Marley notes that Kalas and his colleagues saw the exoplanet at two different wavelengths from Hubble, but attempts to see it from the ground failed. As a result, they lacked data points describing the object and, so, still had to make some inferences about it.
"If you look at the other exoplanet discoveries, or shall I say the other candidate exoplanets found by ground-based observations, the contrast [between them and their stars] is a factor of 10,000 or 100,000," Kalas says. "The contrast between Fomalhaut b and the central star is 100 million. And it's impossible to get this from the ground" in visible wavelengths. "Our selection is fairly rigorous and conservative. There may be specks in there that are also planets, but we've not been able to confirm them as such. Fomalhaut b is the most rigorously tested."
Marois and his team used ground-based infrared detection to seek out exoplanets around nearby, young, massive stars—those whose planets would have wide orbits and emit significant amounts of radiation as they cool from their relatively recent births millions of years ago. After narrowing some 80 candidate stars to 20 "really, really interesting" ones with infrared excess (indicating the presence of orbiting dust), the researchers settled on a particularly appealing star.
"For HR 8799, the infrared excess was consistent with dust orbiting at around 80 astronomical units," or roughly 80 times the distance from the Earth to the sun (7.4 billion miles, or 11.9 billion kilometers), Marois says. "And that's usually a sign of planet formation, the residue of the planet formation. So that's usually a very good sign."
By comparing data captured by various telescopes in 2004, 2007 and this year, Marois's group selected three objects, all estimated to be below the brown dwarf threshold, orbiting HR 8799. "These are the first images of a multiplanet system, but these are as well the first detections of planets at separations that are similar to the outer planets of our own solar system," Marois says. The innermost exoplanet around HR 8799 has an orbit that would place it between Uranus and Neptune in our solar system. (Fomalhaut b, by contrast, orbits at nearly twice the distance of the farthest-flung planet around HR 8799, albeit around a larger star.)
"Kepler himself would recognize these as planets," Marley says, referring to the German astronomer Johannes Kepler, who formalized his laws of planetary motion in the 17th century. "You can see the planets in close to circular orbits, you can see them moving, and this system also has a dust disk, as people now believe our own solar system out beyond the orbit of Neptune has."
Marley acknowledges that the exact mass of the objects could be called into question, even pushing two of the masses into the realm of brown dwarfs, but does not view that uncertainty as a deal-breaker given the magnitude of the discovery.
Further characterization of the objects from both groups will enhance astronomers' understanding of star and planet formation. Toward that end, Kalas is awaiting the repair of the Hubble's Space Telescope Imaging Spectrograph, which failed in 2004, to give a more detailed look at Fomalhaut b. Hubble could also help confirm the exoplanet's status next year by photographing it farther along its predicted orbital path. As for Marois, "there are actually two other objects that we're tracking" around another star, he says. "We're not sure if these are background objects or planets, so we're going to be confirming these next summer."
UPDATE: Click here to listen to a podcast about the exoplanet discoveries.
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10 Comments
Add CommentI disagree that these amazing images can be characterized as "the first" images of exoplanets. What about 2M1207b, which is smaller than a brown dwarf? Or the planet of 1RXS J160929.1-210524, another relatively low-mass object? I wrote an article (http://www.brighthub.com/science/space/articles/11698.aspx) on images taken of these two objects a month ago. The first image is about four years old and the newer one is from earlier this year. Did you miss something, SciAm, or are you disputing that these masses qualify as planets?
Reply | Report Abuse | Link to thisAwesome pics, but I sure am glad that someone else caught that comment. What about the previous exoplanets?!?
Reply | Report Abuse | Link to this@Ginko100: don't be surprised 2M1207b is ignored, it's just because it was discovered at ESO, not by an US astronomer ! That kind of things happens. By the way, I liked your article.
Reply | Report Abuse | Link to thisWhen are we going to see hubble shots of Zeti Reticuli? Why aren't there any?
Reply | Report Abuse | Link to thisWould it be possible, or has it been confirmed that thare are any planets around the Zeta Retuculum star, as claimed by Betty & Barney Hill in 1961 ?
Reply | Report Abuse | Link to thishttp://en.wikipedia.org/wiki/Betty_and_Barney_Hill_abduction#.22Deciphering.22_the_star_map
With all this high powered technology, when will we get confirmation if there are any plantes around Zeta Reticulum as claimed by Betty & Barnie Hill in 1961 ?
Reply | Report Abuse | Link to thishttp://en.wikipedia.org/wiki/Betty_and_Barney_Hill_abduction#.22Deciphering.22_the_star_map
how is it that not one reputable scientist has the guts to admit that we have ongoing, one-on-one, proven, civilian et contact. Try www.thayfly.com. for the real exo-planets news and science, instead of these Govt controlled, highly censored so called Journals tidbits of misinformation.
Reply | Report Abuse | Link to thisIf they actually do look at Zeta Reticuli, a bunch of right-wing numbskulls will cry how its a waste of taxpayer money, and use that as a reason to slash NASA's budget. Remember how many times McCane kept whining about that million-dollar projector for a planetarium?
Reply | Report Abuse | Link to thisProbably because "in addition to the stunning, still irreproducible physical evidence, Meier has single-handedly transcribed more than 24,000 pages of information," makes Biller Meier nearly as credible as Richard Hoagland, who has absolutely zero credibility outside of those who wear tinfoil hats and talk about black gov't shush-copters performing mind-control operations on the general population.
Reply | Report Abuse | Link to thisIf the evidence is "still irreproducible" it probably means it's fake. Funny how the website actually spins this little tidbit as something that gives it credence.
Ungolythe expsoes himself as a misniformer by insulting those that accept the work of Meier and Hoagland.
Reply | Report Abuse | Link to this6 US ivestigators spent 5 years on and off with Meier in Switzerland during the time of the main et contacts, in a serious effort to debuk hum. They faiked to do so and ended up confirming his et contacts.
They then published Light Years by Gary Kinder, the events of of the itnvestigation.
One of the Meier`s support group, GuidoMossbrugger pubished Amd yet..They Fly, with many Meier photos.
Of the 1000 plus Kodak color pre-photo-shop photos that Meier took, approx 100 were anaylysed by JPL in CA. USA. They confirm a solid, metallic, energised, object in the distance.
One analysis shows a beamship in the close proximity of a Swiss AF Mirage jet fighter, with an energy field from the beamship enveloping the jet fighter. This incident is recorded in the contact notes of Meier, with the ers. (1600 pages translated to English and published by Wendel Stevens USAF Intel Rtd, (another tin-hat)?
The et pilot confirmed that the fighter had just locked on its firing control to the beamship, and the beamsip pilot had to neutralize that mechanism at that instant.
Metal fragments of the beamship hu
ll cnstruction stages given to meier by the ets, were analysed by the then top IBM scientist Marcel Vogel, inventor of the computor disk, (and dayglo colors)!
In the videoed analysis, Vogel found metals of absolute purity bonded to other metals also of absolute purity in a process unknown-on earth.
The millions who accept these visits to be factual ignore the tinhat insults, and the screams of fraud from various quachbusting sites.
How arrogant to think that we are alone in this massive universe,