Do you think life can form around around M-class Stars?

[TheSealBrigade]

I believe that life can form around red dwarfs, but what do you think?

[Tex Mechs Robot]

possibly. but it seems that the habitable zone around such a star would be so close that the planet would be tidally locked. there would be regions that stretched between the poles at 90 degrees from the star on each side that would be the average temperature. life on the far side would have to thrive in extreme cold while life on the near side would have to thrive in extreme heat. light and darkness would also play a factor in the development on the life. it would be an interesting ecosystem to say the least.

[Red Iron Crown]

Sciencey question moved over to Science & Spaceflight.  

[Spaceception]

35 minutes ago, saurodye said:

I believe that life can form around red dwarfs, but what do you think?

1: Threads like these should be in Sci/Spaceflight, don't worry, I reported it, and it should be moved shortly

2: Yes, most red dwarfs should be able to have life-supporting planets as long as they're not too active (Big flares), and if they're Large (Like Lalande 21185), although, smaller stars like Proxima should be able to have life-supporting planets if they're old (And hence not as active), but the chance of being tidally locked goes up hugely.

EIDT: Hey, it was moved, that was quick.

Edited February 26, 2016 by Spaceception

[kerbiloid]

The thermodynamical equilibrium inside a normal star (like the Sun) is guaranteed by radiative transfer, while in red dwarves - by the convectional transfer.
As a result, a red dwarf is a big lava-lamp with continuously varying luminosity,
So, if the planet is not covered by a thick atmosphere like Venus, its surface temperature would be unpredictable and unstable, too. Also this would cause unpredictable hurricanes.

[Spaceception]

16 minutes ago, Tex Mechs Robot said:

possibly. but it seems that the habitable zone around such a star would be so close that the planet would be tidally locked. there would be regions that stretched between the poles at 90 degrees from the star on each side that would be the average temperature. life on the far side would have to thrive in extreme cold while life on the near side would have to thrive in extreme heat. light and darkness would also play a factor in the development on the life. it would be an interesting ecosystem to say the least.

That's very true, although if the planet in question has an atmosphere about as thick as Earths, the planet could rotate (Slowly) and have a day/night cycle of a couple days/weeks, if the planet has a large enough moon, that could help it rotate faster, and if the planet orbits a large M-dwarf, (Like Lalande 21185) the longer orbital period (40-120 days) could give it a larger chance of having a day/night cycle like Earths.

[Kertech]

If the planet did have an atmostphere but was tidally locked you'd get some interesting weather patterns. Interesting as in a continuous cycle of wind from the day side to the night side and back. Life on this sort of planet would have to deal with hurricane strength winds permanently along with radiation and temperature extremes...

[p1t1o]

Problem with this concept is how we define "life". We always look for the "goldilocks" zone so we have liquid water, but if we are looking for life, and not necessarily for another home for ourselves, we aren't really restricted to those conditions.

We havn't found any other life so its hard to say what it would look like, but for illustration, there are strong things going for an amonia-based life cycle, which necessitate an entirely different temperature range, ergo, different planetary distances etc.

As long as the surface of the planet is recieving enough energy, I'd say its hard to rule out anything at this point.

[magnemoe]

3 hours ago, Spaceception said:

That's very true, although if the planet in question has an atmosphere about as thick as Earths, the planet could rotate (Slowly) and have a day/night cycle of a couple days/weeks, if the planet has a large enough moon, that could help it rotate faster, and if the planet orbits a large M-dwarf, (Like Lalande 21185) the longer orbital period (40-120 days) could give it a larger chance of having a day/night cycle like Earths.

If the planet is able to keep an elliptical orbit a bit more elliptical than the moon have around earth the sun will move forward an back on the sky. 
You also need plenty of water as much will freeze on the shadow side, you also want oceans close to that part to bring in heat, an thick atmosphere will help a lot, you don't want co2 to freeze out. 

Slow rotation might not be good as everything will freeze over during the night, again an thick enough atmosphere might help. 

Double planets of moons of gas giants are safe from this. 

 

[fredinno]

4 hours ago, Tex Mechs Robot said:

possibly. but it seems that the habitable zone around such a star would be so close that the planet would be tidally locked. there would be regions that stretched between the poles at 90 degrees from the star on each side that would be the average temperature. life on the far side would have to thrive in extreme cold while life on the near side would have to thrive in extreme heat. light and darkness would also play a factor in the development on the life. it would be an interesting ecosystem to say the least.

The near side should be fine, if Earth was tidally locked, it's back side would be -30*C. Life is possible, more complex life is going to be more difficult, but it's possible all right. A better question is if brown dwarfs can sustain a habitable planet for long enough for life to develop....

4 hours ago, Spaceception said:

That's very true, although if the planet in question has an atmosphere about as thick as Earths, the planet could rotate (Slowly) and have a day/night cycle of a couple days/weeks, if the planet has a large enough moon, that could help it rotate faster, and if the planet orbits a large M-dwarf, (Like Lalande 21185) the longer orbital period (40-120 days) could give it a larger chance of having a day/night cycle like Earths.

Yeah, tidally locked planets technically rotate.

[Tex Mechs Robot]

15 minutes ago, fredinno said:

Yeah, tidally locked planets technically rotate.

yep. at a rate of exactly one revolution per revolution around their parent body.

