Science Institute, Baltimore, Md.
410-338-4514
villard@stsci.edu

Daniel Apai / Glenn Schneider
University of Arizona, Tucson, Ariz.
520-621-6534 / 520-621-5865
apai@arizona.edu / gschneider@as.arizona.edu

Source: HubbleSite

   

Crashing Comets Explain Surprise Gas Clump Around Young Star

PR Image eso1408a

Artist's impression of Beta Pictoris

PR Image eso1408b
Map of the sky around Beta Pictoris 

PR Image eso1408c

Around Beta Pictoris

PR Image eso1408d

ALMA image of carbon monoxide around Beta Pictoris (infographic)

ALMA reveals an enigmatic gas clump in debris disc around Beta Pictoris

Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) telescope in northern Chile have today announced the discovery of an unexpected clump of carbon monoxide gas in the dusty disc around the star Beta Pictoris. This is a surprise, as such gas is expected to be rapidly destroyed by starlight. Something — probably frequent collisions between small, icy objects such as comets — must be causing the gas to be continuously replenished. The new results are published today in the journal Science. 

Beta Pictoris, a nearby star easily visible to the naked eye in the southern sky, is already hailed as the archetypal young planetary system. It is known to harbour a planet that orbits some 1.2 billion kilometres from the star, and it was one of the first stars found to be surrounded by a large disc of dusty debris [1].

New observations from ALMA now show that the disc is permeated by carbon monoxide gas. Paradoxically the presence of carbon monoxide, which is so harmful to humans on Earth, could indicate that the Beta Pictoris planetary system may eventually become a good habitat for life. The cometary bombardment that its planets are currently undergoing is likely providing them with life-enabling water [2].

But carbon monoxide is easily and rapidly broken up by starlight — it can only last about 100 years where it is observed in the Beta Pictoris disc. Seeing it in the 20-million year old Beta Pictoris disc is a complete surprise. So where did it come from, and why is it still there?

“Unless we are observing Beta Pictoris at a very unusual time, the carbon monoxide must be continuously replenished,” said Bill Dent, an ESO astronomer at the Joint ALMA Office in Santiago, Chile, and lead author on a paper published today in the journal Science. “The most abundant source of carbon monoxide in a young solar system is collisions between icy bodies, from comets up to larger planet-sized objects.”

But the rate of destruction must be very high: “To get the amount of carbon monoxide we observe, the rate of collisions would be truly startling — one large comet collision every five minutes,” noted Aki Roberge, an astronomer at NASA’s Goddard Research Center in Greenbelt, USA, and coauthor of the paper. “To get this number of collisions, this would have to be a very tight, massive comet swarm.”

But there was another surprise in the ALMA observations, which did not just discover the carbon monoxide, but also mapped its location in the disc, through ALMA’s unique ability to simultaneously measure both position and velocity: the gas is concentrated in a single compact clump. This concentration lies 13 billion kilometres from the star, which is about three times the distance of Neptune from the Sun. Why the gas is in this small clump so far from the star is a mystery.

“This clump is an important clue to what is going on in the outer reaches of this young planetary system,” says Mark Wyatt, an astronomer at the University of Cambridge, UK, and a co-author on the paper. He goes on to explain that there are two ways such a clump can form: “Either the gravitational pull of an as yet unseen planet similar in mass to Saturn is concentrating the cometary collisions into a small area, or what we are seeing are the remnants of a single catastrophic collision between two icy Mars-mass planets”.

Both of these possibilities give astronomers reason to be optimistic that there are several more planets waiting to be found around Beta Pictoris. “Carbon monoxide is just the beginning — there may be other more complex pre-organic molecules released from these icy bodies,” adds Roberge.

Further observations are planned with ALMA, which is still ramping up to its full capabilities, to shed more light on this intriguing planetary system, and so help us to understand what conditions were like during the formation of the Solar System.

Notes

[1] Many stars are surrounded by swirling clouds of dust, known as debris discs.They are the remains of a collisional cascade of the rocks in orbit around the star, much like the collisional breakup of the space station depicted in the movie Gravity (but on a much larger scale). Earlier observations of Beta Pictoris were reported in eso1024 and eso0842.

[2] Comets contain ices of carbon monoxide, carbon dioxide, ammonia and methane, but the majority component is a mixture of dust and water ice.

More information

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Southern Observatory (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI) and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

This research was presented in a paper entitled “Molecular Gas Clumps from the Destruction of Icy Bodies in the β Pictoris Debris Disk” to appear in the journal Science on 6 March 2014.

