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Space

Red Dwarfs Could Sterilize Alien Worlds of Life 76

Posted by Unknown Lamer from the not-very-habitable-zone dept.
astroengine (1577233) writes "Red dwarf stars — the most common stars in the galaxy — bathe planets in their habitable zones with potentially deadly stellar winds, a finding that could have significant impacts on the prevalence of life beyond Earth, new research shows. About 70 percent of stars are red dwarfs, or M-type stars, which are cooler and smaller than the sun. Any red dwarf planets suitable for liquid water, therefore, would have to orbit much closer to their parent star than Earth circles the sun. That presents a problem for life — at least life as we know it on Earth, says physicist Ofer Cohen, with the Harvard-Smithsonian Center for Astrophysics. Cohen and colleagues used a computer model based on data from the sun's solar wind — a continuous stream of charged particles that permeates and defines the solar system –- to estimate the space environment around red dwarf stars. 'We find that the conditions are very extreme. If you move planets very close to the star, the force of this flow is very, very strong. Essentially it can strip the atmosphere of the planet unless the planet has a strong magnetic field or a thick atmosphere to start with,' Cohen told Discovery News."
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Red Dwarfs Could Sterilize Alien Worlds of Life More

Red Dwarfs Could Sterilize Alien Worlds of Life

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  • Frist (Score:3)

    by Blaskowicz ( 634489 ) on Tuesday June 03, 2014 @02:12AM (#47152799)

    I learned about that in Slashdot comments, really. Then reading articles on wikipedia, perhaps about specific stars, confirms that red dwarves are quite flare-y. At best the star may be relatively calm but then it will hurl cataclysmic bursts of crap at you anyway.

    • What indigenous life exists on red dwarf? (Score:5, Funny)

      by Cryacin ( 657549 ) on Tuesday June 03, 2014 @02:19AM (#47152817)
      There's a species known as Felis Sapiens that evolved from Lister's cat.

      Unfortunately they're down to one last surviving member due to a religious war based upon the colour of hats that were to be worn. He has no drive to procreate, as he is so perfect, that he is madly in love with himself. Meeeoowww.
    • I don't think that is the only problem with red dwarves. The issue of tidal locking in the "habitable zone" (uhm), e.g., comes immediately to one's mind. The rather unfavorable spectrum doesn't help any either.

      • Re:Frist (Score:4, Interesting)

        by Immerman ( 2627577 ) on Tuesday June 03, 2014 @10:32AM (#47155833)

        At planetary distances tidal locking is a relatively slow process dependent on the angular diameter of the planet as seen from the stellar core and the the magnitude of the gravitational force. Witness Mercury whose day is, after 4+ billion years in close orbit around a relatively massive star, still only 66% as long as its year.

        Actually though tidal locking is not necessarily a problem - atmospheric models suggest that mixing would prevent the temperature imbalance from becoming too extreme. Of course you would end up with several very different ecological niches. Obviously photosynthesis would be impossible on the dark side, but that was a relatively late addition to the game on Earth, and there are plenty of other metabolisms available. Meanwhile the light side wouldn't have to deal with that pesky dark period, and the twilight zone would likely have pretty strong, steady winds from which life could potentially extract energy. Of course that's only relevant after complete locking - but then red dwarfs are essentially immortal, so as long as the planet manages to keeps its atmosphere life should have plenty of time to evolve to the conditions available.

        The biggest problem I see with tidal locking is its potential impact on the magnetic field protecting the atmosphere, as it's believed that Venus and Mars have only tiny magnetic fields in large part because of slow currents in their cores.

        Of course there's also the possibility of the moons of gas giants around red dwarfs. Thanks to the thermal emissions of the gas giant they could be at least a bit further from the sun, as well as getting significant protection from the gas giant's potentially much larger magnetic field. They would also have the benefit of tidally locking to the planet rather than the sun, so they would still experience a diurnal cycle, though it might be a bit slower than Earth's. Io for example orbits Jupiter in 1.7 days.

  • This was quite interesting and comedic for me.. the red dwarfs and the alien world seems interesting to think about!

