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posted by cmn32480 on Friday May 27 2016, @08:23AM   Printer-friendly
from the in-star-trek-every-planet-is-habitable dept.

Earlier this month, a team of astronomers from the University of Liège, Belgium, and NASA, using the TRAPPIST instrument at the ESO site in La Silla, Chile, discovered three exoplanets with temperatures similar to those of the Earth and Venus orbiting an ultra-cool M class dwarf star. M dwarves makes up approximately 75 percent of the stars in our galaxy, and this discovery greatly improves the potential for habitable exoplanets.

A recent study from the Imperial College of London, however, suggests that, whilst these planets orbit cooler and less luminous stars, they may still be too hot to be habitable for life as we know it. Dr James Owen, Hubble Fellow and lead author of the study states:

It was previously assumed that planets with masses similar to Earth would be habitable simply because they were in the 'habitable zone'. However, when you consider how these planets evolve over billions of years this assumption turns out not to be true.

The atmospheres of these exoplanets are estimated to make up rougly one percent of their planetary mass. By comparison, the mass of our atmosphere is roughly one millionth of the mass of our planet. This suggests an especially thick atmosphere which, given the resultant greenhouse effect, may render these exoplanets uninhabitable. Naturally, this problem is inherent of planets of Earth-like mass, or heavier; smaller planets, e.g. of Mars-like mass, may lose some of this atmospheric mass through evaporation, as we have observed in our own solar system. Further cataloging of the orbital systems of M class dwarf stars will identify these low mass exoplanets as candidates for the ongoing search for extra-solar life.


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  • (Score: 0, Funny) by Anonymous Coward on Friday May 27 2016, @08:30AM

    by Anonymous Coward on Friday May 27 2016, @08:30AM (#351490)

    Exoplanets were placed in the heavens by GOD to test the faithful, the only Earth is blessed by GOD, and those who forsake the one true Earth shall find themselves ripped apart forever in the super massive black hole of Hell.

  • (Score: 0) by Anonymous Coward on Friday May 27 2016, @08:54AM

    by Anonymous Coward on Friday May 27 2016, @08:54AM (#351493)

    Doesn't this end up increasing the size of the habitable zone?

    • (Score: 2) by b0ru on Friday May 27 2016, @09:12AM

      by b0ru (6054) on Friday May 27 2016, @09:12AM (#351501)

      The earlier study suggests that habitable zones may exist around M class dwarf stars, which increases the set of potentially habitable exoplanets. The latter study, however, posits this set of exoplanets may be diminished by effects of thicker atmospheres e.g. like the planet Venus. The habitable zone pertains to suitability for intelligent life as we know it but, ultimately, so-called 'extremophile' life may survive in far harsher conditions.

      • (Score: 2) by Immerman on Friday May 27 2016, @04:41PM

        by Immerman (3985) on Friday May 27 2016, @04:41PM (#351660)

        I think the point is - if you predict a strong greenhouse effect to be common, then that effectively just moves the habitable zone further from the star. If Mars and Venus were in opposite orbits they would both have far more mild temperatures.

    • (Score: 2) by Immerman on Friday May 27 2016, @05:08PM

      by Immerman (3985) on Friday May 27 2016, @05:08PM (#351676)

      Or at least just pushing it further from the star.

      Having only read the abstract, and done a quick search for "greenhouse", there also seems to be some inconsistency in the paper. Perhaps someone with the patience to read more thoroughly can clarify: The abstract suggests that these planets would have far more massive atmospheres due to a mach larger H/He envelope during formation, which I assume would mean a primarily H/He atmosphere, which I wouldn't think would be a dramatic problem - since neither are greenhouse gasses they would if anything tend to be more opaque to incoming light than to escaping infrared/heat.

