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Census of R Coronae Borealis Stars. I. Infrared Light Curves from Palomar Gattini IR

Karambelkar, Viraj R. and Kasliwal, Mansi M. and Tisserand, Patrick and De, Kishalay and Anand, Shreya and Ashley, Michael C. B. and Delacroix, Alex and Hankins, Matthew and Jencson, Jacob E. and Lau, Ryan M. and McKenna, Dan and Moore, Anna and Ofek, Eran O. and Smith, Roger M. and Soria, Roberto and Soon, Jamie and Tinyanont, Samaporn and Travouillon, Tony and Yao, Yuhan (2021) Census of R Coronae Borealis Stars. I. Infrared Light Curves from Palomar Gattini IR. Astrophysical Journal, 910 (2). Art. No. 132. ISSN 1538-4357. doi:10.3847/1538-4357/abe5aa. https://resolver.caltech.edu/CaltechAUTHORS:20210204-092715488

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Abstract

We are undertaking the first systematic infrared (IR) census of R Coronae Borealis (RCB) stars in the Milky Way, beginning with IR light curves from the Palomar Gattini IR (PGIR) survey. The PGIR is a 30 cm J-band telescope with a 25 deg² camera that is surveying 18,000 deg² of the northern sky (δ > −28°) at a cadence of 2 days. We present PGIR light curves for 922 RCB candidates selected from a mid-IR color-based catalog. Of these 922, 149 are promising RCB candidates, as they show pulsations or declines similar to RCB stars. The majority of the candidates that are not RCB stars are either long-period variables (LPVs) or RV Tauri stars. We identify IR color-based criteria to better distinguish between RCB stars and LPVs. As part of a pilot spectroscopic run, we obtain NIR spectra for 26 of the 149 promising candidates and spectroscopically confirm 11 new RCB stars. We detect strong He I λ10830 features in the spectra of all RCB stars, likely originating within high-velocity (200–400 km s⁻¹) winds in their atmospheres. Nine of these RCB stars show ¹²C¹⁶O and ¹²C¹⁸O molecular absorption features, suggesting that they are formed through a white dwarf merger. We detect quasiperiodic pulsations in the light curves of five RCB stars. The periods range between 30 and 125 days and likely originate from the strange-mode instability in these stars. Our pilot run results motivate a dedicated IR spectroscopic campaign to classify all RCB candidates.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.3847/1538-4357/abe5aaDOIArticle
https://arxiv.org/abs/2012.11629arXivDiscussion Paper
ORCID:
AuthorORCID
Karambelkar, Viraj R.0000-0003-2758-159X
Kasliwal, Mansi M.0000-0002-5619-4938
Tisserand, Patrick0000-0003-4237-0520
De, Kishalay0000-0002-8989-0542
Anand, Shreya0000-0003-3768-7515
Ashley, Michael C. B.0000-0003-1412-2028
Hankins, Matthew0000-0001-9315-8437
Jencson, Jacob E.0000-0001-5754-4007
Moore, Anna0000-0002-2894-6936
Ofek, Eran O.0000-0002-6786-8774
Smith, Roger M.0000-0001-7062-9726
Soria, Roberto0000-0002-4622-796X
Tinyanont, Samaporn0000-0002-1481-4676
Travouillon, Tony0000-0002-7279-3658
Yao, Yuhan0000-0001-6747-8509
Additional Information:© 2021. The American Astronomical Society. Received 2020 December 19; revised 2021 February 9; accepted 2021 February 10; published 2021 April 5. We thank our referee, Geoff Clayton, for valuable feedback that improved the manuscript. The Palomar Gattini IR (PGIR) is generously funded by Caltech, Australian National University, the Mt. Cuba Foundation, the Heising Simons Foundation, and the Binational Science Foundation. The PGIR is a collaborative project among Caltech, Australian National University, the University of New South Wales, Columbia University, and the Weizmann Institute of Science. M.M.K. acknowledges generous support from the David and Lucile Packard Foundation. J.S. acknowledges the support of an Australian Government Research Training Program (RTP) scholarship. Some of the data presented here were obtained with the 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.
Group:Astronomy Department
Funders:
Funding AgencyGrant Number
CaltechUNSPECIFIED
Australian National UniversityUNSPECIFIED
Mt. Cuba Astronomical FoundationUNSPECIFIED
Heising-Simons FoundationUNSPECIFIED
Binational Science Foundation (USA-Israel)UNSPECIFIED
Weizmann Institute of ScienceUNSPECIFIED
David and Lucile Packard FoundationUNSPECIFIED
Australian Government Research Training ProgramUNSPECIFIED
NASA80HQTR19D0030
Subject Keywords:R Coronae Borealis variable stars; Hydrogen deficient stars; Near infrared astronomy; Time domain astronomy
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: R Coronae Borealis variable stars (1327); Hydrogen deficient stars (769); Near infrared astronomy (1093); Time domain astronomy (2109)
DOI:10.3847/1538-4357/abe5aa
Record Number:CaltechAUTHORS:20210204-092715488
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20210204-092715488
Official Citation:Viraj R. Karambelkar et al 2021 ApJ 910 132
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:107906
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:05 Feb 2021 20:47
Last Modified:14 Apr 2021 14:49

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