R CORONAE BOREALIS STARS IN M31 FROM THE PALOMAR TRANSIENT FACTORY

Journal Article · Sat Apr 20 00:00:00 EDT 2013 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/767/2/L23· OSTI ID:22130737

Sumin, Tang; Bildsten, Lars ^[1]; Yi, Cao; Bellm, Eric; Kulkarni, Shrinivas R.; Levitan, David; Prince, Thomas A.; Sesar, Branimir ^[2]; Nugent, Peter ^[3]; Laher, Russ; Surace, Jason ^[4]; Masci, Frank ^[5]; Ofek, Eran O. ^[6]

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1. Kavli Institute for Theoretical Physics, University of California, Santa Barbara, CA 93106 (United States)
2. Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States)
3. Computational Cosmology Center, Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, CA 94720 (United States)
4. Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States)
5. Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States)
6. Benoziyo Center for Astrophysics and the Helen Kimmel Center for Planetary Science, Weizmann Institute of Science, 76100 Rehovot (Israel)

We report the discovery of R Coronae Borealis (RCB) stars in the Andromeda galaxy (M31) using the Palomar Transient Factory (PTF). RCB stars are rare hydrogen-deficient, carbon-rich supergiant variables, most likely the merger products of two white dwarfs. These new RCBs, including two confirmed ones and two candidates, are the first to be found beyond the Milky Way and the Magellanic Clouds. All of M31 RCBs showed >1.5 mag irregular declines over timescales of weeks to months. Due to the limiting magnitude of our data (R Almost-Equal-To 21-22 mag), these RCB stars have R Almost-Equal-To 19.5-20.5 mag at maximum light, corresponding to M{sub R} = -4 to -5, making them some of the most luminous RCBs known. Spectra of two objects show that they are warm RCBs, similar to the Milky Way RCBs RY Sgr and V854 Cen. We consider these results, derived from a pilot study of M31 variables, as an important proof-of-concept for the study of rare bright variables in nearby galaxies with the PTF or other synoptic surveys.

• OSTI ID: 22130737
• Journal Information: Astrophysical Journal Letters, Vol. 767, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
CARBON
CARBON STARS
MAGELLANIC CLOUDS
MILKY WAY
SPECTRA
TRANSIENTS
WHITE DWARF STARS