A Low Metallicity Massive Contact Binary Star System Candidate in WLM Identified by Hubble and James Webb Space Telescope Imaging

Maude Gull; Daniel R. Weisz; Kareem El-Badry; Jan Henneco; Alessandro Savino; Meredith Durbin; Yumi Choi; Roger E. Cohen; Andrew A. Cole; Matteo Correnti; Julianne J. Dalcanton; Karoline M. Gilbert; Steven R. Goldman; Puragra Guhathakurta; Kristen B. W. McQuinn; Max J. B. Newman; Evan D. Skillman; Benjamin F. Williams

doi:10.3847/1538-4357/adca39

The Astrophysical Journal (Jan 2025)

A Low Metallicity Massive Contact Binary Star System Candidate in WLM Identified by Hubble and James Webb Space Telescope Imaging

Maude Gull,
Daniel R. Weisz,
Kareem El-Badry,
Jan Henneco,
Alessandro Savino,
Meredith Durbin,
Yumi Choi,
Roger E. Cohen,
Andrew A. Cole,
Matteo Correnti,
Julianne J. Dalcanton,
Karoline M. Gilbert,
Steven R. Goldman,
Puragra Guhathakurta,
Kristen B. W. McQuinn,
Max J. B. Newman,
Evan D. Skillman,
Benjamin F. Williams

Affiliations

Maude Gull: ORCiD; Department of Astronomy, University of California , Berkeley, Berkeley, CA 94720, USA
Daniel R. Weisz: ORCiD; Department of Astronomy, University of California , Berkeley, Berkeley, CA 94720, USA
Kareem El-Badry: ORCiD; Department of Astronomy, California Institute of Technology , Pasadena, CA 91125, USA
Jan Henneco: ORCiD; Heidelberger Institut für Theoretische Studien , Schloss-Wolfsbrunnenweg 35, 69118, Heidelberg, Germany; Universität Heidelberg , Im Neuenheimer Feld 226, 69120, Heidelberg, Germany
Alessandro Savino: ORCiD; Department of Astronomy, University of California , Berkeley, Berkeley, CA 94720, USA
Meredith Durbin: ORCiD; Department of Astronomy, University of California , Berkeley, Berkeley, CA 94720, USA
Yumi Choi: ORCiD; NSF National Optical-Infrared Astronomy Research Laboratory , 950 North Cherry Ave, Tucson, AZ 85719, USA
Roger E. Cohen: ORCiD; Department of Physics and Astronomy, Rutgers the State University of New Jersey , 136 Frelinghuysen Rd., Piscataway, NJ 08854, USA
Andrew A. Cole: ORCiD; Greenhill Observatory & School of Natural Sciences, University of Tasmania , Private Bag 37 Hobart, Tasmania 7001, Australia
Matteo Correnti: ORCiD; INAF Osservatorio Astronomico di Roma , Via Frascati 33, 00078, Monteporzio Catone, Rome, Italy; ASI-Space Science Data Center , Via del Politecnico, I-00133, Rome, Italy
Julianne J. Dalcanton: ORCiD; Center for Computational Astrophysics, Flatiron Institute , 162 Fifth Ave, New York, NY 10010, USA; Department of Astronomy, University of Washington , Box 351580, Seattle, WA 98195, USA
Karoline M. Gilbert: ORCiD; Space Telescope Science Institute , 3700 San Martin Dr., Baltimore, MD 21218, USA; The William H. Miller III Department of Physics & Astronomy, Bloomberg Center for Physics and Astronomy, Johns Hopkins University , 3400 N. Charles Street, Baltimore, MD 21218, USA
Steven R. Goldman: ORCiD; Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA
Puragra Guhathakurta: ORCiD; Department of Astronomy & Astrophysics, University of California Santa Cruz , 1156 High Street, Santa Cruz, CA 95064, USA
Kristen B. W. McQuinn: ORCiD; Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA; Department of Physics and Astronomy, Rutgers, The State University of New Jersey , 136 Frelinghuysen Rd., Piscataway, NJ 08854, USA
Max J. B. Newman: ORCiD; Department of Physics and Astronomy, Rutgers, The State University of New Jersey , 136 Frelinghuysen Rd., Piscataway, NJ 08854, USA
Evan D. Skillman: ORCiD; Minnesota Institute for Astrophysics, University of Minnesota , 116 Church Street South East, Minneapolis, MN 55455, USA
Benjamin F. Williams: ORCiD; Department of Astronomy, University of Washington , Box 351580, U.W., Seattle, WA 98195-1580, USA

DOI: https://doi.org/10.3847/1538-4357/adca39
Journal volume & issue: Vol. 986, no. 1
p. 25

Abstract

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We present archival Hubble Space Telescope (HST) and JWST ultraviolet through near-infrared time series photometric observations of a massive minimal-contact binary candidate in the metal-poor galaxy Wolf–Lundmark–Melotte ( Z = 0.14 Z _⊙ ). This discovery marks the lowest metallicity contact binary candidate observed to date. We determine the nature of the two stars in the binary by using the eclipsing binary modeling software PHysics Of Eclipsing BinariEs ( PHOEBE ) to train a neural network to fit our observed panchromatic multiepoch photometry. The best-fit model consists of two hot main-sequence stars ( ${T}_{1}=2980{0}_{-1700}^{+2300}$ K, ${M}_{1}=1{6}_{-3}^{+2}$ M _⊙ , and ${T}_{2}=1800{0}_{-5000}^{+5000}$ K, ${M}_{2}={7}_{-3}^{+5}$ M _⊙ ). We discuss plausible evolutionary paths for the system, and suggest the system is likely to be currently in a contact phase. Future spectroscopy will help to further narrow down evolutionary pathways. This work showcases a novel use of data of JWST and HST imaging originally taken to characterize RR Lyrae. We expect time series imaging from LSST, BlackGEM, etc. to uncover similar types of objects in nearby galaxies.

Published in The Astrophysical Journal

ISSN: 1538-4357 (Online)
Publisher: IOP Publishing
Country of publisher: United Kingdom
LCC subjects: Science: Astronomy: Astrophysics
Website: https://iopscience.iop.org/journal/0004-637X

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