Article

A noninteracting low-mass black hole–giant star binary system

Todd A. ThompsonCenter for Cosmology and AstroParticle Physics, The Ohio State University, 191 W. Woodruff Ave., Columbus, OH 43210, USAC. S. KochanekCenter for Cosmology and AstroParticle Physics, The Ohio State University, 191 W. Woodruff Ave., Columbus, OH 43210, USAKrzysztof Z. StanekCenter for Cosmology and AstroParticle Physics, The Ohio State University, 191 W. Woodruff Ave., Columbus, OH 43210, USACarles BadenesDepartment of Physics and Astronomy and Pittsburgh Particle Physics, Astrophysics and Cosmology Center, University of Pittsburgh, 3941 O’Hara St., Pittsburgh, PA 15260, USAR. S. PostPost Observatory, Lexington, MA 02421, USAT. JayasingheCenter for Cosmology and AstroParticle Physics, The Ohio State University, 191 W. Woodruff Ave., Columbus, OH 43210, USADavid W. LathamHarvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138, USAAllyson BierylaHarvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138, USAGilbert A. EsquerdoHarvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138, USAP. BerlindHarvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138, USAM. CalkinsHarvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138, USAJamie TayarDepartment of Astronomy, The Ohio State University, 140 W. 18th Ave., Columbus, OH 43210, USAL. LindegrenLund Observatory, Department of Astronomy and Theoretical Physics, Lund University, Box 43, 22100 Lund, SwedenJennifer A. JohnsonCenter for Cosmology and AstroParticle Physics, The Ohio State University, 191 W. Woodruff Ave., Columbus, OH 43210, USAT. W. S. HoloienThe Observatories of the Carnegie Institution for Science, 813 Santa Barbara St., Pasadena, CA 91101, USAKatie AuchettlCenter for Cosmology and AstroParticle Physics, The Ohio State University, 191 W. Woodruff Ave., Columbus, OH 43210, USAKevin R. CoveyDepartment of Physics and Astronomy, Western Washington University, Mail Stop 9164, Bellingham, WA, 98225, USA

2019en

ABI

Abstract

Black hole binary systems with companion stars are typically found via their x-ray emission, generated by interaction and accretion. Noninteracting binaries are expected to be plentiful in the Galaxy but must be observed using other methods. We combine radial velocity and photometric variability data to show that the bright, rapidly rotating giant star 2MASS J05215658+4359220 is in a binary system with a massive unseen companion. The system has an orbital period of ~83 days and near-zero eccentricity. The photometric variability period of the giant is consistent with the orbital period, indicating star spots and tidal synchronization. Constraints on the giant's mass and radius imply that the unseen companion is [Formula: see text] solar masses, indicating that it is a noninteracting low-mass black hole or an unexpectedly massive neutron star.

Identifiers

DOI: 10.1126/science.aau4005

Citations and references

Cited by 30 references

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