  • Not deadly forever (Score:5, Informative)

    by mysidia ( 191772 ) on Tuesday June 03, 2014 @02:39AM (#47152895)

    See this article [astrobio.net], on the subject, from back in 2009.

    . Preliminary results from a dedicated research program have shown that planets around red dwarfs could be habitable if they can maintain a magnetic field for a few billion years ...

    The high-energy radiation is predominantly emitted by young stars. As they age, red dwarfs become less magnetically active, while continuing to shine steadily at visible wavelengths for 100 billion years or more. ... ...

    Therefore, if an orbiting planet can just hold onto its atmosphere through the wild early years of its red dwarf roommate, it could end up being a decent place to live.

    • Except... (Score:2)

      by emil ( 695 )

      ...that such a planet would likely be tidally locked, with one side always facing the star. There would be extreme differences of temperature between the night and day sides, and life might only be sustainable in the never-moving twilight region, depending upon atmosphere convection.

      • I think that's oversimplifying things. Models have shown that atmospheric mixing would result in far less extreme temperature differences than you would naively expect. Meanwhile you don't need light for life, photosynthesis is believed to be a relatively late addition to the metabolic game after all, so the dark side could be a thriving ecosystem with chemovores on the bottom, while the light side and twilight region could incorporate photosynthesis as well.

        In fact tidal locking could potentially increas

      • It'd be as hard as finding life in northern scandinavia, where they have months of night and then months of day.

  • Renaming (Score:4, Insightful)

    by bickerdyke ( 670000 ) on Tuesday June 03, 2014 @02:44AM (#47152901)

    Scientists might want to rethink the moniker "habitable zone" if it is filled with a deadly amount of stellar radiation... After all, the very definition of the habitable zone is based on the right amount of energy allow for liquid water reaching the planet...

    • Re:Renaming (Score:5, Interesting)

      by Roger W Moore ( 538166 ) on Tuesday June 03, 2014 @04:31AM (#47153137) Journal

      Scientists might want to rethink the moniker "habitable zone" if it is filled with a deadly amount of stellar radiation...

      The habitable zone only refers to the amount of heat radiation a planet receives it does not mean that every large rock there is habitable - just look at the moon. There are additional constraints for a habitable planet e.g. requires an atmosphere and liquid water. All this result does is to add an additional requirement near a red dwarf: you don't just need a gravitational field large enough to hold onto an atmosphere you also need a magnetic field to shield it.

      • But isn't some radiation shielding not already part of the requirements?

        • Nope, it's literally just the set of orbits where you can have liquid water.

          • I think his meaning was that being a habitable planet necessarily includes a magnetic field strong enough to keep the atmosphere intact.

            • Yeah, if he's pointing out that it's a serious misnomer he's bang on.

              • Re: (Score:2)

                by dryeo ( 100693 )

                Venus does a good job of keeping a heavy atmosphere while only having a negligible magnetic field.
                Thinking about Venus, another big variable is the amount of green house gases affecting the habitable zone and the paradox of the Earth seeming to have been habitable in the sense of having liquid water for close to 4 billion years while the Sun has increased its output by 25%. Of course in another billion or so years the Sun will get hot enough to boil the oceans of Earth and that'll be the end of an inhabitab

        • No. The habitable zone is the range where life (if all other subsequent conditions are met) may potentially exist.

          It strictly means the distance from the star wouldn't burn off all the water or result in a giant ball of ice.

          The rest of the factors are looked at after the habitable zone check, but aren't required for that check.

  • Red Dwarf and radiation (Score:3)

    by Rosco P. Coltrane ( 209368 ) on Tuesday June 03, 2014 @03:17AM (#47152989)

    Isn't it exactly how Rimmer and the entire crew died? Old news...

  • Exactly the same thing would happen to Earth if not for its magnetic field. Red dwarfs doesn't seem special in that regard.
  • If we do find life, it will have evolved in the harshest possible conditions, on a barren irradiated planet beneath a dim red sun. It will be unkillable and probably hungry.
    • Well put.

      Bonus round, though: Life forms rendered by evolution in that environment will likely find fleshy meat-bags distasteful.

