PTF1 J071912.13+485834.0: An Outbursting AM CVn System Discovered by a Synoptic Survey

Creators: Levitan, David; Fulton, Benjamin J.; Groot, Paul J.; Kulkarni, Shrinivas R.; Ofek, Eran O.; Prince, Thomas A.; Shporer, Avi; Bloom, Joshua S.; Cenko, S. Bradley; Kasliwal, Mansi M.; Law, Nicholas M.; Nugent, Peter E.; Poznanski, Dovi; Quimby, Robert M.; Horesh, Assaf

Abstract

We present extensive photometric and spectroscopic observations of PTF1 J071912.13+485834.0, an outbursting AM CVn system discovered by the Palomar Transient Factory (PTF). AM CVn systems are stellar binaries with some of the smallest separations known and orbital periods ranging from 5 to 65 minutes. They are believed to be composed of a white dwarf accretor and a (semi-)degenerate He-rich donor and are considered to be the helium equivalents of cataclysmic variables (CVs). We have spectroscopically and photometrically identified an orbital period of 26.77 ± 0.02 minutes for PTF1 J071912.13+485834.0 and found a super-outburst recurrence time of greater than 65 days along with the presence of "normal" outbursts—rarely seen in AM CVn systems but well known in super-outbursting CVs. We present a long-term light curve over two super-cycles as well as high-cadence photometry of both outburst and quiescent stages, both of which show clear variability. We also compare both the outburst and quiescent spectra of PTF1 J071912.13+485834.0 to other known AM CVn systems, and use the quiescent phase-resolved spectroscopy to determine the origin of the photometric variability. Finally, we draw parallels between the different subclasses of SU UMa-type CVs and outbursting AM CVn systems. We conclude by predicting that the PTF may more than double the number of outbursting AM CVn systems known, which would greatly increase our understanding of AM CVn systems.

Additional Information

© 2011 The American Astronomical Society. Received 2011 May 9; accepted 2011 July 6; published 2011 September 7. Observations obtained with the Samuel Oschin Telescope at the Palomar Observatory as part of the Palomar Transient Factory project, a scientific collaboration between the California Institute of Technology, Columbia University, Las Cumbres Observatory, the Lawrence Berkeley National Laboratory, the National Energy Research Scientific Computing Center, the University of Oxford, and the Weizmann Institute of Science. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The William Herschel Telescope is operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias. This paper uses observations obtained with facilities of the Las Cumbres Observatory Global Telescope. The Byrne Observatory at Sedgwick (BOS) is operated by the Las Cumbres Observatory Global Telescope Network and is located at the Sedgwick Reserve, a part of the University of California Natural Reserve System. S.B.C. acknowledges generous support from Gary and Cynthia Bengier, the Richard and Rhoda Goldman Fund, National Aeronautics and Space Administration (NASA)/Swift grant NNX10AI21G, NASA/Fermi grant NNX1OA057G, and National Science Foundation (NSF) grant AST–0908886. Facilities: PO:1.2m, PO:1.5m, LCOGT, FTN (Spectral), Hale (DBSP), ING:Herschel (ACAM), Keck:I (LRIS)

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