Rocky planets around red dwarfs

[virgil1612]

Hello,

1. Does the star type influence the type of planets forming around it? Specifically, could a red dwarf favour the formation of rocky planets around them, compared to gas giants?
2. Planets would be much closer to a red dwarf star than they are for a solar type star. Consequently, the radiations (stellar wind, UV) would, I presume, be much stronger than for Earth. Can we even conceive the possibility for life in such conditions, even inside the habitable zone?

Thanks for your insight,
Virgil.

 

[Comeback City]

Here is my logic...
Red dwarfs have relatively low mass, and thus can only hold planets in their orbit when the planets are relatively close to the star. Since they are closer to to the star, they will be more susceptible to solar winds. This would be a problem for life to form. Also, if complex life were to form, it would most likely have to develop heat sensing organs (in the place of eyes).
As for types of planets, I'm not entirely sure. I would think they would be mostly rocky planets but don't have much logic to back it up (without google ). Maybe since they are closer to the sun, the solar winds would be more likely to blow away gaseous atmosphere.

 

[nikkkom]

Consequently, the radiations (stellar wind, UV) would, I presume, be much stronger than for Earth. Can we even conceive the possibility for life in such conditions, even inside the habitable zone?

Higher radiation is not that big problem.

First, more atmosphere protects better. Say, a version of Earth but with 3 atm surface pressure (three times more massive atmosphere).

Second, evolution does not prefer the best possible resistance to radiation in living beings. Evolution _needs_ mutations to happen, it only needs to make sure that radiation damage is not causing organisms to not survive until they have offspring. It's quite likely that life in more radioactive environments will simply have enhanced mechanisms to repair that damage.

In Three Mile reactor cleanup effort, one of the difficulties encountered was the growth of cyanobacteria in the water. *In the reactor vessel*, whose walls were emitting several thousands roentgen per hour.

 

[Comeback City]

@nikkkom that is very true. One thing that comes to mind, though... is there anything that prevents liquid water from collecting on these planets (i.e. the higher radiation)?

Also what do you think about the planet situation (rocky vs gaseous)?

 

[virgil1612]

I was thinking about red dwarfs possibly favouring rocky planet formation because of the recent discovery of the Trappist system... A red dwarf surrounded by 7 (!) rocky planets... seems quite extraordinary.