Betelgeuse: Detection of the Expanding Wake of the Companion Star

TL;DR

This paper presents evidence of a companion star orbiting Betelgeuse, with spectral signatures indicating a trailing wake and circumstellar variations aligned with a 2000-day orbital period.

Contribution

It provides the first detection and analysis of Betelgeuse's companion and its expanding wake through spectroscopic and speckle imaging data.

Findings

Spectroscopic signatures of variable circumstellar absorption.

Ultraviolet and optical lines show outflows linked to the companion.

Absorption and outflow variations correlate with the companion’s orbit.

Abstract

Recent analyses conclude that Betelgeuse, a red supergiant star (HD 39801), likely has a companion object with a period of about 2000 days orbiting at only 2.3 stellar radii, deep in the chromosphere of the supergiant. A probable detection of such a companion, named Siwarha, has just occurred from speckle imaging. This study finds that Betelgeuse spectra in the optical region and ultraviolet exhibit signatures of variable circumstellar absorption and chromospheric outflows. These variations are consistent with the ~ 2000-day period of the companion object. Circumstellar absorption evident in optical Mn I lines, and mass outflow marked by ultraviolet Fe II, Si I, and Mg I lines increase after the transit of the companion across the disk of Betelgeuse. Following the eclipse of the companion, the absorption and outflow slowly decrease in advance of the next transit. The occurrence and variation of this plasma appear consistent with the presence of a trailing and expanding wake caused by a companion star orbiting within the atmosphere of Betelgeuse.