Hubble directly observes planet orbiting Fomalhaut

Nov 13, 2008
This image, taken with the Advanced Camera for Surveys aboard the NASA/ESA Hubble Space Telescope, shows the newly discovered planet, Fomalhaut b, orbiting its parent star, Fomalhaut. The small white box at lower right pinpoints the planet's location. Fomalhaut b has carved a path along the inner edge of a vast, dusty debris ring encircling Fomalhaut that is 34.5 billion kilometers across. Fomalhaut b lies three billion kilometers inside the ring's inner edge and orbits 17 billion kilometers from its star. The inset at bottom right is a composite image showing the planet's position during Hubble observations taken in 2004 and 2006. Astronomers have calculated that Fomalhaut b completes an orbit around its parent star every 872 years. The white dot in the center of the image marks the star's location. The region around Fomalhaut's location is black because astronomers used the Advanced Camera's coronagraph to block out the star's bright glare so that the dim planet could be seen. Fomalhaut b is 100 million times fainter than its star. The radial streaks are scattered starlight. The red dot at lower left is a background star. The Fomalhaut system is 25 light-years away in the constellation Piscis Austrinus. This false-color image was taken in October 2004 and July 2006. Credit: NASA, ESA and P. Kalas (University of California, Berkeley, USA)

(PhysOrg.com) -- Estimated to be no more than three times Jupiter's mass, the planet, called Fomalhaut b, orbits the bright southern star Fomalhaut, located 25 light-years away in the constellation Piscis Austrinus (the Southern Fish).

Fomalhaut has been a candidate for planet hunting ever since an excess of dust was discovered around the star in the early 1980s by the US- UK-Dutch Infrared Astronomy Satellite (IRAS).

In 2004, the coronagraph in the High Resolution Camera on Hubble's Advanced Camera for Surveys produced the first-ever resolved visible light image of a large dust belt surrounding Fomalhaut. It clearly showed that this structure is in fact a ring of protoplanetary debris approximately 34.5 billion kilometres across with a sharp inner edge.

This large debris disk is similar to the Kuiper Belt, which encircles the Solar System and contains a range of icy bodies from dust grains to objects the size of dwarf planets, such as Pluto.

Hubble astronomer Paul Kalas of the University of California, Berkeley (USA) and team members proposed in 2005 that the ring was being gravitationally modified by a planet lying between the star and the ring's inner edge. Circumstantial evidence comes from Hubble's confirmation that the ring is offset from the centre of the star. The sharp inner edge of the ring is also consistent with the presence of a planet that gravitationally "shepherds" ring particles. Independent researchers have subsequently reached similar conclusions.

Now, Hubble has actually photographed a point source of light lying 3 billion kilometres inside the ring's inner edge. The results are being reported in the 14 November issue of Science magazine.

"Our Hubble observations were incredibly demanding. Fomalhaut b is 100 million times fainter than the star. We began this program in 2001, and our persistence finally paid off", says Kalas.

"Fomalhaut is the gift that keeps on giving. Following the unexpected discovery of its dust ring, we have now found an exoplanet at a location suggested by analysis of the dust ring's shape. The lesson for exoplanet hunters is 'follow the dust'", says team member Mark Clampin of NASA's Goddard Space Flight Center.

Observations taken 21 months apart by Hubble's Advanced Camera for Surveys coronagraph show that the object is moving along a path around the star, and so is gravitationally bound to it. The planet is 17 billion kilometres from the star, or about 10 times the distance of the planet Saturn from the Sun.

The planet's upper-mass limit is constrained by the appearance of the Fomalhaut ring. If the planet were much more massive, it would distort the ring, and the effect would be observable in the ring's structure.

"It took the science team four months of analysis and theoretical modelling to determine that Fomalhaut b could not be more massive than three times the mass of Jupiter. Any more massive than that and its gravity would destroy the vast dust belt encircling the star", says Kalas.

Numerous computer simulations show that circumstellar disks will be gravitationally modified by the tug of one or more unseen planets. The Fomalhaut ring has a sharp inner edge that is likely shaped by the gravitational influence of a planet. The inner edge of our Solar System's Kuiper Belt is similarly shaped by the gravitational influence of Neptune.

The planet is brighter than expected for an object of three Jupiter masses. One possibility is that it has a huge Saturn-like ring of ice and dust reflecting starlight. The ring might eventually coalesce to form moons. The ring's estimated size is comparable to the region around Jupiter that is filled with the orbits of the four largest satellites.

