What are Be stars?
Discovered in 1867 by Secchi
B stars = hot (blue) ; T = 20000 K = 3-4 Tsun
non-supergiant
M = 8 Msun
R = 6 Rsun
variables
and... have at least one emission line.
Be = B emission
20% of B stars are Be
Be stars have to be studied to understand the phenomen:
To observe the disk of matter (Halpha)
To know the long term variations (via the pulsations)
To know if there are variations linked to the magnetic dipole rotation (Zeeman effect)
Be star spectrum - continuum + emission/absorbtion line + rotational effect
Amateur spectroscopy of Be stars: see this site:
http://www.astrosurf.com/buil/us/bestar.htm
