The First Ultracompact Roche Lobe-Filling Hot Subdwarf Binary

Thomas Kupfer; Evan B. Bauer; Thomas R. Marsh; Jan Van Roestel; Eric C. Bellm; Kevin B. Burdge; Michael W. Coughlin; Jim Fuller; J. J. Hermes; Lars Bildsten; Shrinivas R. Kulkarni; Thomas A. Prince; Paula Szkody; Vik S. Dhillon; Gabriel Murawski; Rick Burruss; Richard Dekany; Alex Delacroix; Andrew J. Drake; Dmitry A. Duev; Michael Feeney; Matthew J. Graham; David L. Kaplan; Russ R. Laher; S. P. Littlefair; Frank J. Masci; Reed Riddle; Ben Rusholme; Eugene Serabyn; Roger M. Smith; David L. Shupe; Maayane T. Soumagnac

doi:10.3847/1538-4357/ab72ff

The First Ultracompact Roche Lobe-Filling Hot Subdwarf Binary

Thomas Kupfer, Evan B. Bauer, Thomas R. Marsh, Jan Van Roestel, Eric C. Bellm, Kevin B. Burdge, Michael W. Coughlin, Jim Fuller, J. J. Hermes, Lars Bildsten, Shrinivas R. Kulkarni, Thomas A. Prince, Paula Szkody, Vik S. Dhillon, Gabriel Murawski, Rick Burruss, Richard Dekany, Alex Delacroix, Andrew J. Drake, Dmitry A. DuevMichael Feeney, Matthew J. Graham, David L. Kaplan, Russ R. Laher, S. P. Littlefair, Frank J. Masci, Reed Riddle, Ben Rusholme, Eugene Serabyn, Roger M. Smith, David L. Shupe, Maayane T. Soumagnac

Department of Particle Physics and Astrophysics

Weizmann Institute of Science

Research output: Contribution to journal › Article › peer-review

Abstract

We report the discovery of the first short-period binary in which a hot subdwarf star (sdOB) filled its Roche lobe and started mass transfer to its companion. The object was discovered as part of a dedicated high-cadence survey of the Galactic plane named the Zwicky Transient Facility and exhibits a period of P = 39.3401(1) minutes, making it the most compact hot subdwarf binary currently known. Spectroscopic observations are consistent with an intermediate He-sdOB star with an effective temperature of T_eff = 42,400 ± 300 K and a surface gravity of log_g = 5.77 ± 0.05. A high signal-to-noise ratio GTC+HiPERCAM light curve is dominated by the ellipsoidal deformation of the sdOB star and an eclipse of the sdOB by an accretion disk. We infer a low-mass hot subdwarf donor with a mass M _sdOB = 0.337 ± 0.015 M_⊙ and a white dwarf accretor with a mass M _WD = 0.545 ± 0.020 M_⊙. Theoretical binary modeling indicates the hot subdwarf formed during a common envelope phase when a 2.5-2.8 M_⊙ star lost its envelope when crossing the Hertzsprung gap. To match its current P_orb, T_eff, log_g, and masses, we estimate a post-common envelope period of P_orb ≈ 150 minutes and find that the sdOB star is currently undergoing hydrogen shell burning. We estimate that the hot subdwarf will become a white dwarf with a thick helium layer of ≈0.1 M_⊙, merge with its carbon/oxygen white dwarf companion after ≈17 Myr, and presumably explode as a thermonuclear supernova or form an R CrB star.

Original language	English
Article number	45
Number of pages	15
Journal	Astrophysical Journal
Volume	891
Issue number	1
DOIs	https://doi.org/10.3847/1538-4357/ab72ff
State	Published - 1 Mar 2020

All Science Journal Classification (ASJC) codes

Astronomy and Astrophysics
Space and Planetary Science

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Kupfer, T., Bauer, E. B., Marsh, T. R., Roestel, J. V., Bellm, E. C., Burdge, K. B., Coughlin, M. W., Fuller, J., Hermes, J. J., Bildsten, L., Kulkarni, S. R., Prince, T. A., Szkody, P., Dhillon, V. S., Murawski, G., Burruss, R., Dekany, R., Delacroix, A., Drake, A. J., ... Soumagnac, M. T. (2020). The First Ultracompact Roche Lobe-Filling Hot Subdwarf Binary. Astrophysical Journal, 891(1), Article 45. https://doi.org/10.3847/1538-4357/ab72ff

