Posted on 04/29/2005 10:22:03 PM PDT by neverdem
A reddish speck photographed near a dim and distant star last year is indeed a planet, about five times the mass of Jupiter, an international team of astronomers is reporting today.
They say the results bolster their claim, put forward last fall, that this image was the first of a planet orbiting a star outside the solar system.
The planet, about 230 light-years from Earth in the constellation Hydra, orbits a kind of failed star known as a brown dwarf at a distance of at least five billion miles, twice as far as icy Neptune is from our own Sun. Spectroscopic measurements show water vapor in its atmosphere, suggesting that it is cold like a planet and not hot like a star.
"This discovery offers new perspectives for our understanding of chemical and physical properties of planetary mass objects as well as their mechanisms of formation," Dr. Gael Chauvin of the European Southern Observatory in Chile and his colleagues wrote in the paper, in the journal Astronomy and Astrophysics.
When Dr. Chauvin's group first announced the discovery of the object, known officially as 2M1207b, last year, they admitted that they could not prove that it was not just a background object unrelated to the brown dwarf. Subsequent observations using the Very Large Telescope on Cerro Paranal in northern Chile and a system designed to take the twinkle out of starlight and thus get sharper images showed that the dwarf star and the suspected planet were moving together across the sky, cementing the notion that they are gravitationally bound.
Measurements of the same system with the Hubble Space Telescope are to be reported on Monday in Baltimore at a meeting on extrasolar planets.
In the last decade, astronomers have detected, by indirect means, some 150 planets around other stars, setting off a race to see these objects in their own light. Such observations will allow them to study the composition and other properties of these "exoplanets" and compare them to the denizens of the solar system and to one other.
In the year it has taken the European group to cement its claim, other groups have claimed to have seen the first light from extrasolar planets. Last month, for example, a group led by Dr. Ralph Neuhäuser of Jena University in Germany, using the same telescope and camera, reported that they had imaged a planet of two Jupiter masses circling the star GQ Lup. But some astronomers have questioned the reliability of their estimate of its mass, arguing that it could be heavy enough to be a brown dwarf.
In a second paper, to appear in the same journal, Dr. Chauvin's team is reporting another discovery, of a companion to the star AB Pictoris, a young star about 150 light years from Earth. That object, known as AB Pic b, is about 13 or 14 times the mass of Jupiter, they estimate, putting it right on the line between planets and brown dwarfs.
Like the earlier planet and GQ Lup, AB Pic b is orbiting at an enormous distance from its star, 23 billion miles, and that is a new puzzle for the planet hunters, Dr. Ben Zuckerman of the University of California, Los Angeles, a member of the team, said. Dr. Zuckerman noted that these were very far out compared with any previously known planets, which raised questions about how and where they had formed.
"It's a new kind of system," Dr. Zuckerman said, adding that they are also rare. "They are relatively few and far between."
I just did some googling. Yup, appears you're correct. About 80 Jupiter masses is what's required to ignite into a star. Huh. Cool, learned something. Which is: don't trust Arthur C. Clarke *evil grin*.
http://www.badastronomy.com/bad/misc/jupiter_galileo.html
Qwinn
The way I read it last year, this was never in doubt. Hmmmmm. I wonder.
Bad Astronomy is an A-OK site, I highly recommend. :)
A lot of astronomy involves triple/quadruple checking.
They wanted to watch the set move in the sky over a significant period to be absolutely sure that they were gravitationally bound.
IIRC, they had other indirect evidence, but this is the first image.
No, last year they had imaged this planet initially but they were unsure if it was a companion object.
It had to be watched over a period of time to compare movement to background stars.
Prior to this, yes, all planets were detected indirectly.
If you look real hard you can see the little green man waving the sign "Hi, Mom!"
Thanks for the link.
This is an interesting link: How to distinguish brown dwarfs from planets.
http://encyclopedia.lockergnome.com/s/b/Brown_dwarf#Distinguishing_light_brown_dwarfs_from_large_planets
Honestly, this info is causing me to have to redefine my terms. I pretty much always thought that a categorization as a star (which I believed included brown dwarfs) required ongoing fusion. But according to this, apparently not. Then again, they don't seem to be sure themselves how to classify it, since one minute they refer to it as "sub-stellar" and another minute they do call it a star. Frankly, without having ever undergone fusion, I would've called it a heavy planet. But I can see how the fact that it's uniform like a star (not much difference in chemical makeup based on depth) takes it out of the planet category too. Interesting. For about ten minutes. Think I'll go back to devoting my attention to the cool stuff like black holes/quasars/pulsars ;)
Qwinn
I haven't read Arthur C. Clarke, so I can't help you.
Its the lack of defining characteristics and a large statistical base to operate on.
Same issue we're having with planets and arguements on whether Pluto should be downgraded or Sedna upgraded (etc)
For immediate release
Among the most essential quests of modern astronomers, taking direct images of planets outside of our solar system is certainly up there among chart-toppers. Obtaining such images of a so-called exoplanet would enable scientists to study in detail the physical nature of the object and, in particular, to analyse the composition of its atmosphere. The astronomers' ultimate goal is of course to perform such analysis for earth-sized planets, in the hope of detecting a telltale signature of extraterrestrial life.
Such an ultimate objective is still at least decades in the future, as earth-size and even Jupiter-size planets around stars as old as the Sun are too faint to be detected by present-day technology.
Nevertheless, great progress can be achieved by taking images of giant planets orbiting much younger objects. Because giant planets a few tens of millions of years old are much hotter and brighter than their older brethren, they can be much more easily detected. Moreover, as the first tens of millions of years are considered to have been a critical period in the formation of Earth and of our own solar system, the study of nearby young planetary systems provides astronomers with invaluable insight on our own origins, something that is difficult if not impossible to decipher from investigation of old, mature planetary systems.
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See link for the rest of the press release.
Thanks for the link.
Red Speck Bump
Check comments# 5, 13, 14, 16 and 18 if you don't read the whole thread.
No, it was in 2010 that Jupiter gets ignited into a star, of that I'm absolutely sure. It was a good book, better than 2001 IMHO. In the very very lame sequel 2061, he expands on the consequences of Jupiter being a star and the availability of all the diamond that was ejected from the initial ignition (space elevators, etc.). In the utterly benighted and horrible 3001... well, frankly, it was just too awful to be described.
Qwinn
And posts #21, 23 and 29. I had the same objection you did, but that issue has been resolved.
Qwinn
Doh, post #39 was meant for fish hawk, not neverdem.
Qwinn
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