A spectroscopic study of V603 Aquilae: stellar parameters and continuum–line variations

A time-resolved spectroscopic study of V603 Aql (Nova Aquilae 1918) is presented. An orbital period of Porb=01385±00002, consistent with previous results, and a radial velocity semi-amplitude of K=20±3 km s−1 are obtained from the radial velocity variations of the Hβ emission line. Similar K values are also found in Hγ, Hδ, and He i emission lines. Using the measured FWHM of the Hβ line and assuming that the derived semi-amplitude is that of the white dwarf, we deduce a most likely mass ratio of q=0.24±0.05 and stellar masses of M2=0.29±0.04 M⊙ and M1=1.2±0.2 M⊙ for the secondary and primary (the white dwarf) star, respectively. The dynamical solution also indicates a very low orbital inclination, i=13°±2°. We find that the continuum and line variations are modulated with both the positive and the negative superhump periods, indicating that they arise from similar regions of the accretion disc. Moreover, we find, for the first time from spectroscopy, evidence of negative superhumps in addition to the positive superhumps. Positive superhumps are explained within the disc instability model as caused by an eccentric disc surrounding the white dwarf, which is precessing (apsidal advance) because of tidal instabilities, causing the observed positive superhumps. A nodal precession in the accretion disc is currently believed to be the cause of the observed negative superhumps. The low value of q is consistent with the expected value for systems that show superhumps, in accordance with the eccentric disc model. We find no evidence of periodicity associated with the spin period.

[1]  Cecilia Payne-Gaposchkin,et al.  The Galactic Novae , 1958 .

[2]  P. Szkody,et al.  A dynamical model for the dwarf nova AH Herculis , 1986 .

[3]  J. B. Oke.  Faint Spectrophotometric Standard Stars , 1990 .

[4]  J. Patterson,et al.  SUPERHUMPS IN CATACLYSMIC BINARIES. XI. V603 AQUILAE REVISITED , 1997 .

[5]  K. Horne,et al.  Emission-line mapping of the dwarf nova IP Pegasi in outburst and quiescence , 1990 .

[6]  K. Horne,et al.  Images of accretion discs – II. Doppler tomography , 1988 .

[7]  S. Kiyota,et al.  Superhumps and Accretion Disk Precession in TT Arietis , 1998 .

[8]  H. Duerbeck.  The final decline of novae and the hibernation hypothesis , 1992 .

[9]  J. Drew,et al.  Boundary-layer temperatures in high accretion rate cataclysmic variables , 1991 .

[10]  Edwin E. Salpeter,et al.  MODELS FOR ZERO-TEMPERATURE STARS , 1961 .

[11]  J. Patterson,et al.  On the Mass-Radius Relation of Late M Dwarfs , 1990 .

[12]  K. Horne,et al.  AN OPTIMAL EXTRACTION ALGORITHM FOR CCD SPECTROSCOPY. , 1986 .

[13]  G. Ferland,et al.  Physical Conditions in the Accretion Disk of V603 Aquilae , 1982 .

[14]  R. Whitehurst.  Eccentric-mode excitation of accretion discs. , 1994 .

[15]  A. A. Boyarchuk,et al.  Structure of envelopes ejected by Novae , 1970 .

[16]  Simulations of superhumps and superoutbursts , 1997, astro-ph/9710233.

[17]  E. Leibowitz,et al.  Predicting the future of superhumps in classical nova systems , 1998, astro-ph/9803081.

[18]  R. Webbink,et al.  SPECTROSCOPY AND PHOTOMETRY OF THE DWARF NOVA BZ UMA AND THE CV LINE-WIDTH/K, MASS-RATIO RELATION , 1994 .

[19]  D. Schneider,et al.  The magnetic maw of 2A 0311-22.7. , 1980 .

[20]  J. Scargle.  Studies in astronomical time series analysis. II - Statistical aspects of spectral analysis of unevenly spaced data , 1982 .

[21]  J. Thorstensen,et al.  A Photometric and Spectroscopic Study of the Cataclysmic Variable SX Leonis Minoris in Quiescence and Superoutburst , 1998 .

[22]  J. Patterson,et al.  The 1991 V603 Aquilae campaign - Superhumps and P-dots , 1993 .

[23]  A. Shafter.  Radial velocity studies of cataclysmic binaries. I. KR Aurigae. , 1983 .

[24]  Y. Osaki.  DWARF-NOVA OUTBURSTS , 1996 .

[25]  R. P. Kraft.  Binary Stars among Cataclysmic Variables. III. Ten Old Novae. , 1964 .

[26]  V. Dhillon,et al.  The mass of the white dwarf in the old nova BT Mon , 1997 .

[27]  J. Patterson.  Late Evolution of Cataclysmic Variables , 1998 .