TESS observations of Be stars: a new interpretation

Abstract

Light curves of 57 classical Be stars in TESS sectors 1 - 15 are examined. In most Be stars, the periodogram shows groups at a fundamental and one or more harmonics, which we attribute to rotation. In about 40 percent of the stars, the group is just a single narrow or slightly broadened peak. In about 30 percent, it consists of a multiple, closely spaced peaks. These groups can be interpreted as non-coherent variations most likely associated with photospheric gas clouds. Approximate rotational frequencies for about 75 percent of the stars can be derived. Comparison with the projected rotational velocities shows that the photometric frequency is consistent with rotation. The first harmonic plays a prominent role in many Be stars and manifests itself in either single-wave or double-wave light curves. The reduction in amplitude of beta Cep pulsations in a few Be stars during an outburst and their subsequent recovery is most likely an obscuration effect. Other instances of possible obscuration of the photosphere are suspected. A simple model, which attempts to explain these observations and other general properties of Be stars, is proposed.

17 pages 17 figures 3 Tables

References in corpus (26)

• The Gaia mission
• Dynamical Simulations of Magnetically Channeled Line-Driven Stellar Winds: II. The Effects of Field-Aligned Rotation
• Dynamical Simulations of Magnetically Channeled Line-Driven Stellar Winds: III. Angular Momentum Loss and Rotational Spindown
• The MiMeS survey of magnetism in massive stars: Magnetic analysis of the O-type stars
• Comparative statistics and origin of triple and quadruple stars
• Spectroscopic analysis of southern B and Be stars
• Variability Properties of 4 Million Sources in the $TESS$ Input Catalog Observed with the Kilodegree Extremely Little Telescope Survey
• A Multi-Membership Catalogue for 1876 Open Clusters using UCAC4 data
• BRITE-Constellation high-precision time-dependent photometry of the early-O-type supergiant $\zeta$ Puppis unveils the photospheric drivers of its small- and large-scale wind structures
• MONOS: Multiplicity Of Northern O-type Spectroscopic systems. I. Project description and spectral classifications and visual multiplicity of previously known objects
• MOBSTER - II. Identification of rotationally variable A stars observed with \emph{TESS} in Sectors 1 to 4
• MOST Detects g-Modes in the Late-Type be Star beta CMi (B8Ve)
• Rotational modulation in TESS B stars
• The Hot Companion and Circumbinary Disk of the Be Star HR 2142
• MOST detects corotating bright spots on the mid-O type giant ξ Persei
• Accurate age determinations of several nearby open clusters containing magnetic Ap stars
• MOST detects SPBe pulsations in HD 127756 & HD 217543: Asteroseismic rotation rates independent of vsini
• 3D Stellar Reddening Map from 2MASS Photometry: An Improved Version
• Short-term variability and mass loss in Be stars II. Physical taxonomy of photometric variability observed by the Kepler spacecraft
• Stellar parameters and H$\alpha$ line profile variability of Be stars in the BeSOS survey
• The close-in companion of the fast rotating Be star Achernar
• Exocomet signatures around the A-shell star $\Phi$ Leo?
• Evidence for spots on hot stars suggests major revision of stellar physics
• Stellar parameters of Be stars observed with X-shooter
• Properties and nature of Be stars XXIII. Long-term variations and physical properties of kappa Dra
• A new look into putative duplicity and pulsations of the Be star $\beta$ CMi

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• $\nu$ Gem: a hierarchical triple system with an outer Be star
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• Short-term variability and mass loss in Be stars VI. Frequency groups in $\gamma$ Cas detected by TESS
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• Populations of evolved massive binary stars in the Small Magellanic Cloud II: Predictions from rapid binary evolution
• A study of the F-giant star $\theta$ Scorpii A: a post-merger rapid rotator?
• The TESS Mission Target Selection Procedure
• Fast time optical variability in Be/X-ray binaries. Pulsation and rotation
• Periodicity search for Pulsar Binaries with TESS
• Automated photometry of $\gamma$ Cassiopeiae:the last roundup
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