Spectroscopic evidence for a large spot on the dimming Betelgeuse

Abstract

During October 2019 and March 2020, the luminous red supergiant Betelgeuse demonstrated an unusually deep minimum of its brightness. It became fainter by more than one magnitude and this is the most significant dimming observed in the recent decades. While the reason for the dimming is debated, pre-phase of supernova explosion, obscuring dust, or changes in the photosphere of the star were suggested scenarios. Here, we present spectroscopic studies of Betelgeuse using high-resolution and high signal-to- noise ratio near-infrared spectra obtained at Weihai Observatory on four epochs in 2020 covering the phases of during and after dimming. We show that the dimming episode is caused by the dropping of its effective temperature by at least 170 K on 2020 January 31, that can be attributed to the emergence of a large dark spot on the surface of the star.

References in corpus (20)

• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• The Effective Temperature Scale of Galactic Red Supergiants: Cool, But Not As Cool As We Thought
• Fundamental parameters and infrared excesses of Hipparcos stars
• The Effective Temperatures and Physical Properties of Magellanic Cloud Red Supergiants: The Effects of Metallicity
• The atmospheric parameters and spectral interpolator for the stars of MILES
• Imaging the spotty surface of Betelgeuse in the H band
• The close circumstellar environment of Betelgeuse - V. Rotation velocity and molecular envelope properties from ALMA
• Betelgeuse Just Isn't That Cool: Effective Temperature Alone Cannot Explain the Recent Dimming of Betelgeuse
• The Photospheric Temperatures of Betelgeuse during the Great Dimming of 2019/2020: No New Dust Required
• The photometric system of the One-meter Telescope at Weihai Observatory of Shandong University
• The atmospheric structure and fundamental parameters of the red supergiants AH Sco, UY Sct and KW Sgr
• Accuracy of atmospheric parameters of FGK dwarfs determined by spectrum fitting
• Spatially Resolved Ultraviolet Spectroscopy of the Great Dimming of Betelgeuse
• NLTE line formation for Mg\ione\ and Mg\ii\ in atmospheres of B-A-F-G-K stars
• Non-LTE Sodium Abundance in Galactic Thick- and Thin-Disk Red Giants
• Betelgeuse fainter in the sub-millimetre too: an analysis of JCMT and APEX monitoring during the recent optical minimum
• Early Warning Signals Indicate a Critical Transition in Betelgeuse
• SOFIA-EXES Observations of Betelgeuse during the Great Dimming of 2019/2020
• The convective photosphere of the red supergiant CE Tau. I. VLTI/PIONIER H-band interferometric imaging
• WES - Weihai Echelle Spectrograph

Cited by in corpus (4)

• The Great Dimming of Betelgeuse: a Surface Mass Ejection (SME) and its Consequences
• The Great Dimming of Betelgeuse seen by the Himawari-8 meteorological satellite
• Betelgeuse, the Prototypical Red Supergiant
• Evidence for dynamical changes in Betelgeuse using multi-wavelength data