Astronomy and Astrophysics – Astronomy
Scientific paper
Dec 2007
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007aas...211.8102g&link_type=abstract
American Astronomical Society, AAS Meeting #211, #81.02; Bulletin of the American Astronomical Society, Vol. 39, p.871
Astronomy and Astrophysics
Astronomy
Scientific paper
The evolutionary paths of the massive O and B type stars are often defined by angular momentum transformations that involve circumstellar gas disks. This circumstellar gas is revealed in several kinds of observations, and I will describe a series of investigations of the hydrogen line emission from such disks using detailed studies of five massive binaries and a survey of 128 (mostly) Be stars.
By examining three sets of spectra of the active mass-transfer binary system RY Scuti, I determined masses of 7.1 ± 1.2 M_sun for the bright supergiant and 30.0 ± 2.1 M_sun for the massive companion that is hidden by an accretion torus. I will also present a cartoon model of the complex mass flows in the system.
Using optical spectroscopy and X-ray flux data, I investigated the mass transfer processes in four massive X-ray binaries (a massive B star with mass flowing onto a compact, neutron star companion). These systems are: LS I +61 303, LS I +65 010, HDE 245770, and X Persei. During the course of the analysis of these binaries, I developed numerical models for estimating the size of the Be star disks using just the H-alpha equivalent width.
Finally, I will present the results of a three year spectroscopic survey of both the H-alpha and H-gamma regions of 128 stars with hydrogen in emission (most are Be stars). I find that the median fractional variation in the equivalent width of the disk emission lines is 15% over a two year period. I also find that fully two-thirds of the sample displays evidence of Fe II emission or absorption resulting from surrounding circumstellar material. Many candidates for non-radial pulsation and binary systems are also found.
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