# Most earthlike exoplanet yet (ESO team 23 April)

1. Apr 24, 2007

### marcus

2. Apr 24, 2007

### neutrino

Why hasn't this news appeared in more reliable sources of astronomy-related news? And more importantly, where is the press release from ESO?
http://www.eso.org/outreach/press-rel/pr-2007/

3. Apr 24, 2007

### neutrino

4. Apr 24, 2007

### baywax

That's so cool. Its kind of errie thinking about some red dwarf system, 20 light years away, with a planet whizzing around the sun in 13 days and the possibility that it has oceans and everything oceans come with.

Any chance that SETI is directing some of its efforts toward the Gliese 581 system? I'd think that would be a good candidate for eaves dropping.

5. Apr 24, 2007

### OSalcido

http://news.yahoo.com/s/ap/20070424/ap_on_sc/habitable_planet

where the heck did he pull this from? how can he say it is "probably full of water"? I mean, Venus and Mars are in the solar system's goldilocks zone.... and there's no appreciable amount of water on either one of them. that's a 66% chance of not having water, right? am i missing something?

6. Apr 25, 2007

### baywax

I just want to thank Marcus for posting this info a day or two ago. Today its all over the front page of the papers. I feel pretty ahead of the times having seen it first here on PF Actually the national news had some good animations showing the probabilities involved with the Gliese 581 system a day after I saw this thread. Good working it Marcus!

Last edited: Apr 25, 2007
7. Apr 25, 2007

### cesiumfrog

The front cover of The Australian (newspaper) today includes "WE ARE NOT ALONE Earth-like planet found" which seems a sensationalist leap from the actual (p.3) story content "It's too soon to be certain that GL581c is a rocky planet like Earth or a gas planet like Neptune." Accompanied by the highly detailed (photograph-like) "illustration"..

8. Apr 26, 2007

### OSalcido

Furthermore..... its not even around a sun-like yellow star. It's orbiting a tiny Red Dwarf and it's much closer to it's star. I know some reddwarfs are prone to violent solar flares that would blast this planet into a barren moonscape if it ever got hit by one.

9. Apr 26, 2007

### Chronos

Actually, red dwarf stars are probably the best place to look for earthlike exoplanets. They are extremely abundant and extremely long lived. And planets orbiting them are much easier to detect due to their relatively small mass [which magnifies the gravitational perturbations] and low intrinsic brightness. The part of the article about abundant water is purely speculative, albeit not unreasonable. Water appears to be fairly abundant in our solar system and the universe in general. A nice, temperate planet with decent gravity is the logical place to look for it in liquid form. It may already be detected in the atmosphere of at least one exosolar planet:

http://www.astrobio.net/news/article2298.html

10. Apr 26, 2007

### Staff: Mentor

Well, it's PopSci - science for appeal to the general public, so the statements are designed to capture the imagination.

I don't think Venus is in the Goldilocks zone since the atmospheric and surface temperatures is rather high, and the atmosphere is not too hospitable to most life with we are familiar. I think Mars is too far out, so the night time temps would be too low, but perhaps under the surface life might have a chance.

Whatever water Venus has is mostly tied up as sulfuric acid, so little actual free water might exist. Apparently the atmosphere (which is mostly CO2 (~96%) and N2 (~4%)) has traces of water vapor.

Good points, and it is about 0.073 AU or 11 million km from the red dward, yet the astronomers are apparently projecting average surface temperature of 0–40 °C (32–104 °F). The atmosphere would certainly be denser than earth's.

http://en.wikipedia.org/wiki/Gliese_581_c

I wonder about the magnetic field.

11. Apr 26, 2007

### dimensionless

I would say that it is worthy of reporting. I would also point out that water is very plentiful in this solar system.

12. Apr 26, 2007

### matt.o

Actually, water is one of the most abundant molecules in the Universe. It is found in star formation regions and cold molecular clouds. The 22GHz water maser line is the strongest spectral line observed in the radio Universe.