Because the Fomalhaut system is only 200 million years old, the planet should be a bright infrared object. That is because it is still cooling through gravitational contraction. However, ground-based telescopic observations at infrared wavelengths have not yet detected the planet. This also sets an upper limit on its mass because the bigger the planet, the hotter and brighter it would be.

Kalas and his team first used Hubble to photograph Fomalhaut in 2004, and made the unexpected discovery of its debris disk, which scatters Fomalhaut's starlight. At the time they noted a few bright sources in the image as planet candidates. A follow-up image in 2006 showed that one of the objects is moving through space with Fomalhaut, but changed position relative to the ring since the 2004 exposure. The amount of displacement between the two exposures corresponds to an 872-year-long orbit as calculated from Kepler's laws of planetary motion.

Fomalhaut moves across the sky at 0.425 arcseconds per year, which is the apparent width of 1 Euro coin as seen from 12 kilometres away.

The planet mysteriously dimmed by a factor 1.5 between the 2004 and 2006 observations. This might mean that it has a hot outer atmosphere heated by bubbling convection cells on the young planet – sort of a Jupiter on steroids. Or, it might come from hot gas at the inner boundary of a ring around the planet.

The planet may have formed at its location in a primordial circumstellar disk by gravitationally sweeping up remaining gas. Or it may have migrated outward through a game of gravitational billiards, where it exchanged momentum with smaller planetary bodies. It is commonly believed that the planets Uranus and Neptune migrated out to their present orbits after forming closer to the Sun and then gravitationally interacted with smaller bodies.

Fomalhaut is much hotter than our Sun, and 16 times as bright. This means a planetary system could scale up in size with a proportionally larger Kuiper belt feature and scaled-up planet orbits. For example, the "frost line" in our Solar System – the distance where ices and other volatile elements will not evaporate – is roughly at 800 million kilometres. But for hotter Fomalhaut, the frost line is at roughly 3 billion kilometres from the star.

Fomalhaut is burning hydrogen at such a furious rate through nuclear fusion that it will burn out in only one billion years, which is 1/10th the lifespan of our Sun. This means there is little opportunity for advanced life to evolve on any habitable worlds the star might possess.

Future observations will attempt to see the planet in infrared light and will look for evidence of water vapour clouds in the atmosphere. This would yield clues to the evolution of a comparatively newborn 100-million year-old planet. Astrometric measurement of the planet's orbit will provide enough precision to yield an accurate mass.

The NASA/ESA/CSA James Webb Space Telescope (JWST), scheduled to be launched by ESA in 2013, will be able to make coronagraphic observations of Fomalhaut in the near- and mid-infrared. JWST will be able to hunt for other planets in the system and probe the region interior to the dust ring for structures such as an inner asteroid belt.

Source: Hubble Information Centre

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thales
3.3 / 5 (3) Nov 13, 2008
SO AWESOME!!
NeilFarbstein
2.3 / 5 (6) Nov 13, 2008
What will happen when an earth like planet is discovered. There might be real rush to design a star ship.
RigorMan
3.4 / 5 (5) Nov 14, 2008
Dear NeilFarbstein, a spaceship to do what? Manned?
Formalhaut is 25 lightyears away from earth, that means
25 *ly ~2.4*10^14 km
If you take an exaggerated velocity of 200 km/sec (voyager is going at around 17 Km/sec!) then you'll see that it takes around 37.000 yers to get there. So the spaceship MUST be unmanned, that limits the scope of the mission.
Let's say that you want to d othe trip in 50 years, it means you've to reach a velocity of half the velocity of light (c/2).

Suppose you want to send a spaceship with a mass of a 1000 tons (i guess this is small, right?)
the required energy is roughly:
E=1/2*m*(c/2)^2 = 1.125*10^22 J

A barrel of crude oil contains about 6*10^9 J
that means you need the equivalent of 1.8*10^12 barrels.
Or you might want to use nuclear fuel, in that case you'll need 152000 tons of Uranium-235.
I guess you can't hope to do that with current technology.

I would be content with a basketball-size probe
that will get there in 300-400 years!!!!!!

