View Full Version : Astronomers Photograph Extrasolar Planet!

John L
2005-Apr-01, 08:07 PM
I just read this on CNN.com (http://www.cnn.com/2005/TECH/space/04/01/extrasolar.planet.photo/index.html)!!! :o

The star is GQ Lupi, the planet is about 2 Jupiter masses, and it orbits the star at about 100 AU.

And the preprint (http://fr.arxiv.org/PS_cache/astro-ph/pdf/0503/0503691.pdf) is available, too.

2005-Apr-01, 11:05 PM
Good catch, JohnL. I read the abstract earlier today, but at your insistence, read the text just now. I consider the existence, position and spectral data to be solid, but the inferred mass (as the authors themselves admit) is seriously model-dependent. Since our models for this type and age of star are unsettled at best(okay, mutually contradictory), the mass estimate may be off by almost 2 orders of magnitude. Also, the spectrum was curtailed at both ends by extinction from terrestrial atmosphere [insert rant about needing more/better space telescopes].

Carping aside, this is a beautiful example of scientific work, pushing the equipment to its limits, and showing extraordinary cleverness in methodology. Beautiful!!
:D Steve

2005-Apr-02, 04:53 AM
Wow! And that is all reflection?

100 au is a large seperation. It would be interesting to find a planetary system that reflects our early system, watch evolution from the comfort of Earth. :)

2005-Apr-02, 02:10 PM
Wow! And that is all reflection?

No way. Assume for the sake of discussion that the primary is as luminous as the sun (actually, it is somewhat dimmer). The planet is 25 times as far out as Jupiter, so it would receive 1/625 as much illumination as Jupiter does in our system. At 2000K, it emits much more radiation of its own than it reflects. Most of this is the heat of formation (the kinetic energy of the gas, given up by the collapse into a blob), but given the range of allowable masses, some of the heat may be from the fusion of Lithium near its core. This is a temporary process, as the Lithium is soon used up, and the reaction does not generate enough energy to catalyze any further processes. If it's toward the high end of the mass range, it may also be fusing any Fluorine that was picked up during formation, but the same arguments apply. Best regards-- Steve

2005-Apr-04, 05:26 AM
There could be planets not yet detectable in between the star and this huge planet so hold your breath, Zephyr.

2005-Apr-04, 05:45 AM
This is likely the most exciting exo-planet find yet. I made a point to bookmark it.

2005-Apr-04, 05:48 AM
BTW, with it's great distance from it's parent star getting more photos and measurements should be very easy to accomplish. :P

2005-Apr-08, 03:32 PM
Well guys, may be I will pour some cold water on your enthusiasm... but the news are dated April 1st...
..and I seriously doubt that such image can be obtained at 100 ly, with a 2 Mj planet !!! The temp. of the planet they indicate is good for IR only... and the pic has been taken by the VLT which is not IR.
The site (unfortunately in french) http://www.flashespace.com/html/avril05/06b_04.htm also mentions very serious doubts about this discovery... suspecting an April's fool joke that may be has gone beyond what its author expected!
If real, the "planet" looks more probably a brown dwarf...

2005-Apr-08, 10:14 PM
I stand by my earlier comments. The results claimed by the authors were obtained in the near-infrared. A telescope optimized for visible light still operates quite well there. The following combination makes the results plausible: (high-altitude telescope) + (large aperture telescope) + (extremely good pointing accuracy) + (adaptive optics) + (deconvolution software) + (CCD imaging) + (smart astronomers) = (believable results) + (known error limits)

In the source document, the authors note explicitly that the estimated mass has a wide range of error. They only managed to prove that the two objects were comoving-- not that the smaller was in orbit about the larger. The horizontal separation would be 100 AU if they were exactly at the same distance. No orbital motion was detected, only a common proper motion.

You may, of course, believe what you wish. Best regards-- Steve

John L
2005-Apr-08, 11:00 PM
This story is now on the Universe Today News page, so I'm sure our gracious host has looked into the issues...

2005-Apr-11, 12:34 PM
My mistake, sorry about that !!!! After a second look, I must admit I was a bit hard... and flashespace was a bit hard too !!!! The news is clearly a very serious one, official ESO press release and to be published shortly in A&A (Astronomy & Astrophysics, publication already accepted) !!!
However as mentioned by Steve, quite a large error/uncertainty range on the mass, between 1 Mj and 42 Mj.
More info at: http://www.obspm.fr/encycl/GQ-Lup.html