New study brings a doubted exoplanet 'back from the dead'

Oct 25, 2012

A second look at data from NASA's Hubble Space Telescope is reanimating the claim that the nearby star Fomalhaut hosts a massive exoplanet. The study suggests that the planet, named Fomalhaut b, is a rare and possibly unique object that is completely shrouded by dust.

"Although our results seriously challenge the original discovery paper, they do so in a way that actually makes the object's interpretation much cleaner and leaves intact the core conclusion, that b is indeed a ," said Thayne Currie, an astronomer formerly at NASA's Goddard Space Flight Center in Greenbelt, Md., and now at the University of Toronto.

The discovery study reported that Fomalhaut b's brightness varied by about a factor of two and cited this as evidence that the planet was accreting gas. Follow-up studies then interpreted this variability as evidence that the object actually was a transient dust cloud instead.

In the new study, Currie and his team reanalyzed Hubble observations of the star from 2004 and 2006. They easily recovered the planet in observations taken at visible wavelengths near 600 and 800 nanometers, and made a new detection in violet light near 400 nanometers. In contrast to the earlier research, the team found that the planet remained at constant brightness.

The team attempted to detect Fomalhaut b in the infrared using the in Hawaii, but was unable to do so. The non-detections with Subaru and Spitzer imply that Fomalhaut b must have less than twice the mass of Jupiter.

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In 2008, Hubble astronomers announced the detection of a giant planet around the bright star Fomalhaut. Recent studies have questioned this conclusion. Now, a reanalysis of Hubble data has revived the "deceased" exoplanet as a dust-shrouded world with less than twice the mass of Jupiter. Credit: NASA's Goddard Space Flight Center

Another contentious issue has been the object's orbit. If Fomalhaut b is responsible for the ring's offset and sharp interior edge, then it must follow an orbit aligned with the ring and must now be moving at its slowest speed. The speed implied by the original study appeared to be too fast. Additionally, some researchers argued that Fomalhaut b follows a tilted orbit that passes through the ring plane.

Using the Hubble data, Currie's team established that Fomalhaut b is moving with a speed and direction consistent with the original idea that the planet's gravity is modifying the ring.

"What we've seen from our analysis is that the object's minimum distance from the disk has hardly changed at all in two years, which is a good sign that it's in a nice ring-sculpting orbit," explained Timothy Rodigas, a graduate student in the University of Arizona and a member of the team.

Currie's team also addressed studies that interpret Fomalhaut b as a compact dust cloud not gravitationally bound to a planet. Near Fomalhaut's ring, orbital dynamics would spread out or completely dissipate such a cloud in as little as 60,000 years. The dust grains experience additional forces, which operate on much faster timescales, as they interact with the star's light.

"Given what we know about the behavior of dust and the environment where the planet is located, we think that we're seeing a planetary object that is completely embedded in dust rather than a free-floating dust cloud," said team member John Debes, an astronomer at the Space Telescope Science Institute in Baltimore, Md.

A paper describing the findings has been accepted for publication in The Astrophysical Journal Letters.

Because astronomers detect Fomalhaut b by the light of surrounding dust and not by light or heat emitted by its atmosphere, it no longer ranks as a "directly imaged ." But because it's the right mass and in the right place to sculpt the ring, Currie's team thinks it should be considered a "planet identified from direct imaging."

Fomalhaut was targeted with Hubble most recently in May by another team. Those observations are currently under scientific analysis and are expected to be published soon.

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User comments : 11

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Allex
2.6 / 5 (5) Oct 25, 2012
Reported for spamming
Nydoc
4 / 5 (8) Oct 25, 2012
VendicarD, you're trolling too hard. Go get some sleep.
Bowler_4007
2.8 / 5 (9) Oct 25, 2012
These so called scientists don't know nothing about planets, stars, and gravity.
When somebody doesn't know nothing it means they do know something.

It's just like the Global Warming Scam, and these scientists are just in it to steal my money ...
Paranoid.
Bowler_4007
1.7 / 5 (6) Oct 26, 2012
Apart from VendicarD (because his post here has been pushed off his recent posts list) all the users that posted here have been down voted on by the one set of users amd none of these voting users have contributed anything to this articles thread this is poor sport.

This is an appeal to the moderators/administator(s) make voting on a post possible only if the user voting has posted in that thread, the tone of the thread shouldn't matter to users who aren't posting in the thread because they either have nothing to say or are too late to post because the option to do so was removed (to all users)
Sinister1811
1 / 5 (5) Oct 26, 2012
Reported for spamming


He was being sarcastic, I believe.
yyz
3.7 / 5 (3) Oct 26, 2012
A separate study, based on a reanalysis of Hubble data, also finds that Fomalhaut b is likely a dust-enshrouded planet, consistent with the study reported here: http://arxiv.org/abs/1210.6745
rubberman
3.1 / 5 (7) Oct 26, 2012
I like the Simpsonesque animation.
rubberman
1 / 5 (5) Oct 26, 2012
Apart from VendicarD (because his post here has been pushed off his recent posts list) all the users that posted here have been down voted on by the one set of users amd none of these voting users have contributed anything to this articles thread this is poor sport.

This is an appeal to the moderators/administator(s) make voting on a post possible only if the user voting has posted in that thread, the tone of the thread shouldn't matter to users who aren't posting in the thread because they either have nothing to say or are too late to post because the option to do so was removed (to all users)


I agree with this. Or drop the comment rating system altogether. Alot of the time the same rater will "1" rate comments that provide opposing viewpoints which means they are rating based their feeling about the poster instead of the post content.
barakn
5 / 5 (7) Oct 26, 2012
Posters of pseudoscientific theories or creationist nonsense are often encouraged to continue posting when replied to, even negatively. Then there are the spammers, and why would we have to comment just to downrate a Viagra add?
rubberman
2.7 / 5 (6) Oct 29, 2012
Posters of pseudoscientific theories or creationist nonsense are often encouraged to continue posting when replied to, even negatively. Then there are the spammers, and why would we have to comment just to downrate a Viagra add?


This is true. However the pseudoscientific posts, when replied to with real science that refutes it, are exposed for what they are. Regardless of how adept they are at plugging their ears and saying "lalalala", they are the only one who can't see, or refuse to see why they are wrong.

But if one can't scientifically refute a post that one considers pseudoscience, one has to take a step back a figure out why, instead of posting a hit and run "1". If it truly is pseudoscience, the holes in it are also easier to see when you take the step back. If I post something that you feel is pseudoscience, I won't debate a clearly flawed stance, show me why my view doesn't doesn't work logically and I'll digress.
barakn
5 / 5 (2) Nov 09, 2012
I don't know about you, but I don't have the time to reply to every fallacious statement.

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