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Photometric and H-Alpha Variability in Some Be Stars

Published online by Cambridge University Press:  23 September 2016

S. Catalano  and
G. Umana
S. Catalano
Affiliation:
Istituto di Astronomia, Universita di Catania, Viale A. Doria, 95125 Catania, C.N.R., Gruppo Nazionale di Astronomia UdR Catania, Italy
G. Umana
Affiliation:
Istituto di Astronomia, Universita di Catania, Viale A. Doria, 95125 Catania, C.N.R., Gruppo Nazionale di Astronomia UdR Catania, Italy

Extract

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Short-term variations, typically with small amplitude (Δm < 0.1 mag.), time-scales of hours or near one day and in many cases correlated with the rotation period have been found to be commonplace among Be stars (see Harmanec and Pavlovski 1983 for review and papers). Radial and non-radial pulsation modes have been proposed to explain this variability. However, the light curves are often double-peaked, at first suggesting the stars may have large organized dipole magnetic fields and spots not unlike those in the Ap or Bp stars (Harmanec 1983). These rotationally modulated variations are not stable, and seem to vary in both amplitude and period in the sense that intervals with well defined light curves alternate with intervals when variations are absent. This phenomenon is very reminiscent of formation and apparent relative movement in longitude of spots (groups) in some RS CVn binaries (Catalano 1983, Rodono 1986), but on a much more rapid time scale.

Type
IIA. The Underlying Stars: Observations
Information
International Astronomical Union Colloquium , Volume 92: Physics of Be Stars , August 1987 , pp. 101 - 103
Copyright
Copyright © Cambridge University Press 1987

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