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Session 48 - Circumstellar Envelopes.
Display session, Tuesday, January 14
Metropolitan Ballroom,

[48.06] Rates of Energy Gain and Loss in the Circumstellar Envelopes of Be Stars: the PM Model

C. E. Millar, J. M. Marlborough (U.W.O.)

The validity of the assumed kinetic temperature of the gas in circumstellar envelopes of early Be stars was investigated using the model developed by Poeckert and Marlborough (1978). We determined the rate of energy gain and the rate of energy loss at numerous positions spaced throughout the envelope. For a particular temperature choice, we calculated the atomic level populations in order to determine these energy rates. A unit volume of gas gains energy from photoionization, collisional de-excitation of bound levels and free-free absorption; it loses energy by recombination, collisional excitation and free-free emission. If the assumed temperature were correct the rate of energy gain would equal the rate of energy loss exactly. Our results demonstrate that the kinetic temperature of 20,000 K, assumed by Poeckert and Marlborough, was a reasonable choice. However, a temperature of 15,000 K yields a better balance of the rates of energy gain and loss.

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