Most earthlike exoplanet yet (ESO team 23 April)

[marcus]

http://www.france24.com/france24Public/en/news/world/20070422-Astronomy-red-dwarf-mother-earth.html

this item first appeared in the Malaysia Sun AFAIK

 

[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/

PARIS, April 24, 2007 (AFP) - Astronomers reported on Wednesday they had discovered a "super-Earth" more than 20 light years away that is the most intriguing world found so far in the search for extraterrestrial life.

 

[neutrino]

Alright, it seems to official now. :)
http://www.space.com/scienceastronomy/070424_hab_exoplanet.html

 

[baywax]

Alright, it seems to official now. :)
http://www.space.com/scienceastronomy/070424_hab_exoplanet.html

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.

 

[OSalcido]

Besides having the right temperature, the new planet is probably full of liquid water, hypothesizes Stephane Udry, the discovery team's lead author and another Geneva astronomer

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?

 

[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!

 

[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"..

 

[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.

 

[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

 

[Astronuc]

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?

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.

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.

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.

 

[dimensionless]

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

 

[matt.o]

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

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.

 

[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!

 

[Garth]

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.

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

 

[Garth]

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!

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?.

The field of extrasolar planets has rapidly expanded to include the detection of planets with masses smaller than that of Uranus. Many of these are expected to have little or no hydrogen and helium gas and we might find Earth analogs among them. In this paper we describe our detailed interior models for a rich variety of such massive terrestrial and ocean planets in the 1-to-10 earth-mass range (super-Earths). The grid presented here allows the characterization of the bulk composition of super-Earths detected in transit and with a measured mass. We show that, on average, planet radius measurements to better than 5%, combined with mass measurements to better than 10% would permit us to distinguish between an icy or rocky composition. This is due to the fact that there is a maximum radius a rocky terrestrial planet may achieve for a given mass. Any value of the radius above this maximum terrestrial radius implies that the planet contains a large (> 10%) amount of water (ocean planet).

Fancy a swim anybody?

Garth

 

[baywax]

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!

Hello Wallace...

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

THE INFRARED SPECTRUM OF EXOPLANETS
M. Ollivier
Institut d’Astrophysique Spatiale - Université de Paris-Sud (marc.ollivier@ias.u-psud.fr)

At a time where a program of space mission dedicated to the direct detection and spectral analysis of extrasolar planets is under development both at ESA and NASA
(Darwin/TPF), the choice of the observation spectral window is still not completely clear between near and thermal infrared. In this paper, I review the question of infrared spectrum of both giant and telluric exoplanets, in these two spectral windows. Particularly, I focus on the information the continuum and the spectral features can provide, in term of size and temperature of the planet, composition and depth of its atmosphere. I show that spectra in the thermal infrared (between 6 and 20 microns) at
a typical spectral resolution of 20 to 50 are sufficient to determine roughly the nature of the atmosphere (reducing or oxidizing) and its major components. As a conclusion, I show that thermal infrared is also suited to identify molecular species that can be used as bio-tracers in the atmosphere of telluric extrasolar planets.

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.

 

[baywax]

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

EXOPLANETS:
a picture at last?
For the first time, an international team has apparently managed to photograph a planet in orbit around a star other than our Sun. But until their initial results are confirmed by other observations, the researchers are remaining very cautious...

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

Planet in view?
Then in April 2004, the researchers observed a very cold and very faint body near to brown dwarf 2M1207, only just perceptible through the telescope’s infrared camera. Spectral analysis, carried out with great difficulty because of the object’s low luminosity, showed that it held water! The body was provisionally named GPCC, “Giant Planet Candidate Companion”…

Sorry, just another quote from the same page.

 

[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.