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Discovery of a new am CVn system with the kepler satellite

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Fontaine, Gilles, Brassard, Pierre, Green, Elizabeth Melton, Charpinet, Stephane, Dufour, Patrick, Hubený, I., Steeghs, D., Aerts, Conny, Randall, S. K., Bergeron, P. et al.

. (2011) Discovery of a new am CVn system with the kepler satellite. Astrophysical Journal, Volume 726 (Number 2). Article number 92. ISSN 0004-637X

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Official URL: http://dx.doi.org/10.1088/0004-637X/726/2/92

Abstract

We report the discovery of a new AM CVn system on the basis of broadband photometry obtained with the Kepler satellite supplemented by ground-based optical spectroscopy. Initially retained on Kepler target lists as a potential compact pulsator, the blue object SDSS J190817.07+394036.4 (KIC 004547333) has turned out to be a high-state AM CVn star showing the He-dominated spectrum of its accretion disk significantly reddened by interstellar absorption. We constructed new grids of NLTE synthetic spectra for accretion disks in order to analyze our spectroscopic observations. From this analysis, we infer preliminary estimates of the rate of mass transfer, the inclination angle of the disk, and the distance to the system. The AM CVn nature of the system is also evident in the Kepler light curve, from which we extracted 11 secure periodicities. The luminosity variations are dominated by a basic periodicity of 938.507 s, likely to correspond to a superhump modulation. The light curve folded on the period of 938.507 s exhibits a pulse shape that is very similar to the superhump wavefront seen in AM CVn itself, which is a high-state system and the prototype of the class. Our Fourier analysis also suggests the likely presence of a quasi-periodic oscillation similar to those already observed in some high-state AM CVn systems. Furthermore, some very low-frequency, low-amplitude aperiodic photometric activity is likely present, which is in line with what is expected in accreting binary systems. Inspired by previous work, we further looked for and found some intriguing numerical relationships between the 11 secure detected frequencies, in the sense that we can account for all of them in terms of only three basic clocks. This is further evidence in favor of the AM CVn nature of the system.

Item Type:

Journal Article

Subjects:

Q Science > QB Astronomy

Divisions:

Faculty of Science > Physics

Library of Congress Subject Headings (LCSH):

Accretion (Astrophysics), Double stars, White dwarf stars

Journal or Publication Title:

Astrophysical Journal

Publisher:

IOP Publishing

ISSN:

0004-637X

Official Date:

10 January 2011

Dates:

Date	Event
10 January 2011	Published

Volume:

Volume 726

Number:

Number 2

Number of Pages:

Article Number:

Article number 92

Identification Number:

10.1088/0004-637X/726/2/92

Status:

Peer Reviewed

Publication Status:

Published

Access rights to Published version:

Restricted or Subscription Access

Funder:

Natural Sciences and Engineering Research Council of Canada (NSERC), Seventh Framework Programme (European Commission) (FP7), Centre national de la recherche scientifique (France) (CNRS), Centre national d'études spatiales (France) (CNES), National Science Foundation (U.S.) (NSF), Norman Hackerman Advanced Research Program (NHARP), Delaware Asteroseismic Research Center

Grant number:

FP7/2007-2013, 227224 (FP7), AST-0909107 (NSF), 003658-0255-2007 (NHARP), 003658-0252-2009 (NHARP)

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