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title = "The First Ultracompact Roche Lobe-Filling Hot Subdwarf Binary",

abstract = "We report the discovery of the first short-period binary in which a hot subdwarf star (sdOB) filled its Roche lobe and started mass transfer to its companion. The object was discovered as part of a dedicated high-cadence survey of the Galactic plane named the Zwicky Transient Facility and exhibits a period of P = 39.3401(1) minutes, making it the most compact hot subdwarf binary currently known. Spectroscopic observations are consistent with an intermediate He-sdOB star with an effective temperature of Teff = 42,400 ± 300 K and a surface gravity of logg = 5.77 ± 0.05. A high signal-to-noise ratio GTC+HiPERCAM light curve is dominated by the ellipsoidal deformation of the sdOB star and an eclipse of the sdOB by an accretion disk. We infer a low-mass hot subdwarf donor with a mass M sdOB = 0.337 ± 0.015 M⊙ and a white dwarf accretor with a mass M WD = 0.545 ± 0.020 M⊙. Theoretical binary modeling indicates the hot subdwarf formed during a common envelope phase when a 2.5-2.8 M⊙ star lost its envelope when crossing the Hertzsprung gap. To match its current Porb, Teff, logg, and masses, we estimate a post-common envelope period of Porb ≈ 150 minutes and find that the sdOB star is currently undergoing hydrogen shell burning. We estimate that the hot subdwarf will become a white dwarf with a thick helium layer of ≈0.1 M⊙, merge with its carbon/oxygen white dwarf companion after ≈17 Myr, and presumably explode as a thermonuclear supernova or form an R CrB star.",

author = "Thomas Kupfer and Bauer, {Evan B.} and Marsh, {Thomas R.} and Roestel, {Jan Van} and Bellm, {Eric C.} and Burdge, {Kevin B.} and Coughlin, {Michael W.} and Jim Fuller and Hermes, {J. J.} and Lars Bildsten and Kulkarni, {Shrinivas R.} and Prince, {Thomas A.} and Paula Szkody and Dhillon, {Vik S.} and Gabriel Murawski and Rick Burruss and Richard Dekany and Alex Delacroix and Drake, {Andrew J.} and Duev, {Dmitry A.} and Michael Feeney and Graham, {Matthew J.} and Kaplan, {David L.} and Laher, {Russ R.} and Littlefair, {S. P.} and Masci, {Frank J.} and Reed Riddle and Ben Rusholme and Eugene Serabyn and Smith, {Roger M.} and Shupe, {David L.} and Soumagnac, {Maayane T.}",

year = "2020",

month = mar,

day = "1",

doi = "10.3847/1538-4357/ab72ff",

language = "الإنجليزيّة",

volume = "891",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "IOP Publishing Ltd.",

number = "1",

}

Kupfer, T, Bauer, EB, Marsh, TR, Roestel, JV, Bellm, EC, Burdge, KB, Coughlin, MW, Fuller, J, Hermes, JJ, Bildsten, L, Kulkarni, SR, Prince, TA, Szkody, P, Dhillon, VS, Murawski, G, Burruss, R, Dekany, R, Delacroix, A, Drake, AJ, Duev, DA, Feeney, M, Graham, MJ, Kaplan, DL, Laher, RR, Littlefair, SP, Masci, FJ, Riddle, R, Rusholme, B, Serabyn, E, Smith, RM, Shupe, DL & Soumagnac, MT 2020, 'The First Ultracompact Roche Lobe-Filling Hot Subdwarf Binary', Astrophysical Journal, vol. 891, no. 1, 45. https://doi.org/10.3847/1538-4357/ab72ff

TY - JOUR

T1 - The First Ultracompact Roche Lobe-Filling Hot Subdwarf Binary

AU - Kupfer, Thomas

AU - Bauer, Evan B.

AU - Marsh, Thomas R.

AU - Roestel, Jan Van

AU - Bellm, Eric C.

AU - Burdge, Kevin B.

AU - Coughlin, Michael W.

