Spectra of Be Stars
12.5" Newtonian and Star Analyzer
Uploaded 10/27/12

An interesting subclass of the B type stars is known as the Be Stars. The spectrum of these stars has at one time or another an emission component, usually in the hydrogen lines. The star Gamma Cassiopeia was the first of these emission stars discovered using visual spectroscopes over a century ago in 1866, and is considered an excellent starting point for exploring this type of object.

Today, most astronomers agree that this is rapidly rotating giant star, which has thrown off its outer hydrogen atmosphere, orbiting at a close range. The UV from the B star then ionizes this hydrogen and causes its excitation, and dust in the gaseous envelope also reveals polarization in its dust particles.

Be stars are also variable in light output, some with smaller companion stars that loop through the gas torus cause periodic outbursts in the emission lines. Even the Hubble space telescope cannot clearly see these tiny dust and gas envelopes around Be stars. The fact that we can record their presence and measure their velocities with amateur instruments is quite extraordinary!

I will be starting with a few of the brighter and more easily spectrally resolved stars, then adding fainter or more exotic examples later. All spectra here are normalized to the calibrated continuum data.
Click to enlarge to full 1024 size:
Gamma Cass B0 IVevar
Alberio B B8 Ve
  Beta Lyra B8 II

Instrument: 12.5" f/5 Home made Newtonian Grating: Star Analyzer 100 lpmm Mount: Astrophysics 1200 QMD CCD Camera: DMK51 Imaging Source Location: Payson, Arizona, Elevation: 5150 ft. Sky: Seeing FWHM = 5 arcsec , Transparency 9/10 Outside Temperature: 55 F Image Processing Tools: RSpec for spectral extraction, Photoshop CS2 HOME GALAXIES EMISSION NEBS REFLECTION NEBS COMETS GLOBULARS OPEN CLUST PLANETARIES LINKS