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Tidal Heating Shrinks Goldilocks Zone Around Red Dwarfs
scibri writes "An overlooked factor could shrink the habitable zone for planets around M-class dwarf stars by as much as 50%. For these smaller, cooler stars, the habitable zone was thought to extend to relatively close orbits. But as you get closer to a star, the tidal force it exerts on a planet increases. Since planets do not have perfectly circular orbits, tidal forces cause the planet to flex and unflex each time it moves closer to or further from its star; kneading its interior to produce massive quantities of frictional heat — enough to scour the planet of any liquid water. Because M-class dwarf stars are the most numerous in the galaxy, and close-in planets are easier to spot than more distant ones, such stars have been a major target for planet hunters seeking Earth-like worlds. But now it seems we may have been looking in the wrong place for Earth's twin."
Earths twin would be a planet of the same size, orbiting a star of the same size and characteristics, in the same way.
I think you mean "planets that may have water".
Friction is hell
In space or on face
Sudsy blade orbits
Don't leave a trace
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What about moons around large planets? Similar, no?
Funny, I don't remember that one.
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That smeghead makes everything around Red Dwarf uninhabitable.
I am officially gone from
Goldilocks didn't have any dwarfs! Geez...
Could someone please explain this to me?
In TFA they say that people looking for Exo-planets are looking for ones with close orbits. They believe now that because of tidal forces those planets would have hotter temps and not be candidates for a Earth-like planet.
Looking for close orbit planets is a fine way to find exoplanets.
What they should say is that looking for close orbit planets is not a good way to find earthlike planets with liquid water.
Now take in your head the originally believed habitable zone, you are going to have to shorten that on the side closer to the star. One would not necessarily extend that zone an equal distance away from the star as planets not in close orbits won't get the extra heating.
Io and Callisto are the same distance from the Sun, but Io is a _lot_ hotter. If you get far enough from a red dwarf sun to be too cold, the tides are a lot weaker.
I would have assumed that tidal locking would eventually cause more trouble for life than tidal heating does good.
Ezekiel 23:20
"But now it seems we may have been looking in the wrong place for Earth's twin."
Why do people feel compelled to say things like this? There are multiple reasons why we will continue to be motivated to identify planets orbiting M-class stars. The most compelling is perhaps that we simply don't yet know the full range of potential planetary scenarios, both the types of orbits they might adopt and the material nature of the planets themselves. We can't yet even anticipate the full range of unique conditions that might make a planet habitable (for humans much less otherwise). The more planets we identify and characterize, the better we get at estimating those full ranges. So just because these M-class planets are less likely to be a home-away-from-home is not a very good reason to stop looking for them altogether.
Researcher was probably reading Neutron Star and went 'Oh, Crap!'
The article fails to mention that although the habitable zone would shrink closer to the sun, it would expand further from the sun. Tidal forces obey a power law, so this expansion on the far side would not be as great as the area lost on the near side, but it does open up some interesting possibilities, such as having a dark, warm planet.
Worst Disney Mashup ever.
If you are not allowed to question your government then the government has answered your question.
Even if the environmental changes from tidal locking wiped out most advanced lifeforms plenty of microbes and extremophiles would almost certainly survive. Since dwarf stars have a MUCH longer lifespan than larger stars there would be likely be plenty of time for more advanced life to evolve multiple times over.
As for winds and weather, I imagine they would actually be (relatively) mild near the day/night poles, but strong and steady near the twilight ring, with cold,dry air flowing dayward at the surface and hot, wet air flowing nightward at high altitude. Storms would likely be severe and virtually continuous, but since the system is in dynamic equilibrium less volatile than on Earth, which has Bernoulli forces and a daily heating cycle constantly churning things up.
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They compare to Jupiter's moon Io in the article, whose proximity causes tidal heating and makes it the most geologically active body in the solar system. However, all the energy that goes in to tidal heating is drawn from its orbital energy and would normally cause the orbit to circularize (tidal dissipation), thus eliminating the heating - the only reason that doesn't happen with Io is because it's locked in a 1:2:4 orbital resonance with Europa and Ganymede, both of which have much greater orbital energies.
Now I imagine this would take longer with a planetary-sized orbit than with a moon-sized orbit, but unless the planet migrated inwards considerably I would expect that it would have largely occurred while the proto-planetary cloud was still coalescing. It might contribute to a longer cooling period, but I don't see how that's really a problem, it's not like a lot of these dwarf stars aren't considerably older than Sol, even a few billion extra years years of cooling would still give life there a head start on us. In fact, considering that Earths volcanic phase is when life here got it's start, a mechanism that might have extended that period seems like it could make life even more likely.
--- Most topics have many sides worth arguing, allow me to take one opposite you.