LeeSawyer
3.7 / 5 (3) Nov 14, 2008
How about a dedicated high-intensity radio signal that gets there in 25 years? The SETI project can detect the equivalent of a cell phone on the moon. But the Formalhaut system is probably too young.
smiffy
1.7 / 5 (3) Nov 14, 2008

I would be content with a basketball-size probe
that will get there in 300-400 years!!!!!!



How could the probe be braked? How would it come back?
D666
4.3 / 5 (7) Nov 14, 2008
Dear NeilFarbstein, a spaceship to do what? Manned?


Oh, come on, Rigorman! It's easy. You get a hunky yet socially stunted male scientist, a gorgeous yet damaged female scientist, a physically unimpressive social outcast / genius who never graduated high school but knows more about everything than anybody, and a by-the-book military martinet who has a secret past that shows he actually has a heart. Put them all in a room together, tell them that the Earth is about to be destroyed unless they can invent a fix. Let simmer for 24 hours, cool with lid removed, and viola! Instant FTL drive.

Hey, it's worked every other time!
holmstar
3.8 / 5 (4) Nov 14, 2008

I would be content with a basketball-size probe
that will get there in 300-400 years!!!!!!



How could the probe be braked? How would it come back?


Simple, either it wouldn't slow down at all (fly-by) or it would slow down the same way that it accelerated in the first place.

And it wouldn't bother coming back. One-way trip.
smiffy
2.5 / 5 (2) Nov 14, 2008
Simple, either it wouldn't slow down at all (fly-by) or it would slow down the same way that it accelerated in the first place.


To get to the system in 400 years the probe would have to attain a speed of c/16. That's over 11,000 miles per second. Some fly-by. It would need some pretty nifty cameras on board to get more than a few blurred stills at that pace.

As far getting back - what power system would be used to accelerate the 'basket-ball' sized probe to a speed of 23,000 mps if it was to return in another 400 years?

And it wouldn't bother coming back. One-way trip.


I suppose the same terrific power source is going to be used to transmit the data back home? Our telescopes can only just pick up an entire big hot planet's EMR.
thales
3 / 5 (2) Nov 14, 2008
I suppose the same terrific power source is going to be used to transmit the data back home? Our telescopes can only just pick up an entire big hot planet's EMR.

That's a good point, but the planets' EMR is undirected. Of course it would depend on the dispersion rate etc, but I would imagine a laser pulse directed at Earth would be effective without having to be super-powerful. Especially if it were a "squeezed" laser pulse.

http://www.physor...240.html
smiffy
3 / 5 (2) Nov 14, 2008
I would imagine a laser pulse directed at Earth would be effective without having to be super-powerful.


It would have to be a very well-collimated laser!
And the more collimated it is the more fantastic the aiming mechanism would have to be to hit the moving Earth in 25 years time! Puts Star Wars to shame!

I mean it's great news about photographing this planet. But don't get carried away!
yyz
3 / 5 (4) Nov 14, 2008
I think in the short term, astronomers would be most interested in obtaining spectra, polarization data, magnitudes (and any variations) and alternative methods for deducing these new planet's mass, orbital period, etc. Spectra alone of these new planetary systems, while difficult to obtain, would contain a wealth of info on the physical makeup and numerous other properties of these worlds impossible to obtain with current spectroscopic line-shifting detections of planets and be a big improvement compared to spectra deduced from planetary-transiting systems. Add to that just the aesthetic value of actually seeing a planet orbiting another star...what a way to stir up childrens (and adults) imaginations. These new direct observations were certainly predicted to occur well within our lifetimes, but where and how to look is now seriously being addressed.
NOM
3.7 / 5 (3) Nov 16, 2008
Another thing they will want to do is determine any orbital variations that predict the position of inner planets.
robbycoats
2.5 / 5 (2) Nov 16, 2008
[
How could the probe be braked? How would it come back?


Once it reaches the target star system, perhaps it could deploy a solar-wind brake...
robbycoats
3.7 / 5 (3) Nov 16, 2008
I would imagine a laser pulse directed at Earth would be effective without having to be super-powerful.


It would have to be a very well-collimated laser!
And the more collimated it is the more fantastic the aiming mechanism would have to be to hit the moving Earth in 25 years time! Puts Star Wars to shame!

I mean it's great news about photographing this planet. But don't get carried away!


