Volume 538, February 2012
|Number of page(s)||7|
|Section||Interstellar and circumstellar matter|
|Published online||08 February 2012|
Structure of the pre-outburst accretion disk in SS Cygni
Institute of Astronomy of the Russian Academy of Sciences,
48, Pyatnitskaya str.,
2 INAF – Istituto di Astrofisica Spaziale e Fisica Cosmica – Roma, Area di Ricerca di Tor Vergata, via del Fosso del Cavaliere 100, 00133 Roma, Italy
3 INAF Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy
Received: 15 December 2010
Accepted: 10 November 2011
We present results of spectroscopic observations of SS Cygni performed at the 1.5 m telescope of the Loiano Observatory in June 2009, three days before a long outburst. Using results of these observations, we computed Doppler tomograms in three Balmer lines Hβ, Hγ, and Hδ. Analyzing the tomograms, we identified gas dynamic features existing in the system. It is shown that in the pre-outburst disk a number of shock waves exist. These waves are “hot line” a wave produced by the interaction between the circum-disk halo and the stream from the inner Lagrangian point L1, and two arms of the spiral tidal shock and bow shock caused by the motion of the accretor and disk in the gas of the circum-binary envelope. We also found that before the outburst the density and size of the disk increase.
Key words: techniques: spectroscopic / accretion, accretion disks / stars: dwarf novae / stars: individual: SS Cygni / novae, cataclysmic variables
© ESO, 2012
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