      The discussion of greenhouse effect meanwhile seemed to be referencing a predominantly C02/H20/N2 atmosphere, which would seem to be at odds with the initial assumption unless there's some mechanism wherein a H/He atmosphere would encourage the presence of those other compounds. I can't think of any process except perhaps for water, as abundant hydrogen gas would tend to bond with any free oxygen. But even that doesn't necessarily translate to higher levels of atmospheric H20, as the vaporization temperature of water increases rapidly with pressure - for example at 100atm the boiling point of water is about 300C. (and since the freezing point remains roughly the same, that essentially triples the temperature range of liquid water)

      The only mechanism I can think of is that simply by having such a massive atmosphere even very low partial pressures of the gasses would allow for extremely high absolute amounts. But with such dramatic density differences I would think that the atmosphere would tend to stratify, with hydrogen being concentrated in the upper atmosphere, largely shielded from the other volatile gasses by a layer of much denser helium beneath it.

      • (Score: 2) by deimtee on Friday May 27 2016, @06:08PM

        by deimtee (3272) on Friday May 27 2016, @06:08PM (#351709) Journal

        It may be that it narrows the habitable zone. Far enough out, the gases condense on the surface, and the place freezes. Close enough to vaporise and with a thick atmosphere it shoots all the way into Venus greenhouse territory.

        The abstract suggests that these planets would have far more massive atmospheres due to a mach larger H/He envelope during formation, which I assume would mean a primarily H/He atmosphere, which I wouldn't think would be a dramatic problem - since neither are greenhouse gasses they would if anything tend to be more opaque to incoming light than to escaping infrared/heat.

        Pretty much any gas is a greenhouse gas for some spectrum. Isn't a red dwarf likely to have a much higher infrared/visible light ratio anyway?

        --
        If you cough while drinking cheap red wine it really cleans out your sinuses.
  • (Score: 1, Funny) by Anonymous Coward on Friday May 27 2016, @08:58AM

    by Anonymous Coward on Friday May 27 2016, @08:58AM (#351495)

    Have the Founders been found? They're an ocean on a rogue in a nebula somewhere.

  • (Score: 3, Interesting) by khallow on Friday May 27 2016, @09:12AM

    by khallow (3766) Subscriber Badge on Friday May 27 2016, @09:12AM (#351500) Journal
    I wonder why these atmospheres are so massive relative to the planet? Even Venus's atmosphere falls a couple orders of magnitude shy (at one part in ten thousand of the total mass of Venus). There seems to be a fundamental difference in the origins of these systems from our own. A couple of possibilities that come to mind are that the stars, being much smaller and cooler than the Sun, don't do as good a job of pushing away volatile elements like hydrogen or helium. Second, these systems may have started with a much smaller ratio of heavy elements to hydrogen and helium than our system.
    • (Score: 2) by b0ru on Friday May 27 2016, @09:18AM

      by b0ru (6054) on Friday May 27 2016, @09:18AM (#351504)

      I'm inclined to agree that the stellar wind is likely a contributing factor, but the mass of the exoplanets themselves is also important. For example, the comparison of the Earth and Mars; Earth, whilst closer to the Sun, thus, more affected by the solar wind, has managed to maintain an atmosphere partially due to being more massive than Mars, whereas Mars has lost atmosphere through evaporation into space.

      • (Score: 5, Interesting) by jimshatt on Friday May 27 2016, @10:24AM

        by jimshatt (978) on Friday May 27 2016, @10:24AM (#351529) Journal
        Our atmosphere would likely have been blown away by solar wind if we didn't have this awesome magnetic field.
        I don't know if it's possible to look for exoplanets with magnetic field (maybe look for iron in the star it's orbiting)?
        • (Score: 2) by b0ru on Friday May 27 2016, @10:28AM

          by b0ru (6054) on Friday May 27 2016, @10:28AM (#351532)

          Our atmosphere would likely have been blown away by solar wind if we didn't have this awesome magnetic field.

          Absolutely; a magnetic field is certainly a contributing factor, also.

          maybe look for iron in the star it's orbiting

          That'd certainly be a good start.