The team is composed of W.R.F. Dent (Joint ALMA Office, Santiago, Chile [JAO]), M.C. Wyatt (Institute of Astronomy, Cambridge, UK [IoA]), A. Roberge (NASA Goddard Space Flight Center, Greenbank, USA), J.-C. Augereau (Institut de Planétologie et d'Astrophysique de Grenoble, France [IPAG]), S. Casassus (Universidad de Chile, Santiago, Chile), S. Corder (JAO), J.S. Greaves (University of St. Andrews, UK), I. de Gregorio-Monsalvo (JAO), A. Hales (JAO), A.P.Jackson (IoA), A. Meredith Hughes (Wesleyan University, Middletown, USA), A.-M. Lagrange (IPAG), B. Matthews (National Research Council of Canada, Victoria, Canada) and D. Wilner (Smithsonian Astrophysical Observatory, Cambridge, USA).

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning the 39-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

Links

• Science paper
• NRAO release
• NASA release
• ALMA pictures
• Further information about ALMA

Contacts

Bill Dent
Joint ALMA Office
Santiago, Chile
Email: wdent@alma.cl

Richard Hook
ESO, Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email: rhook@eso.org

Source: ESO

Beta Pictoris planet finally imaged?

ESO PR Photo 42b/08
Beta Pictoris as seen in infrared light - annotated

ESO PR Photo 42c/08

Candidate planetary systems imaged

This diagramme compares the various candidate planetary systems that have been imaged for now, with our Solar System. Indicated are the star and the position of the imaged candidate planets. The probable planet around Beta Pictoris is the closest to its host star of all extra-solar planets yet imaged, and is comparable to Saturn as far as its distance is concerned. The scale is the distance between the Earth and the Sun. A list of all candidate exoplanets directly imaged can be found at http://exoplanet.eu/catalog-imaging.php
Credit: ESO

A team of French astronomers using ESO's Very Large Telescope have discovered an object located very close to the star Beta Pictoris, and which apparently lies inside its disc. With a projected distance from the star of only 8 times the Earth-Sun distance, this object is most likely the giant planet suspected from the peculiar shape of the disc and the previously observed infall of comets onto the star. It would then be the first image of a planet that is as close to its host star as Saturn is to the Sun.

The hot star Beta Pictoris is one of the best-known examples of stars surrounded by a dusty 'debris' disc. Debris discs are composed of dust resulting from collisions among larger bodies like planetary embryos or asteroids. They are a bigger version of the zodiacal dust in our Solar System. Its disc was the first to be imaged — as early as 1984 — and remains the best-studied system. Earlier observations showed a warp of the disc, a secondary inclined disc and infalling comets onto the star. "These are indirect, but tell-tale signs that strongly suggest the presence of a massive planet lying between 5 and 10 times the mean Earth-Sun distance from its host star," says team leader Anne-Marie Lagrange. "However, probing the very inner region of the disc, so close to the glowing star, is a most challenging task."

In 2003, the French team used the NAOS-CONICA instrument (or NACO [1]), mounted on one of the 8.2 m Unit Telescopes of ESO's Very Large Telescope (VLT), to benefit from both the high image quality provided by the Adaptive Optics system at infrared wavelengths and the good dynamics offered by the detector, in order to study the immediate surroundings of Beta Pictoris.

Recently, a member of the team re-analysed the data in a different way to seek the trace of a companion to the star. Infrared wavelengths are indeed very well suited for such searches. "For this, the real challenge is to identify and subtract as accurately as possible the bright stellar halo," explains Lagrange. "We were able to achieve this after a precise and drastic selection of the best images recorded during our observations."

The strategy proved very rewarding, as the astronomers were able to discern a feeble, point-like glow well inside the star's halo. To eliminate the possibility that this was an artefact and not a real object, a battery of tests was conducted and several members of the team, using three different methods, did the analysis independently, always with the same success. Moreover, the companion was also discovered in other data sets, further strengthening the team's conclusion: the companion is real.

"Our observations point to the presence of a giant planet, about 8 times as massive as Jupiter and with a projected distance from its star of about 8 times the Earth-Sun distance, which is about the distance of Saturn in our Solar System [2]," says Lagrange.

"We cannot yet rule out definitively, however, that the candidate companion could be a foreground or background object," cautions co-worker Gael Chauvin. "To eliminate this very small possibility, we will need to make new observations that confirm the nature of the discovery."

The team also dug into the archives of the Hubble Space Telescope but couldn't see anything, "while most possible foreground or background objects would have been detected", remarks another team member, David Ehrenreich.

The fact that the candidate companion lies in the plane of the disc also strongly implies that it is bound to the star and its proto-planetary disc.

