Astrophysics (index)about

stellar radius determination

(methods by which the radius of a star is determined)

Stellar radius determination is generally approximated by the formula relating luminosity, temperature, and radius:

L = 4πR²sT4

Or if the values are known in terms of the Sun's values:

R/RSun=(TSun/T)²(L/LSun)1/2

Both L and T need to be measured or estimated. Temperature is generally related to the B-V color index. With a parallax distance measurement, L is related to the apparent magnitude. This yields a very rough estimate: merely basing the temperature on b-v can result in a radius off by as much as 50%.

When a parallax distance is not available, an even rougher estimate can be made using the mass-luminosity relation and mass-radius relation.

More accurate determination uses:

Only a few hundred stars have been measured by these more accurate methods. Using the more accurate radius in the above formula can sometimes yield a more accurate temperature determination.

One use for the radius is in the study of transiting extra-solar planets, to determine characteristics of the planet's orbit.


(stars,astrophysics,radius)
http://en.wikipedia.org/wiki/Luminosity
http://skyserver.sdss.org/dr1/en/proj/advanced/hr/radius1.asp
http://star-www.st-and.ac.uk/~kdh1/sea/sea09.pdf

Referenced by:
asteroseismology
California-Kepler Survey (CKS)
Palomar Testbed Interferometer (PTI)
stellar luminosity determination
stellar parameter determination

index