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What is the Age of Kapteyn’s Star?

-- | April 19, 2015

Question: I’m interested in Kapteyn’s Star. July 2014 popular news reports about the discovery of Kapteyn b & c mentioned an age for the system of 11.5 GY. However, the EU exoplanet database lists an age of 8 GY. (For some reason, it also lists a few stars with ages older than 13.8 GY.) Can you provide a definitive age? Kotoneva’s quite thorough 2005 study of the star did not provide an age; the authors did use a 10 GY estimate for temperature purposes. My guess is that the EU had an old list of stellar characteristics, and when someone finds a planet, they tack the new planet info onto the old star info. Did something happen to change the dating of Kapteyn? Thanks for your help. — Andrew

Answer: I am not sure what database the “EU exoplanet database” is, but I have reviewed a recent analysis by Anglada-Escude etal. (2014) which includes a nice description of the limitations associated with determining the age of Kapteyn’s Star. Anglada-Escude etal. (2014) list the age as greater than 10.0 GY, but less than 13.8 GY (the upper limit set by the current value for the age of the universe). I believe that this is the best current estimate for the age of Kapteyn’s Star.

Jeff Mangum

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