"Moreover, the candidate companion has exactly the mass and distance from its host star needed to explain all the disc's properties. This is clearly another nail in the coffin of the false alarm hypothesis," adds Lagrange.

When confirmed, this candidate companion will be the closest planet from its star ever imaged. In particular, it will be located well inside the orbits of the outer planets of the Solar System. Several other planetary candidates have indeed been imaged, but they are all located further away from their host star: if located in the Solar System, they would lie close or beyond the orbit of the farthest planet, Neptune. The formation processes of these distant planets are likely to be quite different from those in our Solar System and in Beta Pictoris.

"Direct imaging of extrasolar planets is necessary to test the various models of formation and evolution of planetary systems. But such observations are only beginning. Limited today to giant planets around young stars, they will in the future extend to the detection of cooler and older planets, with the forthcoming instruments on the VLT and on the next generation of optical telescopes," concludes team member Daniel Rouan.

Only 12 million years old, the 'baby star' Beta Pictoris is located about 70 light-years away towards the constellation Pictor (the Painter).

Notes

[1] NACO is one of the instruments on ESO's VLT that make use of Adaptive Optics (AO). Such systems work by means of a computer-controlled deformable mirror that counteracts the image distortion induced by atmospheric turbulence (see e.g. ESO Press Release 25/01).

[2] The astronomers can only see the projected separation between the star and the planet (that is, the separation projected on the plane of the sky).

More Information:
"A probable giant planet imaged in the β Pictoris disk. VLT/NACO Deep L-band imaging", by A.-M. Lagrange et al., 2008, Letter to the Editor of Astronomy and Astrophysics, in press. (a PDF file can be downloaded here)
The team is composed of A.-M. Lagrange, G. Chauvin, D. Ehrenreich, and D. Mouillet (Laboratoire d'Astrophysique de l'Observatoire de Grenoble, France), D. Gratadour, G. Rousset, D. Rouan and E. Gendron (LESIA, Observatoire de Paris, France), T. Fusco, and L. Mugnier (Office National d'Etudes et de Recherches Aérospatiales, Chatillon, France), F. Allard (Centre de Recherche Astronomique de Lyon, France), and the NAOS Consortium.

Contacts:

Anne-Marie Lagrange and Gael Chauvin
LAOG, Grenoble, France
E-mail: anne-marie.lagrange@obs.ujf-grenoble.fr, gael.chauvin@obs.ujf-grenoble.fr
Phone: +33 4 7651 4203, +33 4 7663 5803

Daniel Rouan
LESIA, Observatoire de Paris, France
E-mail: daniel.rouan@obspm.fr
Phone: +33 1 4507 7715

ESO Press Officer: Dr. Henri Boffin - +49 89 3200 6222 - hboffin@eso.org
ESO Press Officer in Chile: Valentina Rodriguez - +56 2 463 3123 - vrodrigu@eso.org

Astronomers Find Highly Elliptical Disk Around Young Star

Credit: NASA, ESA, and P. Kalas (University of California, Berkeley)

Astronomers Find Highly Elliptical Disk Around Young Star

This image taken by NASA's Hubble Space Telescope shows a lopsided debris disk around the young star HD 15115.

The disk, seen edge-on, is the dense blue line extending from the star to the upper right and lower left of the image. As seen from Earth, the edge-on disk resembles a needle sticking out from the star. The disk appears thicker and longer at upper right than at lower left, evidence of the disk's lopsided structure.

Astronomers think the disk's odd imbalanced look is caused by dust particles following a highly elliptical orbit around the star, which is slightly brighter than the Sun. The lopsidedness may have been caused by planets sweeping up debris in the disk or by the gravity of a nearby star.

Astronomers used an occulting mask on Hubble's Advanced Camera for Surveys to block out the bright starlight so they could see the dim disk. The occulting masks can be seen in the image as the dark circle in the center and the dark bar on the left. The star is behind the central mask.

HD 15115 is among nearly 30 stars that belong to the Beta Pictoris Moving Group. Moving groups are expanded clusters of stars believed to have a common birthplace and age, in this case about 12 million years, that are traveling together loosely through space. HD 15115 is 150 light-years from Earth.

Dusty disks are known to exist around at least 100 stars, but because of the difficulty in observing material close to the brightness of a star, less than a dozen have been studied closely.

Astronomers described the disk as one of the most peculiar debris disks that Hubble has ever imaged. They in fact made follow-up observations with the W.M. Keck Observatory in Hawaii to confirm the disk's presence.

Hubble's Advanced Camera for Surveys snapped the image on July 17, 2006.