THE WISCONSIN HOT STAR GROUP

The Chandra X-ray image and spectrum of Zeta Orionis

• a description of hot star interests at the UW (below),
• a list of members of the Wisconsin Hot Star Group,
• recent preprints/reprints,
• and links to other pages on hot stars..

The Hot Star Group at UW Madison discusses and encourages collaborative research on problems concerning the atmospheres, winds and envelopes of stars with temperatures above about 10,000 K. Some classes of hot stars of special interest to us are:

• O stars. These are the hottest stars that can have their energy produced by the burning of hydrogen in their cores. The surface temperatures of O stars lie in the range 50,000 to 30,000K.
• B stars. These stars have temperatures in the range 30,000 to 10,000K
• Be stars are a special subclass of B stars, called emission line B stars for which the Halpha line at 6563 Angstroms is seen as an emission line. The Be stars are also rapid rotators, and the emission lines form in an extended envelope.
• Wolf-Rayet (or WR) stars are in a near terminal phase of stellar evolution. The stars have used up nearly all of their nuclear fuels. They show a photospheric spectrum with essentially no hydrogen, but strong emission lines from ionized helium. The spectra of WR stars are especially interesting because they show essentially nothing but emission lines. These lines form in the massive stellar winds from the stars. The cause of these stellar winds is still not well-understood.
• Novae Shells: The explosions associated with novae are produced by the nuclear burning at the base of a hydrogen rich layer that has been deposited on a white dwarf star by mass overflow from a companion star.
• Regions of Massive star formation. These include Ultracompact HII (UCHII) regions in which O stars spend the first 10% of their lives, and regions that show bipolar molecular outflows, which are thought to be produced during the collapse of a molecular cloud during star formation.

Questions about hot stars? Contact

Questions about Astronomy at the U. of Wisconsin? Contact

The UW homepage can be accessed from here.