Expert: Philip Stahl - 5/12/2004

Question
How would you describe the star "proxima centuri" and how does it compare with our sun?  Is proxima centuri in our galaxy or another galaxy?  Is it not the next closest star to our sun?  Do all stars go through a life cycle or some process of development, apex, then death phase?

Answer
Hello.

Proxima Centauri is a red dwarf companion to Alpha Centauri, smaller than the Sun, less massive and cooler. (The Sun and Alpha, meanwhile, are nearly physical "twins")

At a distance of about 1.3 parsecs (4.3 Light years) it's also well within the confines of our galaxy.

Most astronomers believe Proxima is actually a tad closer than Alpha, say around 4.22 LY distant, compared to 4.3 LY.

Yes, all stars go through "life cycles" which vary according to their starting mass. The more initial mass a star has, the stronger its gravity, and the brighter and hotter it will burn. Thus, since the energy conversion rate is faster, more massive stars burn out sooner.

As you can see the particular process will differ for each star, depending on the starting mass. In addition, the most massive stars will not end their lives "quietly" but rather in enormous explosions we call "super novae".

At the end of this, either a super dense neutron star, or a black hole will remain.

To reach this limit of a violent end, leading to neutron star or black hole, it is believed that the starting mass for a star must be at least twice that of the Sun. (A lot more to attain black hole status at its end).

The Sun, as implied here, will end its life somewhat quietly, after it first expands to the "Red Giant" stage - following all its hydrogen consumption some five billion years hence.

After that stage, it will become a white dwarf, very compact and far dimmer than it is now.