What if 8 closest stars to Earth all have planets?

[Battlehymn Republic]

I'm writing a story and a plot element is that the closest 8 stars to Earth/Solar System all have planets capable of being terraformed.

Is that too improbable?

[Hotfoot]

Having planets? Just fine. We're finding more and more planets in other star systems all the time.

Having Earth-type planets in respective green zones? *tilts hand back and forth* Not so good, but not something people are going to tend to jump all over you for.

[wolveraptor]

Well, they don't really need to be earth-like if they're being terraformed anyways. They just need to be around the same size range as earth (unless your scenario involves uber-technology that can actually add significant mass toa planet). In which case, you might find that some of them are moons to a large gaseous planet or something.

[Battlehymn Republic]

Well, they don't really need to be earth-like if they're being terraformed anyways. They just need to be around the same size range as earth (unless your scenario involves uber-technology that can actually add significant mass toa planet). In which case, you might find that some of them are moons to a large gaseous planet or something.

Easily terraformed is what I was going for. You know, Mars-like, or better.

[drachefly]

Well, let's see what the nearest 8 stars are:

+http://cassfos02.ucsd.edu/public/nearest.html
(high magnitude number -> smaller, dimmer star)

Code: Select all

Name                            Distance        Apparant        Absolute
                                (lightyears)    Magnitude       Magnitude
                                                                
Sun                             0.00001         -26.8           4.75     
Proxima CentauriAlpha Cen C     4.3             ?check          15.5
Rigil Kentaurus Alpha Cen A     4.3             -0.1            4.3
Alpha Centauri B                4.3             1.5             5.8
Barnard's Star                  5.9             9.5             13.2
Wolf 359                        7.6             13.5            16.8
Lalande 21185                   8.1             7.5             10.4
Sirius A        Alpha CMa A     8.6             -1.5            1.4
Sirius B                        8.6             7.2             11.5

So, of the nearest 8,

Wolf 359 and Proxima Centauri are freaking dim
Barnard's star, Lalande 21185, and Sirius B are quite dim

Sirius A is REALLY INTENSE.

That leaves 2 sunlike stars.

Now, as for Sirius, since it's heavier it could have lots of planets, and since its green zone is much larger, there could be several planets there, not just one. But it would have more ionizing radiation.


The big worry is the little stars. They could attract less matter and get fewer planets (or lots of really little ones too small for an atmosphere).

On the other hand, we have two planets in the green zone in this system (Mars would be OK if it were heavy enough to hold on to more of its greenhouse gases), so having one such planet in the smaller green zone of a littler star would be sensible. Might not be ideal... might need to have atmosphere dumped on it occasionally if it's too light to hold on by itself...

[GrandMasterTerwynn]

I'm writing a story and a plot element is that the closest 8 stars to Earth/Solar System all have planets capable of being terraformed.

Is that too improbable?

Yep. One of your eight systems is Sirius, which is comprised of an hot (A-class) Main Sequence star and a white dwarf. Sirius is 250 million years old, and any planets in its habitable zone would either still be forming, or else, would have been ejected or toasted by Sirius B, which used to be a B-class blue giant which lived until about 125 million years ago (half of Sirius's lifespan to date.)

Another of your eight systems is Alpha Centauri, which could actually support habitable planets around A and B.

Another of your eight systems is Barnard's Star, which is eleven to twelve billion years old. Which is to say it formed before the galaxy was really enriched with heavy elements. This tends to limit the possible formation of terrestrial planets around it.

The rest of the eight nearest stars are red dwarves. All of them are flare stars. A planet would have to form close enough to be tidally locked with the star in order to be habitable . . . which, while it is possible, would be an experience which would be thoroughly alien to humans, though it could make for interesting writing.

In short, only one of the eight systems could produce planets that would be recognizeably Earth-like, two of them won't have planets worth mentioning, and the remaining five would be thoroughly alien to us.

[Battlehymn Republic]

Okay, then this leads to a follow-up:

Of all the stars that have a probably chance of having Mars-like, or terraform-likely planets, which are the 8 closest ones to Earth?

[GrandMasterTerwynn]

Okay, then this leads to a follow-up:

Of all the stars that have a probably chance of having Mars-like, or terraform-likely planets, which are the 8 closest ones to Earth?

A catalog of especially Sunlike stars.

[SyntaxVorlon]

You'd be better of saying that the starsystems with non-Sol stars would have space stations, large scale orbital habitats, asteroid mining etc at ranges that would be livable, instead of terraformed planets.

[drachefly]

Oh, right... Sirius being pretty young, whether it even has planets depends on how rapidly planets form... which we don't know.

[drachefly]

(Ghetto edit:) that was meant to agree with GrandMasterTerwyn, but also allow as how we can't be utterly sure.

Also, good point about the stars too old to have planets.