Time-dependent spectral-feature variations of stars displaying the B[e] phenomenon III. HD 50138

Abstract

We analyse spectroscopic observations of the B[e] star HD 50138 (MWC 158, V743 Mon, or IRAS 06491-0654), a member of the FS CMa group, obtained over the last twenty years. Four different epochs are identified in the observational data, where the variability of the spectral features is substantially different. Additionally, two long periods of (3 000 +/- 500) and (5 000 +/- 1000) days are found in the variations of the equivalent widths of the H alpha and [OI] 6300 A lines and radial velocities of the H alpha line violet peak. Modest signatures of a regular period of ~34 days in the radial velocities of the H alpha red peak and H beta central depression are found in the season 2013/2014. The H alpha V/R changes indicate a periodicity of ~50 days. The correlations between individual spectral features significantly restricts the model of the object and suggest that it is most likely a binary system with a highly distorted disc with spiral arms around the primary component. At the same time, no obvious signs of the secondary component has been found in the object's spectrum.

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Cited by in corpus (9)

• Very massive stars in not so massive clusters
• A disk asymmetry in motion around the B[e] star MWC158
• First detection of a magnetic field in low-luminosity B[e] stars: New scenarios for the nature and evolutionary stages of FS CMa stars
• Dust evolution in the circumstellar disc of the unclassified B[e] star HD 50138
• 2.5-MHD models of circumstellar discs around FS~CMa post-mergers : I. Non-stationary accretion stage
• The mass distribution of stellar mergers: A new scenario for several FS CMa stars
• Intermediate-Mass Mergers: A New Scenario for Several FS CMa Stars
• 2.5-MHD models of circumstellar discs around FS~CMa post-mergers : II. Stationary accretion stage
• Velocity resolved [O I] 63 $\mu$m emission in the HD 50138 circumstellar disk