[insert_name]

It would be interesting to see life on a planet battered by hurricane strength winds. maybe bouyant airborne drifters? that would be so cool

[cubinator]

I think it's certainly possible. The big problem identified with red dwarfs is that their "habitable zone", the area in which liquid water can form, may be too close to be safe for life as we know it. I personally think the term "habitable zone" is misleading, because there are plenty of places in our own solar system that are way farther out than that region that could potentially support some form of life, such as Europa and Enceladus, which orbit gas giants far out, and have liquid water mantles, and Titan, which has methane lakes, a thick atmosphere, and rain, which combined make it a good candidate for at least microbial life. There could be a planet orbiting a red dwarf far from it's so-called "habitable zone", which has a moon close enough that the tidal forces heat it inside, causing sulfur-rich volcanic vents to open which could very well provide food for chemosynthetic organisms.

[Scotius]

The sheer number of red dwarfs in our Galaxy alone, practically guarantees some of them will have "habitable" planets. Will life form there? Good question.

[fredinno]

1 hour ago, insert_name said:

It would be interesting to see life on a planet battered by hurricane strength winds. maybe bouyant airborne drifters? that would be so cool

You basically described Venus- Venus is thought to have a good chance of having life in its clouds in the form of bacteria.

[daniel l.]

It depends on the class. An M2 for example should do fine. But an M9 would be too small, cold, and dense to support such a world as the habitable zone would end up inside the Roche limit.

Edited February 26, 2016 by daniel l.

[Bill Phil]

Even with tidal locking it's possible that the temperature could be equalized.

But there are other problems. Gas giants, as we know them, aren't as likely to form around red dwarves. But even if one did, a habitable moon would be pulled away if it's in the habitable zone.

Farther away, though... If a gas giant formed, microscopic life from tidal heating could form, like it could be with Europa/Enceladus.

[Spaceception]

14 hours ago, Bill Phil said:

But there are other problems. Gas giants, as we know them, aren't as likely to form around red dwarves. But even if one did, a habitable moon would be pulled away if it's in the habitable zone.

Yeah, I've tried that in US2, doesn't work

[fredinno]

17 hours ago, Bill Phil said:

Even with tidal locking it's possible that the temperature could be equalized.

But there are other problems. Gas giants, as we know them, aren't as likely to form around red dwarves. But even if one did, a habitable moon would be pulled away if it's in the habitable zone.

Farther away, though... If a gas giant formed, microscopic life from tidal heating could form, like it could be with Europa/Enceladus.

Well, Ice giants are pretty common around red dwarfs due to the lower gas levels available- in the habitable zone, they have enough volatiles to host airborne life. Its moons would likely be smaller- HOWEVER, a large moon suddenly being captured or forming due to collisions is not unprecedented. Earth, Saturn, and Neptune all experienced this.

[Spaceception]

20 hours ago, daniel l. said:

But an M9 would be too small, cold, and dense to support such a world as the habitable zone would end up inside the Roche limit.

Really?

[Bill Phil]

55 minutes ago, Spaceception said:

Really?

It depends on the habitable planet's size, too.

[daniel l.]

3 hours ago, Spaceception said:

Really?

Yes, M9's put out so little light and heat that it would make earthlike planets impossible. Because in order to maintain fusion: such a star 10 or more Jupiter masses would be compacted by gravity into a radius smaller than Jupiter. This would make the gravity well very steep, and because of how little radiation is put out: the habitable would be inside the Roche limit.

 

What's ironic however is that a large brown dwarf actually puts out more heat than an M9 red dwarf, So its actually possible to have a life sustaining planet around a brown dwarf.

[Spaceception]

Just now, daniel l. said:

Yes, M9's put out so little light and heat that it would make earthlike planets impossible. Because in order to maintain fusion: such a star 10 or more Jupiter masses would be compacted by gravity into a radius smaller than Jupiter. This would make the gravity well very steep, and because of how little radiation is put out: the habitable would be inside the Roche limit.

 

What's ironic however is that a large brown dwarf actually puts out more heat than an M9 red dwarf, So its actually possible to have a life sustaining planet around a brown dwarf.

Hmm, That's interesting.

[YNM]

AFAIK Class M9 aren't red dwarfs anymore... But dunno about recent changes made by some tiny stars.

For OP question : The problem, to say, for red dwarfs is that they put out little heat. Most of the light output will be in infrared with almost none at the higher ends - depends on how you see it, it can be an advantage or a problem, as UV and X-ray are limited (less cell damage) but so are visual light (take photosynthesis - high frequency lights are needed to break water), probably life there could thrive on these lower wavelengths light. Also, planets will be hugging the star, which means tidal locking, and something worser - these tiny stars can produce flares _magnitudes_ above Sun's flares. Which means the life there, while used to low-energy light, suddenly will receive higher-end light and additional particle radiation. Such a great place to have thrilling life, huh ?

 

 

 

[Bill Phil]

Are we not going to bring up the extended habitable zone? The Sun's goes as far as Ceres, if only it was massive enough to have an atmosphere without human intervention.

Also, what's the average metallicity of M stars?

Edited February 28, 2016 by Bill Phil