View Full Version here: : Exo-planets Ranked by Habitability
13-12-2011, 08:34 PM
Here ya go .. one for the eternally hopeful ...
HEC: Potential Habitable Worlds Ranked by Surface Habitability (http://phl.upr.edu/projects/habitable-exoplanets-catalog/list_hab)
Mostly contains unconfirmed Kepler candidates.
Notice the distance from Earth figures.
Remote detection of life at these distances ???
I seriously doubt it !
Have fun ..
13-12-2011, 10:44 PM
Despite those distances, they do have spectroscopes that have the necessary resolution to be able to detect possible life processes (e.g. photosynthesis). But they'll still not be 100% sure. The only way to do that is to go there....something that will have to wait until we figure out how to.
Mind you, that is a good site. Lots of other stuff to look at and download (software etc).
14-12-2011, 08:00 AM
There's a need to be 100% clear about the fact that the idea of remote spectroscopic detection of distant exo-life from Earth's vicinity, results in 100% inference.
It will remain this way until there's a direct correlation established between a verified exo-life discovery, and the verified Habitable Zone parameters in which it is discovered.
Direct spectroscopic detection of HZ Earth-like atmospheric exo-planet gases, from 1000s of Lightyears distant, has not yet been accomplished. JWST is the only instrument I'm aware of that will be capable of directly detecting the atmospheric composition of only the closest exo-planets (presently ~20 Lyrs, or so) .. and this remains to be verified.
14-12-2011, 11:39 AM
My above statement has spurred me on to check my updatedness, and I find a recently released (Nov 2011) paper (http://arxiv.org/abs/1104.0570) which claims confirmed detection of a strong 3.3 micron feature, (corresponding to the methane v3 branch) in remote detection of the atmosphere of HD 189733b (a hot Jupiter ~63 Lyrs distant).
The detection was done with the Spex spectrograph at the NASA Infrared Telescope Facility atop Mauna Kea.
As far as observing Habitable Super-Earth atmospheres, the main issue here is their small size, low temperature and their relatively large separation from their star. In principle, it appears they can be observed at low resolution in the Mid-IR, provided their hosting star is a bright M dwarf. While most of the Sunís neighbourhood is composed of these late-type stars, dedicated technology is needed to increase the numbers of known instances. The 2MASS catalogue sample and space-bound WISE and GAIA programs are targetting at this goal over the next five years.
15-12-2011, 01:35 PM
It's all inference, as is all of science. All observations need to be examined and checked out, yet you can never be 100% certain that what you say is correct.
I said the spectroscopes have the necessary capabilities to do the job. I said nothing about the instruments needed to accomplish the detection:). No matter if the spectroscope attached to the telescope has the capability to detect the signs of life on a planet, if the scope it's attached to can't resolve the target, then it's an exercise in futility even trying. In order to resolve a planet from several hundred to a few thousand light years away to the point you could accomplish the detection, you'd need a space telescope with a mirror several hundred meters across. To image it directly and see surface features, you need one a kilometre across. I think it'll be a little while before we get to that stage!!!! :)
Oh...BTW, they have detected the atmospheric compositions (or partial compositions, thereof) of planets from other stars systems several tens to hundreds of light years away using instruments such as Hubble and Keck and the appropriate spectroscopes. But it's not an easy task. However, as to what percentages of gases are present, and their origins etc etc etc, are, that is a bit beyond them at present. What's more, those detection have only been accomplished for Hot Jupiters, nothing else.
15-12-2011, 01:52 PM
GAIA will have the best chance of accomplishing the task as it's been designed to be super accurate in both its positional and detection capabilities.
The detection of the methane in HD189733b's atmosphere could be accounted for by the presence of iron and carbon particulate suspension in the atmosphere of the planet. It's much like the industrial process of producing methane....cook up water at high temps in the presence of iron and carbon, you get methane. The iron acts as a catalyst for the reaction. It's probably what's going on in the planet's atmosphere.
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