Betelgeuse Fainter in the Submillimeter Too: An Analysis of JCMT and APEX Monitoring during the Recent Optical Minimum
Thavisha E. Dharmawardena, Steve Mairs, Peter Scicluna, Graham Bell, Iain McDonald, Karl Menten, Axel Weiss, Albert Zijlstra
Abstract
Abstract Betelgeuse, the nearest red supergiant star to Earth, underwent an unusually deep minimum at optical wavelengths during its most recent pulsation cycle. We present submillimeter observations taken by the James Clerk Maxwell Telescope and Atacama Pathfinder Experiment over a time span of 13 yr including the optical dimming. We find that Betelgeuse has also dimmed by ∼20% at these longer wavelengths during this optical minimum. Using radiative-transfer models, we show that this is likely due to changes in the photosphere (luminosity) of the star as opposed to the surrounding dust, as was previously suggested in the literature.