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Extra-solar Planet Imaged
bdb111 writes "European astronomers have taken what may be the first picture of an extra-solar planet. The possible planet orbits a brown dwarf star 230 light years away."
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Here's a link to the ESO press release.
They did identify it as 2M1207 at 230 light years. A quick google suggests this set of coordinates from some Prospero observations in February, coordinates reproduced here (the original file has observation configuration as well):
# Prospero Observation Template File
# Created: 2004 Feb 12 [9:36:32] by saveobs.pl Version 2.2
# For: John Gizis
#
PROJECT=UDEL-04A-0005
IMGTYPE=OBJECT
OBJECT=2M1207
RA=12 07 33.4
DEC=-39 32 54
EQUINOX=2000.0
MODE=DUAL
RA 12, DEC -39 puts it in Hyrda, which according to 5 seconds of looking in "Distant Suns" trial version on my work Windows box, is seriously blocked by the Sun these days. It's about 45 degrees south of Leo, whenever it becomes visible.
Unknown host pong.
If you read the ESO press release you'll see that in addition to imaging it they've also taken spectra of it. The H-band spectrum they shows is similar to other sub-stellar objects, and it also shows fairly strong water absorption bands. This means that it's has to be fairly light. Evolutionary models have been run that predict that this object is about 5 times the mass of Jupiter.
Don't worry, most astronomers don't base their predictions on one image of something, they always follow it up with either multi-wavelength studies or spectral analysis, or both.
This announcement was premature, at best. It is not responsible science.
The planet is not yet confirmed as such. It could very easily be a background star. This has happenned before, and the scientists got an awful lot of egg on their faces. Another unconfirmed "planet" image can be seen here, this one around a white dwarf.
The responsible thing to do is wait a few years to determine if the objects have common proper-motions--if they move through the sky together, they are probably physically linked, and one can determine that the companion object really is a planet. Without this confirmation, the simplest explanation is not that it is a planet.
Many teams of astronomers have images of planet candidates like this one. The responsible astronomers are the ones you aren't hearing from yet--the ones waiting to verify they have planets.
The press-release title should be "A dim spot imaged near a brown dwarf." Any further conclusions have no basis.
The preprint of the paper lists the parent brown dwarf as 2MASS J12073346-3932539 , which is indeed at the above coordinates. The candidate planet (much in the same way Ralph Nader is the candidate president, but there's my bias showing) will be 0.46 arcseconds south and 0.63 arcseconds east.
In case I didn't discourage any amateur astronomers thus far, here's some more: That's a separation of 0.77 arcseconds, when the seeing at most sites is of order 1 arcsecond. The companion is 100 times brighter than the parent brown dwarf in the K band. The parent brown dwarf has a K of about 12, and for an M8 spectral type, that's a V-magnitude of about 19 or 20. For those of you scoring at home, the parent brown dwarf is one million times fainter than anything you can see with the human eye.
The companion is an even redder object, so the colors will be much, much worse at V (there's a reason we try to detect these in the infrared). With a state-of-the-art AO system (look what we did with the same system earlier this year imaging the surface of Titan) on an 8 meter telescope with excellent infrared detectors, the companion lies one magnitude above the detection limit on their sensitivity/separation curves.
Sorry to depress people looking forward to pointing your telescope at this system tonight, but if it makes you feel better, it's probably not a planet.
I just checked that RA, by the way. It's behind the sun right now. You'll have to wait until January to observe it. Or to point your telescope there and not observe it, as the case may be.
>What's a little disappointing is that this planet is orbiting a brown dwarf, which isn't really a star
.
Arguing that it is not a type of star seems questionable. There is a grey area between giant planetary objects and tiny stellar objects. Brown dwarves share properties with both at various times in their evolution.
A Brown dwarf masses between 1 and 8 percent of our suns mass (which is a yellow dwarf). This mass is too small for gravity to produce high enough temperature and pressure in the core to sustain the fusion of hydrogen nuclei into helium 4. However this does not mean that fusion cannot occur. It also does not mean that the surface temperature of the body, or the luminosity of the body are not star-like at some point.
