The optical spectra of B-type stars predominantly contain absorption lines of hydrogen and
neutral helium (HeI), which means that the they have an effective temperature range of
between 10000K and 30000K. Main sequence luminosities are between 130 and 64000 L
,
with respective masses and radii of between 3.4-17.5 M & 2.8-7.7 R (Schmidt-Kaler, 1982).
Other spectral features may include lines from CaII, CII, CIII, NII, NIII, OII, SiII, SiIV, and
MgII species.
Stars which have temperatures high enough to ionise helium (HeII) are called “O” stars and are the hottest stars at ~50000K, while stars which are not hot enough to exhibit HeI lines have spectra which are dominated by hydrogen (HI) and are called “A” stars, usually present are a few heavier elements along with CaII, H and K, temperatures are <10000K.
B-type dwarfs, giants and supergiants together with O-type stars form the main constituents of OB associations. It is these groups of stars that delineate the spiral arms of galaxies where the majority of current star formation occurs.
Print
Email
News!