Long Term Variability Of The Coronal and Post - Coronal Regions Of The Oe Star HD 93521
Abstract
Introduction: As it is already known, the spectra of many Oe and Be stars present Discrete Absorption Components (DACs) which, due to their profiles' width as well as the values of the radial velocities, create a complicated profile of the main spectral lines (Bates & Halliwell, 1986). In this poster paper we detect the presence of this phenomenon (DACs or SACs) in the C IV, N IV and N V spectral lines of the star HD 93521 which is a relatively bright, very rapidly rotating O9.5V star (Conti & Ebbets, 1977; Hobbs et al., 1982; Lennon et al., 1991). Method: In our study we apply the method proposed by Danezis et al. (2003, 2005) on the spectra of the star HD 93521, taken with I.U.E. from 1979 until 1995 and we examine the timescale variations of the physical parameters, stated below. Results: As a first result we detect that the above spectral lines consist of one or more Satellite Absorption Components (SACs or DACs, Danezis et al., 2005). With the above method we calculate the time scale variation of the apparent rotational and radial velocities, the Gaussian standard deviation of the random motions of the ions, the random velocities of these motions, as well as the optical depth, the column density, the Full Width at Half Maximum (FWHM), the absorbed and the emitted energy of the independent regions of matter which produce the main and the satellites components of the studied spectral lines. Discussion: We point out that the new and important aspect of our study is the values' calculation of the above parameters and their time scale variations, using the DACs or SACs theory. Our results are a successful test of this theory and of Danezis et al. (2003, 2005) proposed method. This study is a part of a Ph. D. Thesis.
- Publication:
-
IAU Joint Discussion
- Pub Date:
- August 2006
- Bibcode:
- 2006IAUJD...4E...4A