THE H{alpha} VARIATIONS OF THE LUMINOUS BLUE VARIABLE P CYGNI: DISCRETE ABSORPTION COMPONENTS AND THE SHORT S DORADUS-PHASE
- Center for High Angular Resolution Astronomy, Department of Physics and Astronomy, Georgia State University, P.O. Box 4106, Atlanta, GA 30302-4106 (United States)
- Ritter Astrophysical Research Center, Department of Physics and Astronomy, University of Toledo, 2801 W. Bancroft, Toledo, OH 43606 (United States)
- Institute of Astronomy with National Astronomical Observatory, Bulgarian Academy of Sciences, P. O. Box 136, 4700 Smoljan (Bulgaria)
- Department of Physics, University of Notre Dame, 225 Nieuwland Science Hall, Notre Dame, IN 46556 (United States)
P Cygni is a prototype of the luminous blue variables (or S Doradus variables), and the star displays photometric and emission line variability on a timescale of years (known as the 'short S Doradus-phase' variations). Here we present new high-resolution H{alpha} spectroscopy of P Cyg that we combine with earlier spectra and concurrent V-band photometry to document the emission and continuum flux variations over a 24 year time span. We show that the emission and continuum fluxes vary in concert on timescales of 1.6 years and longer, but differ on shorter timescales. The H{alpha} profile shape also varies on the photometric timescales, and we describe the observed co-variations of the emission peak and absorption trough properties. We argue that the episodes of photometric and emission brightening are caused by increases in the size of the emission region that are related to variations in wind mass-loss rate and outflow speed. We find evidence of blueward accelerating, discrete absorption components (DACs) in the absorption trough of the H{alpha} profile, and these features have slower accelerations and longer durations than those observed in other lines. The DAC strengths also appear to vary on the photometric timescales, and we suggest that the propagation of the DAC-related wind structures is closely related to changes in the overall wind mass-loss rate and velocity.
- OSTI ID:
- 21583174
- Journal Information:
- Astronomical Journal (New York, N.Y. Online), Vol. 141, Issue 4; Other Information: DOI: 10.1088/0004-6256/141/4/120; ISSN 1538-3881
- Country of Publication:
- United States
- Language:
- English
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