AU - Fuller, Jim

AU - Hermes, J. J.

AU - Bildsten, Lars

AU - Kulkarni, Shrinivas R.

AU - Prince, Thomas A.

AU - Szkody, Paula

AU - Dhillon, Vik S.

AU - Murawski, Gabriel

AU - Burruss, Rick

AU - Dekany, Richard

AU - Delacroix, Alex

AU - Drake, Andrew J.

AU - Duev, Dmitry A.

AU - Feeney, Michael

AU - Graham, Matthew J.

AU - Kaplan, David L.

AU - Laher, Russ R.

AU - Littlefair, S. P.

AU - Masci, Frank J.

AU - Riddle, Reed

AU - Rusholme, Ben

AU - Serabyn, Eugene

AU - Smith, Roger M.

AU - Shupe, David L.

AU - Soumagnac, Maayane T.

PY - 2020/3/1

Y1 - 2020/3/1

N2 - We report the discovery of the first short-period binary in which a hot subdwarf star (sdOB) filled its Roche lobe and started mass transfer to its companion. The object was discovered as part of a dedicated high-cadence survey of the Galactic plane named the Zwicky Transient Facility and exhibits a period of P = 39.3401(1) minutes, making it the most compact hot subdwarf binary currently known. Spectroscopic observations are consistent with an intermediate He-sdOB star with an effective temperature of Teff = 42,400 ± 300 K and a surface gravity of logg = 5.77 ± 0.05. A high signal-to-noise ratio GTC+HiPERCAM light curve is dominated by the ellipsoidal deformation of the sdOB star and an eclipse of the sdOB by an accretion disk. We infer a low-mass hot subdwarf donor with a mass M sdOB = 0.337 ± 0.015 M⊙ and a white dwarf accretor with a mass M WD = 0.545 ± 0.020 M⊙. Theoretical binary modeling indicates the hot subdwarf formed during a common envelope phase when a 2.5-2.8 M⊙ star lost its envelope when crossing the Hertzsprung gap. To match its current Porb, Teff, logg, and masses, we estimate a post-common envelope period of Porb ≈ 150 minutes and find that the sdOB star is currently undergoing hydrogen shell burning. We estimate that the hot subdwarf will become a white dwarf with a thick helium layer of ≈0.1 M⊙, merge with its carbon/oxygen white dwarf companion after ≈17 Myr, and presumably explode as a thermonuclear supernova or form an R CrB star.

AB - We report the discovery of the first short-period binary in which a hot subdwarf star (sdOB) filled its Roche lobe and started mass transfer to its companion. The object was discovered as part of a dedicated high-cadence survey of the Galactic plane named the Zwicky Transient Facility and exhibits a period of P = 39.3401(1) minutes, making it the most compact hot subdwarf binary currently known. Spectroscopic observations are consistent with an intermediate He-sdOB star with an effective temperature of Teff = 42,400 ± 300 K and a surface gravity of logg = 5.77 ± 0.05. A high signal-to-noise ratio GTC+HiPERCAM light curve is dominated by the ellipsoidal deformation of the sdOB star and an eclipse of the sdOB by an accretion disk. We infer a low-mass hot subdwarf donor with a mass M sdOB = 0.337 ± 0.015 M⊙ and a white dwarf accretor with a mass M WD = 0.545 ± 0.020 M⊙. Theoretical binary modeling indicates the hot subdwarf formed during a common envelope phase when a 2.5-2.8 M⊙ star lost its envelope when crossing the Hertzsprung gap. To match its current Porb, Teff, logg, and masses, we estimate a post-common envelope period of Porb ≈ 150 minutes and find that the sdOB star is currently undergoing hydrogen shell burning. We estimate that the hot subdwarf will become a white dwarf with a thick helium layer of ≈0.1 M⊙, merge with its carbon/oxygen white dwarf companion after ≈17 Myr, and presumably explode as a thermonuclear supernova or form an R CrB star.

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U2 - 10.3847/1538-4357/ab72ff

DO - 10.3847/1538-4357/ab72ff

M3 - مقالة

SN - 0004-637X

VL - 891

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 1

M1 - 45

ER -

The First Ultracompact Roche Lobe-Filling Hot Subdwarf Binary

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