Centauri System

I'm writing about this because it's the nearest (4.37 light years) star system to our solar system, and it has been a source of science fiction for decades.

The Centauri system consists of three stars that are gravitationally bound. Alpha Centauri is the main star and it's the one that we would be interested in if there is an earth-like planet orbiting it. It turns out that there are at least five known planets orbiting the three stars.

Alpha Centauri A or Cen A is a G2y class star. It's larger (1.227 times) and more (1.519 times) luminous than our sun. It's also an older star with more metal in its spectra. Despite this, Cen A is the nearest match to our sun.

Alpha Centauri B or Cen B is a K1v class star. That makes it a red dwarf. It's smaller (.866) and less luminous (.5) than our sun. Cen A and B have an orbital period around a center point of 79.91 years. The distance between them is about the distance form Earth to Pluto. That means that if you were on a planet orbiting Cen A, you would see two suns.

The third star in this system is called Alpha Centauri C or Proxima Centauri because it's closer (4.24 light years) to our sun than the other two stars. It's a M Ve class dwarf that would be very reddish in color. It's only 0.123 times the mass of our sun, and it's very dim, only putting out 600 times less light than our sun. You could look directly at this star and not be blinded. It would probably appear in the sky of a planet orbiting either Cen A or B.

So far there are six planets orbiting Cen A, Can B and Proxima Centauri. The one around Proxima has only recently been discovered. It's 49% more massive than Earth and although in the habitable zone it's tidally locked to Proxima Centauri. If it has liquid surface water, it would be concentrated around the terminator.

There are two rocky planets around Cen A and three around Cen B. Although these planets could be Earth-like they have eccentric orbits or are either too close to the star or too far away. It remains to be seen if these could have life.

There are three rocky planets around Cen B. they're either too cold or too hot. One of them has a lot of sulfur in its atmosphere, but it is roughly the size of Earth. Again, only time will tell if any of these have life.

My take on this is that the data is too sketchy and presumptive. We need better data to determine if any of these planets would be habitable. That data will be forthcoming.

Thanks for reading.