Morgan MacLeod, Sarah Blunt, Robert J. De Rosa, Andrea K. Dupree, Thomas Granzer, Graham M. Harper, Caroline D. Huang, Emily M. Leiner, Abraham Loeb, Eric L. Nielsen, Klaus G. Strassmeier, Jason J. Wang, Michael Weber
{"title":"Radial Velocity and Astrometric Evidence for a Close Companion to Betelgeuse","authors":"Morgan MacLeod, Sarah Blunt, Robert J. De Rosa, Andrea K. Dupree, Thomas Granzer, Graham M. Harper, Caroline D. Huang, Emily M. Leiner, Abraham Loeb, Eric L. Nielsen, Klaus G. Strassmeier, Jason J. Wang, Michael Weber","doi":"arxiv-2409.11332","DOIUrl":null,"url":null,"abstract":"We examine a century of radial velocity, visual magnitude, and astrometric\nobservations of the nearest red supergiant, Betelgeuse, in order to reexamine\nthe century-old assertion that Betelgeuse might be a spectroscopic binary.\nThese data reveal Betelgeuse varying stochastically over years and decades due\nto its boiling, convective envelope, periodically with a $ 5.78$~yr long\nsecondary period, and quasi-periodically from pulsations with periods of\nseveral hundred days. We show that the long secondary period is consistent\nbetween astrometric and RV datasets, and argue that it indicates a low-mass\ncompanion to Betelgeuse, less than a solar mass, orbiting in a 2,110 day period\nat a separation of just over twice Betelgeuse's radius. The companion star\nwould be nearly twenty times less massive and a million times fainter than\nBetelgeuse, with similar effective temperature, effectively hiding it in plain\nsight near one of the best-studied stars in the night sky. The astrometric data\nfavor an edge-on binary with orbital plane aligned with Betelgeuse's measured\nspin axis. Tidal spin-orbit interaction drains angular momentum from the orbit\nand spins up Betelgeuse, explaining the spin--orbit alignment and Betelgeuse's\nanomalously rapid spin. In the future, the orbit will decay until the companion\nis swallowed by Betelgeuse in the next 10,000 years.","PeriodicalId":501068,"journal":{"name":"arXiv - PHYS - Solar and Stellar Astrophysics","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"arXiv - PHYS - Solar and Stellar Astrophysics","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/arxiv-2409.11332","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
We examine a century of radial velocity, visual magnitude, and astrometric
observations of the nearest red supergiant, Betelgeuse, in order to reexamine
the century-old assertion that Betelgeuse might be a spectroscopic binary.
These data reveal Betelgeuse varying stochastically over years and decades due
to its boiling, convective envelope, periodically with a $ 5.78$~yr long
secondary period, and quasi-periodically from pulsations with periods of
several hundred days. We show that the long secondary period is consistent
between astrometric and RV datasets, and argue that it indicates a low-mass
companion to Betelgeuse, less than a solar mass, orbiting in a 2,110 day period
at a separation of just over twice Betelgeuse's radius. The companion star
would be nearly twenty times less massive and a million times fainter than
Betelgeuse, with similar effective temperature, effectively hiding it in plain
sight near one of the best-studied stars in the night sky. The astrometric data
favor an edge-on binary with orbital plane aligned with Betelgeuse's measured
spin axis. Tidal spin-orbit interaction drains angular momentum from the orbit
and spins up Betelgeuse, explaining the spin--orbit alignment and Betelgeuse's
anomalously rapid spin. In the future, the orbit will decay until the companion
is swallowed by Betelgeuse in the next 10,000 years.