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Discovery of a new AM CVn system with the Kepler satellite

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Discovery of a new AM CVn system with the Kepler satellite

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Título Discovery of a new AM CVn system with the Kepler satellite
Autor Fontaine, Gilles
Brassard, P.
Green, Elisabeth M.
Charpinet, Stéphane
Dufour, Patrick
Hubeny, Ivan
Steeghs, Danny
Aerts, Conny
Randall, S. K.
Bergeron, Pierre
Guvenen, B.
O'Malley, C. J.
Van Grootel, Valérie
Ostensen, Roy
Bloemen, Steven
Silvotti, Roberto
Howell, Steve
Baran, Andrzej
Kepler, Souza Oliveira
Marsh, Tom
Montgomery, Michael Houston
Oreiro, Raquel
Provencal, Judith L.
Telting, John
Winget, Donald Earl
Zima, Wolfgang
Christensen-Dalsgaard, Jorgen
Kjeldsen, Hans
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.
Contido em The astrophysical journal. Bristol. Vol. 726, no. 2 (Jan. 2011), 92, 11 p.
Assunto Acreção
Anãs brancas
Discos de acrecao
Nucleo galatico
[en] Accretion, accretion disks
[en] Binaries: close
[en] Stars: individual (SDSS J190817.07+394036.4, KIC 004547333)
[en] White dwarfs
Origem Estrangeiro
Tipo Artigo de periódico
URI http://hdl.handle.net/10183/108973
Arquivos Descrição Formato
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