We thank the anonymous referee for useful suggestions that improved this paper. V.K. thanks Sunny Wong and Yashvi Sharma for useful discussions. Palomar Gattini-IR (PGIR) is generously funded by Caltech, Australian National University, the Mt Cuba Foundation, the Heising Simons Foundation, the Bi- national Science Foundation. PGIR is a collaborative project among Caltech, Australian National University, University of New South Wales, Columbia University and the Weizmann Institute of Science. M.M.K. acknowledges generous support from the David and Lucille Packard Foundation. J. Soon acknowledges the support of an Australian Government Research Training Program (RTP) scholarship. Some of the data presented here were obtained with Visiting Astronomer facility at the Infrared Telescope Facility, which is operated by the University of Hawaii under contract 80HQTR19D0030 with the National Aeronautics and Space Administration. This work was supported, in part, by the National Science Foundation through grant PHY-2309135 to the Kavli Institute for Theoretical Physics, and by the Gordon and Betty Moore Foundation through grant GBMF5076.
An Infrared Census of R Coronae Borealis Stars II—Spectroscopic Classifications and Implications for the Rate of Low-mass White Dwarf Mergers
Creators
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Karambelkar, Viraj R.1
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Kasliwal, Mansi M.1
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Tisserand, Patrick2, 3
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Anand, Shreya1
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Ashley, Michael C. B.4
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Bildsten, Lars5, 6
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Clayton, Geoffrey C.7, 8
- Crawford, Courtney C.9
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De, Kishalay10
- Earley, Nicholas1
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Hankins, Matthew J.11
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Hall, Xander1
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Lamberts, Astrid12, 13
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Lau, Ryan M.14
- McKenna, Dan1
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Moore, Anna15
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Ofek, Eran O.16
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Smith, Roger M.1
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Soria, Roberto17, 18, 9
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Soon, Jamie15
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Travouillon, Tony15
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1.
California Institute of Technology
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2.
Institut d'Astrophysique de Paris
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3.
Sorbonne University
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4.
UNSW Sydney
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5.
University of California, Santa Barbara
- 6. Kavli Institute for Theoretical Physics, University of California, Santa Barbara, CA 93106, USA
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7.
Louisiana State University
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8.
Space Science Institute
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9.
University of Sydney
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10.
Massachusetts Institute of Technology
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11.
Arkansas Tech University
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12.
Observatoire de la Côte d'Azur
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13.
Lagrange Laboratory
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14.
NOIRLab
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15.
Australian National University
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16.
Weizmann Institute of Science
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17.
University of Chinese Academy of Sciences
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18.
Osservatorio Astrofisico di Torino
Abstract
We present results from a systematic infrared (IR) census of R Coronae Borealis (RCB) stars in the Milky Way, using data from the Palomar Gattini IR (PGIR) survey. RCB stars are dusty, erratic variable stars presumably formed from the merger of a He-core and a CO-core white dwarf (WD). PGIR is a 30 cm J-band telescope with a 25 deg2 camera that surveys 18,000 deg2 of the northern sky (δ > −28°) at a cadence of 2 days. Using PGIR J-band lightcurves for ∼60 million stars together with mid-IR colors from WISE, we selected a sample of 530 candidate RCB stars. We obtained near-IR spectra for these candidates and identified 53 RCB stars in our sample. Accounting for our selection criteria, we find that there are a total of ≈ 350(−100)^(+150) RCB stars in the Milky Way. Assuming typical RCB lifetimes, this corresponds to an RCB formation rate of 0.8–5 × 10−3 yr−1, consistent with observational and theoretical estimates of the He-CO WD merger rate. We searched for quasi-periodic pulsations in the PGIR lightcurves of RCB stars and present pulsation periods for 16 RCB stars. We also examined high-cadenced TESS lightcurves for RCB and the chemically similar, but dustless hydrogen-deficient carbon (dLHdC) stars. We find that dLHdC stars show variations on timescales shorter than RCB stars, suggesting that they may have lower masses than RCB stars. Finally, we identified 3 new spectroscopically confirmed and 12 candidate Galactic DY Per type stars—believed to be colder cousins of RCB star—doubling the sample of Galactic DY Per type stars.
Copyright and License
© 2024. The Author(s). Published by IOP Publishing Ltd on behalf of the Astronomical Society of the Pacific (ASP). All rights reserved. Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Acknowledgement
Data Availability
The PGIR J-band lightcurves of all 1215 candidates, lightcurves of new RCB stars, NIR spectra of all 453 sources, spectroscopic classifications of all 453 sources (Table 2) and updated priorities of the T20 candidates (Table 1) are publicly available at Zenodo at 10.5281/zenodo.12683154.
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Karambelkar_2024_PASP_136_084201.pdf
Additional details
Related works
- Is new version of
- Discussion Paper: arXiv:2407.08653 (arXiv)
Funding
- California Institute of Technology
- Australian National University
- Mt. Cuba Astronomical Foundation
- Heising-Simons Foundation
- United States-Israel Binational Science Foundation
- David and Lucile Packard Foundation
- Australian Government Research Training Program
- National Aeronautics and Space Administration
- 80HQTR19D0030
- National Science Foundation
- PHY-2309135
- Gordon and Betty Moore Foundation
- GBMF5076
Dates
- Available
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2024-08-05Published
Caltech Custom Metadata
- Caltech groups
- Palomar Observatory , Astronomy Department , Division of Physics, Mathematics and Astronomy (PMA)
- Publication Status
- Published