Skip to main content

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.

► Read more>>
http://advances.sciencemag.org/content/2/1/e1500654.full

► Image Credit:
Wikimedia Common

Comments

Popular posts from this blog

ORBITAL PERIODS OF THE PLANETS

For orbital period generally we refer to the sidereal period, that is the temporal cycle that it takes an object to make a full orbit, relative to the stars. This is the orbital period in an inertial (non-rotating) frame of reference (365,25 days for the earth).

THE HITCHCHIKER'S GUIDE TO THE LOCAL SUPERCLUSTER

Image: Virgo Supercluster. Credit: Andrew Z. Colvin The Virgo Supercluster is a region with a diameter of 33 megaparsecs (~1000 times larger the Milky Way's diameter) containing at least 100 galaxy groups and clusters.

MILLISECOND PULSAR ORIGIN OF THE GALACTIC CENTER GEV EXCESS

Image: The Milky Way. Credit: Serge Brunier Using γ-ray data from the Fermi Large Area Telescope, various groups have identified a clear excess emission in the inner Galaxy, at energies around a few GeV. This excess attracted great attention, because it has properties typical for a dark matter annihilation signal.