13. Apr 26, 2007

### Wallace

Slightly tangential question here, but is anyone aware of the state of spectral observations of extra solar planets? I know it's never been done but I think there are efforts to try and do it, but I'm not much of an observer so I'm not sure of the state of the art.

It seems logical to me that the presence of $$O_2$$ in the atmosphere is a far clearer indicator of life than the existence of liquid water on the surface, but much harder to infer of course!

14. Apr 27, 2007

### Garth

In terms of relative abundance in the 'cosmic mix', the most abundant element is hydrogen (~75%), then helium {~23%) and the next most abundant element is oxygen (~1%), after which comes carbon (~0.5%). Everything else, including the silicon and iron of our own Earth planet, is to be found in the remaining ~ 0.5%! (% by mass).

It is therefore to be expected that water is actually the most abundant molecule in the universe!

The trick is finding it in liquid form.

Garth

Last edited: Apr 27, 2007
15. Apr 27, 2007

### Garth

I agree that the signature of free oxygen is life's 'smoking gun' to look out for.

This paper on today's ArXiv may be pertinient. Detailed Models of super-Earths: How well can we infer bulk properties?.
Fancy a swim anybody?

Garth

Last edited: Apr 27, 2007
16. Apr 27, 2007

### baywax

Hello Wallace...

I dug this up for you. Its just an abstract but goes into some detail with regard to your question.

From: http://www.cosis.net/abstracts/COSPAR04/02478/COSPAR04-A-02478.pdf

You might have to email the M. Ollivier to get the main body of the text.

Also a thought to consider is that life may be starting in the form of anaerobic bacteria on the planet in question and would therefore not require O2.

Last edited: Apr 27, 2007
17. Apr 27, 2007

### baywax

Some what related....... from Science Actualitiés, Friday, April, 27 (French)

http://www.cite-sciences.fr/francai...u/question_actu.php?id_article=3303&langue=an

Sorry, just another quote from the same page.

Last edited: Apr 27, 2007
18. Apr 30, 2007

### marcus

The Udry et al technical journal article for this just became (finally!) available on the arxiv.

http://arxiv.org/abs/0704.3841
The HARPS search for southern extra-solar planets XI. Super-Earths (5 & 8 M_Earth) in a 3-planet system
S. Udry (1), X. Bonfils (2), X. Delfosse (3), T. Forveille (3), M. Mayor (1), C. Perrier (3), F. Bouchy (4), C. Lovis (1), F. Pepe (1), D. Queloz (1), J.-L. Bertaux (5)
(Submitted on 29 Apr 2007)
Revised version resubmitted to A&A Letters, 5 pages, 4 figures

"This Letter reports on the detection of two super-Earth planets in the Gl581 system, already known to harbour a hot Neptune. One of the planets has a mass of 5 M_Earth and resides at the 'warm' edge of the habitable zone of the star. It is thus the known exoplanet which most resembles our own Earth. The other planet has a 7.7 M_Earth mass and orbits at 0.25 AU from the star, close to the 'cold' edge of the habitable zone. These two new light planets around an M3 dwarf further confirm the formerly tentative statistical trend for i) many more very low-mass planets being found around M dwarfs than around solar-type stars and ii) low-mass planets outnumbering Jovian planets around M dwarfs."

Authors' institutions:
((1) Observatoire de Geneve, Université de Geneve, Switzerland, (2) Centro de Astronomia e Astrofisica da Universidade de Lisboa, Portugal, (3) Laboratoire d'Astrophysique, Observatoire de Grenoble, Universite J. Fourier, France, (4) Institut d'Astrophysique de Paris, France, (5) Service d'Aéronomie du CNRS/IPSL, Verrières-le-Buisson, France)

To me, the farther out one at the "cold" edge of hab zone sounds like more fun than the one we were discussing earlier.

Last edited: Apr 30, 2007