The Betelgeuse Project: Constraints from Rotation

Abstract

In order to constrain the evolutionary state of the red supergiant Betelgeuse, we have produced a suite of models with ZAMS masses from 15 to 25 Msun in intervals of 1 Msun including the effects of rotation. The models were computed with the stellar evolutionary code MESA. For non-rotating models we find results that are similar to other work. It is somewhat difficult to find models that agree within 1 sigma of the observed values of R, Teff and L, but modestly easy within 3 sigma uncertainty. Incorporating the nominal observed rotational velocity, ~15 km/s, yields significantly different, and challenging, constraints. This velocity constraint is only matched when the models first approach the base of the red supergiant branch (RSB), having crossed the Hertzsprung gap, but not yet having ascended the RSB and most violate even generous error bars on R, Teff and L. Models at the tip of the RSB typically rotate at only ~0.1 km/s, independent of any reasonable choice of initial rotation. We discuss the possible uncertainties in our modeling and the observations, including the distance to Betelgeuse, the rotation velocity, and model parameters. We summarize various options to account for the rotational velocity and suggest that one possibility is that Betelgeuse merged with a companion star of about 1 Msun as it ascended the RSB, in the process producing the ring structure observed at about 7' away. A past coalescence would complicate attempts to understand the evolutionary history and future of Betelgeuse.

arXiv comment7 pages, 7 figures

References in corpus (18)

• Modules for Experiments in Stellar Astrophysics (MESA)
• Modules for Experiments in Stellar Astrophysics (MESA): Giant Planets, Oscillations, Rotation, and Massive Stars
• Modules for Experiments in Stellar Astrophysics (MESA): Binaries, Pulsations, and Explosions
• Binary interaction dominates the evolution of massive stars
• Hubble Space Telescope Fine Guidance Sensor Parallaxes of Galactic Cepheid Variable Stars: Period-Luminosity Relations
• The incidence of stellar mergers and mass gainers among massive stars
• The VLT-FLAMES Tarantula Survey XXII. Multiplicity properties of the B-type stars
• The VLT-FLAMES Tarantula Survey X: Evidence for a bimodal distribution of rotational velocities for the single early B-type stars
• The enigmatic nature of the circumstellar envelope and bow shock surrounding Betelgeuse as revealed by Herschel. I. Evidence of clumps, multiple arcs, and a linear bar-like structure
• The close circumstellar environment of Betelgeuse - Adaptive optics spectro-imaging in the near-IR with VLT/NACO
• Interacting supernovae from photoionization-confined shells around red supergiant stars
• 3D Simulations of Betelgeuse's Bow Shock
• Evolutionary tracks for Betelgeuse
• N2H+ and HC3N Observations of the Orion A Cloud
• The Role of the Magnetorotational Instability in Massive Stars
• Discovery of a detached HI gas shell surrounding alpha Orionis
• Kepler rapidly rotating giant stars
• The past and future evolution of a star like Betelgeuse

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• Spatially Resolved Ultraviolet Spectroscopy of the Great Dimming of Betelgeuse
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• The Great Dimming of Betelgeuse seen by the Himawari-8 meteorological satellite
• Is Betelgeuse Really Rotating? Synthetic ALMA Observations of Large-scale Convection in 3D Simulations of Red Supergiants
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• The Betelgeuse Project II: Asteroseismology
• Stellar models of Betelgeuse constrained using observed surface conditions
• History of two mass loss processes in VY CMa. Fast outflows carving older ejecta
• The Betelgeuse Project III: Merger Characteristics
• MAGIS (Measuring Abundances of red super Giants with Infrared Spectroscopy) project I. Establishment of an abundance analysis procedure for red supergiants and its evaluation with nearby stars
• Betelgeuse, the Prototypical Red Supergiant
• Asteroseismology: Looking for axions in the red supergiant star Alpha Ori