MadSci Network: Astronomy

Re: what is the age of the star proxima centauri?

Date: Sat May 19 12:55:18 2001
Posted By: Irene Little, Faculty, CASA, University of Colorado
Area of science: Astronomy
ID: 989808457.As

It is difficult to determine the age of an individual star. However, alpha Centauri Proxima appears to be the closest member to the Sun of the alpha Centauri triple system. That means that Proxima very likely formed at the same time as the main pair (alpha Cen A + B). Alpha Cen Proxima is at a distance of about 4 lightyears. Alpha Cen A is very similar to the Sun in composition, hence astronomers estimate that it has the same age as the sun (maybe a wee bit older).
Age = 6 +\-1 billion years for alpha Centauri Proxima.

References: I asked an astronomer friend, Thomas Ayres, who is an expert on alpha Centauri.

[For those not familiar with the +/- notation, that is the way scientists express their confidence in a result. The current best estimate for the age of the stars of alpha Cen is 6 billion years. However, various uncertainties in the distance, mass, composition, stellar models, etc. mean that our estimate of its age is also uncertain. In this case, alpha Cen Proxima could be 5 billion years or 7 billion years old and still easily meet all of our constraints from the various measurements. With somewhat less likelihood, alpha Cen Proxima could be 4 billion years or 8 billion years old. With even less likelihood, but not implausibly, alpha Cen Proxima could be 3 billion or 9 billion years old. Moderator.]

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