    • Yes, any humanoid species that evolved under a red sun would be regarded by us as some sort of "super man" he would likely be faster than a speeding bullet, more powerful than a locomotive, and able to leap tall buildings in a single bound.

  • Newsflash: Being near a giant nuclear furnace is radiation-y.

    Next up: Water is wet, the sky is blue, and Slashdot sucks.

  • ...about greenhouse gases. We are told that high concentrations will make a Venus out of Mars, that in spite of the young sun being substantially "cooler" than the sun is now, the Earth's high GHG concentration over most of the last 600 million years is responsible for it being substantially warmer than it is now, etc. Surely there are atmospheric chemistries that would keep iron-core, magnetic field equipped, water-bearing planets nice and toasty a good safe distance away from a red dwarf. Give the temp

    • Great post. I've been considering the GHG angle for planets too far from their suns for earth-like habitability since the Sunday rendition of Cosmos.

      We've discovered bacteria living inside nuclear reactors here on earth. There is life elsewhere in the universe... it is just statistically unlikely to resemble the flavor we are familiar with.

      IMHO, this life has significantly less chance for evolution to big-brained, universe explorer than we do.

    • The point about the "radiation" from the solar winds isn't the radiation you are thinking of. What they are concerned about is that the solar wind will be so strong that without a powerful magnetic field to redirect it around the planet it will rip the atmosphere from the planet. Have you ever wondered why Mercury doesn't have an atmosphere? It's because the solar wind, with is composed of radiated charged particles, striped it off shortly after the sun and planets formed.

      And as an aside, if it was real rad

      • Fair enough (and yeah, I know about Gamma Ray bursts:-). The Sun could hiccup tomorrow and wipe out most of the life on the planet in an event hardly noticeable from light years away (Larry Niven wrote a lovely short story based on this theme) -- it wouldn't even take a full gamma ray burst. But the point is -- why do they assume that planets orbiting a Red Dwarf will not have a magnetic field? Indeed, I would expect the opposite -- if it has a nickel-iron core like the Earth does, one would expect magn

  • ...wasn't "How can I work in a 'smeghead' joke?", Slashdot might not be the forum for you. I think there's ample openings to post over on TMZ or something.

  • Being small and dim, red dwarf stars exhibit relatively violent flare activity. For example, flares occur regularly on our own star, but the energy this releases is small compared to what is produced in total. However, a flare like that on a star 10.000 times dimmer than ours can momentarily double the energy output. Moreover, flares on red dwarf stars can emit up to 10.000 times as many X-rays as they do on our sun. Oh, and remember that there can be more than one of these flares at a time. So, any life o

  • It would be extraordinarily depressing if our current mindset on life in our galaxy will mimic our early mindset of life in our solar system 100 years ago. We all thought for sure Mars and Venus would have little green men :(

  • 1. Give vasectomies and tubectomies to everyone on alien worlds
    2. ?????
    3. Profit!

  • ...one of the things that is rarely communicated in these sorts of announcements are the error bars in the 'estimate'. Asserting something categorically "is" or "isn't" from what we know is just silly.

    We also believe that we've just discovered terrestrial planets 17x the mass of Earth that, according to our calculations, should be Neptunian "small" gas giants.

    Like so many sciences, the more we discover, the more we realize how very little we know.

    I think it was Carl Sagan who said that - in the context of

  • "potentially deadly"
    "could have significant impacts"
    "a problem for life"
    "estimate"
    "it can strip"
    [...] Cohen told Discovery News

    A lot of 'ifs' and some potential for drama, that's Discovery channel for you nowadays. Everything needs to be spiced up and 'made more interesting' by adding suspense, drame, etc.

    Even a walk in the park can be potential disaster, not to mention the problems that can occur while taking candy from a baby.

    Good thing I have 56 other channels ;)

  • When will the Hollywood or Toho documentary "Godzilla Planet" be made about these amazing discoveries?

  • It's cold outside, there's no kind of atmosphere.... Red Dwarf [youtube.com]

  • Does it make ne extremely low in the Drake equation [wikipedia.org]?

  • This is not new information and I don't know why it's on Slashdot.

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