TY - JOUR
T1 - R Coronae Borealis stars in M31 from the Palomar Transient Factory
AU - Tang, Sumin
AU - Cao, Yi
AU - Bildsten, Lars
AU - Nugent, Peter
AU - Bellm, Eric
AU - Kulkarni, Shrinivas R.
AU - Laher, Russ
AU - Levitan, David
AU - Masci, Frank
AU - Ofek, Eran O.
AU - Prince, Thomas A.
AU - Sesar, Branimir
AU - Surace, Jason
N1 - National Science Foundation [PHY 11-25915, AST 11-09174]; Israeli Ministry of ScienceWe thank Geoff Clayton for pointing out the similarities between PTF-M31-RCB-1 (2) and RY Sgr (V854 Cen), providing spectra of RY Sgr and V854 Cen, and many helpful discussions. We thank the anonymous referee for comments that have helped to improve this Letter. We thank Sagi Ben-Ami and Dong Xu for reducing two candidate spectra, and Adam Miller for helpful discussion. This work was supported by the National Science Foundation under grants PHY 11-25915 and AST 11-09174. E.O.O. is incumbent of the Arye Dissentshik career development chair and is grateful to support by a grant from the Israeli Ministry of Science.
PY - 2013/4/20
Y1 - 2013/4/20
N2 - 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 ≈ 21-22 mag), these RCB stars have R ≈ 19.5-20.5 mag at maximum light, corresponding to MR = -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.
AB - 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 ≈ 21-22 mag), these RCB stars have R ≈ 19.5-20.5 mag at maximum light, corresponding to MR = -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.
UR - http://www.scopus.com/inward/record.url?scp=84876380069&partnerID=8YFLogxK
U2 - 10.1088/2041-8205/767/2/L23
DO - 10.1088/2041-8205/767/2/L23
M3 - مقالة
SN - 2041-8205
VL - 767
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
IS - 2
M1 - L23
ER -