Aiming wouldn't be THAT big of a deal; even a laser beam would be so diffuse and spread out by the time it got here, you could likely detect it from from any point in the solar system. From the probes perspective, it would probably just aim at the sun.
smiffy
5 / 5 (1) Nov 17, 2008
Aiming wouldn't be THAT big of a deal; even a laser beam would be so diffuse and spread out by the time it got here, you could likely detect it from from any point in the solar system. From the probes perspective, it would probably just aim at the sun.


That's right. If you take the laser they use to determine the Moon's position as an example. It diverges to about 1 mile on the moon's surface. Scaling the distance up from 240,000 miles to 25 light years gives a divergence of 6 x 10^8 miles (by my back of the envelope reckoning), comparable with the size of the Solar System, as you say.

The problem with this is how little power would be left for a telescope to pick up. By more rough reckoning and provided I haven't made a miscalculation I estimate that the power received by a telescope with say a 30 ft collector would be about diminished by a factor of 10^22. Even with a very juicy 1000 Watt diode laser (which hasn't been built yet) and which would be difficult to fit on a small probe you're only left with 10^-19 Watts. I'm not an expert in what telescopes can manage or what the background noise levels would be, but that figure looks very small to me.
Modernmystic
2.5 / 5 (4) Nov 17, 2008
Dear NeilFarbstein, a spaceship to do what? Manned?
Formalhaut is 25 lightyears away from earth, that means
25 *ly ~2.4*10^14 km
If you take an exaggerated velocity of 200 km/sec (voyager is going at around 17 Km/sec!) then you'll see that it takes around 37.000 yers to get there. So the spaceship MUST be unmanned, that limits the scope of the mission.
Let's say that you want to d othe trip in 50 years, it means you've to reach a velocity of half the velocity of light (c/2).

Suppose you want to send a spaceship with a mass of a 1000 tons (i guess this is small, right?)
the required energy is roughly:
E=1/2*m*(c/2)^2 = 1.125*10^22 J

A barrel of crude oil contains about 6*10^9 J
that means you need the equivalent of 1.8*10^12 barrels.
Or you might want to use nuclear fuel, in that case you'll need 152000 tons of Uranium-235.
I guess you can't hope to do that with current technology.

I would be content with a basketball-size probe
that will get there in 300-400 years!!!!!!



Yeah I bet there would be a lot of naysayers about interplanetary travel in the 1700-1900s using large canvas sheets as sails. After all what would push against them etc...

"Clarke's First Law: When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong."

Read the second, and third laws too. Also the law of revolutionary ideas is instructive as well.
D666
5 / 5 (2) Nov 18, 2008
Yeah I bet there would be a lot of naysayers about interplanetary travel in the 1700-1900s using large canvas sheets as sails. After all what would push against them etc...


Yes, but in the 1700-1900's, such a feat *would* be impossible, or prhibitively expensive using existing technology. The error is assuming that our current level of tech is all there is, or that it at least predicts all there can be.

The number of times I've heard some variation on "We know all there is to know" is astounding, and so far they've been spectacularly wrong every time.

So the naysayers are technically right, but their implied message that we shouldn't even bother is the real problem IMO.
Austriak
1 / 5 (1) Nov 20, 2008
About: %u201C Hubble Directly Observes a Planet Orbiting Another Star%u201D

THIS SYSTEM CAN BE VERY OLD, AND NOT YOUNG!
Interesting news ! Heartiest greetings to the Hubble team & NASA team.
But... the news has contradictions with known theories and it was a prediction 20 years ago from the Universal Matrix Theory. Are there wrong interpretations from Hubble%u2019s collected data? Let%u2019s see the following:

1) It is possible that the body is not a planet, anymore. It is brighter than the expected. It can be a very old planet going to be a pulsar;

2) The excess of dust around the star can be disposable material from an old, dying star, and not about a young star;

3) Maybe the star is not so different from the sun, about long life. The sun can reach 10 billions years. We have a lot of data from the sun. We have few data from that star. Who could authorize us to say there is star living only 1, 2 billion years? Everything is suggesting the star has the same time of life like any other star. Our models are suggesting the star is about 7 billions years old.

The Universal Matrix models ( http://theuniversalmatrix.com ) suggests that old stars produces dust while its combustible is finishing, like any other fire you see at Earth. When the star become old, its planets are old also, they begin to be brighter, till becoming a pulsar. The tiny edge at the dust can be the initial formation of a new black hole, as we can see at the models.
By the way, congratulations and thanks for the good job. We work with data like that to testing our models%u2026

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