  • (Score: 0) by Anonymous Coward on Friday May 27 2016, @09:23AM

    by Anonymous Coward on Friday May 27 2016, @09:23AM (#351505)

    via terraforming.

    By the time we have the technology to get there we will have the technology to do this.

    • (Score: 1, Insightful) by Anonymous Coward on Friday May 27 2016, @09:28AM

      by Anonymous Coward on Friday May 27 2016, @09:28AM (#351509)

      We were supposed to have flying cars and genetically engineered transhumans by now, but no, the damn internet just had to be created to distract everyone with porn and social media, so now nobody has the attention span anymore to invent anything new.

      • (Score: 0) by Anonymous Coward on Friday May 27 2016, @09:32AM

        by Anonymous Coward on Friday May 27 2016, @09:32AM (#351512)

        What were we talking about again my gf just had to text me that were out of milk and the cat puked.

        • (Score: 2) by GreatAuntAnesthesia on Friday May 27 2016, @11:53AM

          by GreatAuntAnesthesia (3275) on Friday May 27 2016, @11:53AM (#351558) Journal

          Lol, pls post cat pix.

          • (Score: 2, Funny) by tractatus_techno_philosophicus on Friday May 27 2016, @01:10PM

            by tractatus_techno_philosophicus (6130) on Friday May 27 2016, @01:10PM (#351576)

            Suddenly, a fabulous cat appears.

            (_\ヽ
              \\ .Λ_Λ.
               \( ˇωˇ) 
                > ⌒ヽ
               /   へ\
               /  / \\
               レ ノ   ヽ_つ
              / /
              / /|
             ( (ヽ
             | |、\
             | 丿 \ ⌒)
             | |  ) /
            `ノ )   Lノ
            (_/

            --
            No moral system can rest solely on authority. ~A.J. Ayer
            • (Score: 0) by Anonymous Coward on Friday May 27 2016, @01:16PM

              by Anonymous Coward on Friday May 27 2016, @01:16PM (#351577)

              if my cat strutted like that after puking, I would throw it out of the house.

            • (Score: 0) by Anonymous Coward on Friday May 27 2016, @09:37PM

              by Anonymous Coward on Friday May 27 2016, @09:37PM (#351778)

              ... are you sure that's not a fabulous pig?

  • (Score: 2) by HiThere on Friday May 27 2016, @07:20PM

    by HiThere (866) Subscriber Badge on Friday May 27 2016, @07:20PM (#351738) Journal

    I believe they aren't even measuring all the factors that need to go into making a planet "habitable", although I'm more talking about generating native life than people living on it.

    E.g., I think it quite likely that a very large moon is necessary. It stabilizes the orbital inclination to the planet doesn't "tumble" (think gyroscope). There are also arguments about tides being necessary, but I haven't been able to decide about those.

    OTOH, it's also possible that they are ignoring entire classes of habitable planets. E.g., it seems to me quite plausible that moons of giant planets could be habitable. Jupiter's moons are dubious because of it's strong magnetic fields (but perhaps life could evolve to handle that?), but IIUC equivalent moons of Saturn would be quite habitable if they were warm enough. And perhaps a methane based life exists on Titan.

    Class M dwarfs tend to have strong flares, so they may be unlikely. (The planet needs to be pretty close to them to be habitable. It's been suggested, however, that class K dwarfs are reasonable. (The sun is a class G dwarf. (M are red, K are orange, G are yellow.) Probably only the K, M, and G dwarfs are stable for long enough to devlope life, but that's most stars in the galaxy. Unfortunately, M is the most common.

    Now if native life has developed, it's likely to be a very inhospitable place to land. Massive allergy attacks. But if life hasn't developed there isn't likely to be much oxygen in the atmosphere.

    All-in-all I think macro-life is the best approach to take.

    --
    Javascript is what you use to allow unknown third parties to run software you have no idea about on your computer.