STELLAR SURFACE GRAVITY FROM THE TIME SCALES OF THE BRIGHTNESS VARIATION

Recently, some authors (Kallinger et al. 2016) proposed a new method to derive the stars' surface gravity "g". This parameter is fundamental to derive the mass and radius of the star itself. Mass and radius, in turn, are essential quantity for a correct estimate of the mass and size of extrasolar planets orbiting around it.

So far the measure of "g" was obtained by evaluating the amplitude of the brightness variations. However many stars are too faint to be studied with this approach.
The new method is suggested to analyze the time-scale of these variations due to the surface convection (seen as granulations) and the acoustic oscillations (p-mode pulsation) reaching an error of just 4%.
One of the advantages of this new method (valid for stars with masses between 0.8 and 3 solar masses) is that it is largely independent of the activity level of a star.

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http://advances.sciencemag.org/content/2/1/e1500654.full

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Astrophysics News (March 22)

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