Gravitational contraction alone raises the temperature of the gas considerably. Though the surface temperature of a typical brown dwarf may be as low as 1000K, early in their career the heat generated by their gravitational collapse be be high enough to shine red for a short time. Larger brown dwarves may also have pressures and temperatures at the core sufficient for deuterium and tritium based fusion reactions. The resulting release of energy is futile as it is far too small to even temporarily balance or reverse the gravitationally induced contraction. They couldn't make a go of fusion on the professional circuit, but fusion is fusion. If star-hood is a nuclear club, their amateur standing should count
Yes, they are dim and cool. They can only continue to cool and eventually will radiate weakly in the radio spectrum, as Jupiter and other large gas plants do. However, at some points they may have pretty respectable surface temperatures (perhaps as high as 2500K). At the core they also may fuse some paltry amounts of deuterium and tritium.
On technical grounds this should justify calling them stars, if only briefly. On aesthetic grounds I also think these objects should be cut a bit of slack. The universe is cold and empty enough. Stripping these pitiful gas balls of star-hood entirely seems a bit too harsh.
It seems, from this image, linked from the ESO press release, that we've more than maybe seen the first planet out of our solar system with our own eyes.
It looks like we've also confirmed that brown dwarfs are glowing, white stopsigns. Let's just hope that no one needs to build a space lane straight through our solar system with great-big bulldozer things.
[/lame attempt at humor]
~UP
Eat the Path.
As you get to the very lowest masses of the low-mass stars (about .08 solar masses, or 80 Jupiters), I think you do start getting water lines. The issue is that most stellar photospheres (like our sun's, say) are so hot you can't have molecules of any kind, whereas in cooler stars or brown dwarfs you can. Most people are at least vaguely familiar with the idea of atmoic spectra, where you get some number of sharp (more or less) lines throughout the visible, which, in theory, could be mistaken for one another (it certainly happens for some of the low-strength metal lines). Molecules, on the other hand, have large "bands" of absorption, where light over a large wavelength range is heavily absorbed. It's fun quantum mechanics, but basically the central line is some transition to do with the molecule vibrating (the distance between the oxygen and hydrogen atoms in the water molecule oscillating, say), which is then broadened by a number of transitions to do with the whole molecule rotating.
The end result is you get very distinctive molecular features. See the bottom image on this page on another way of looking for planets, where the black line is the spectrum of the first brown dwarf discovered, Gliesse 229B. Everything in that spectrum redward (longer wavelength) of 1.6 microns is heavily suppresed by methane (another common molecule, CH4)...and I think after about 1.8 you start getting into water bands, too, but don't quote me on that. Anyway, that's all a convoluted way of saying if it looks like water, it probably is water. But there's a large range of planets and brown dwarfs expected to have such water bands in the spectrum (indeed, the parent brown dwarf shows similiar spectral features to the companion)
As to the photo, the data have certainly gone through a lot of processing in the reduction process, but that shouldn't be though of as having photoshopped the result. I've used this same instrument, and there are some features I'm curious about (lack of diffraction spikes from spider arms, mainly), but it seems pretty legitimate. It's just important to realize what this image is showing.
For one thing, that isn't reflected light making the "planet" shine, but rather the planet is powering itself. When you form something like a planet or brown dwarf, and it isn't massive enough to start fusion, gravity will make the object contract. The potential energy of that contraction needs to go somewhere, so half of it heats the gas, the other half comes out as radiation (mostly infrared). As the object ages, the contraction slows, and it gets much fainter. As an aside, even after 5 billion years, Jupiter emits more radiation than it receives from the sun. That's part of the trouble with detecting planets in general, in cases like this we know how much energy is coming out of the object, roughly how old it is, and then we have to rely on theoretical models (which aren't well-tested at all) to tell us how massive the object should be.
The second point is to remember that the "size" of the two objects in that image aren't the physical sizes at all. In fact, the telescope is barely able to resolve the separation between the two, let alone physical structure of the surfaces of these bodies (a scale 10,000 times smaller or so). "Size" of the disk on the detector is simply a matter of our imperfect telescope optics (and basic physics of diffraction) taking the points of lights from parent and companion and smearing them out: brighter objects seem to reach further out on the detector. The diffuse structure near the edge of the bright parent is again introduced by the optics, and isn't a real feature.
The image itself is your typical false-color image. All the data are in the infrared, so for us to see it, a quick remapping has to be done. Rather than have red (0.65 microns), green (0.55 microns), and blue (0.45 microns) filters that are then reproduced by red, green, and blue pixels,