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Dear Grzegorz, It is very unlikely that V4745 Sgr has dwarf nova outbursts at this stage. The simple explanation for this behaviour is oscillations during the transition phase. The similarity of the oscillations during the transition phase to dwarf nova outbursts has been pointed out by Leibowitz (1993, ApJ, 411, L29), but at this early stage of the nova outburst the disc is very hot and thermally stable thus disc instabilities similar to dwarf nova outbursts cannot be the cause for the oscillations. In the past years several other suggestions for the transition phase have been submitted, but this issue is still controversial. Regards, Alon ----------------------------------------------------------------------- Dr. Alon Retter Tel. (work) +61-2-9351-4058 School of Physics Fax (work) +61-2-9351-7726 University of Sydney ------------------------------------------- Sydney, 2006 "As a scientist I don't believe myself, so Australia why should I believe you?" (A.R. 1965-2085) http://vsnet.physics.usyd.edu.au/~retter/ ----------------------------------------------------------------------- On Tue, 24 Jun 2003, Grzegorz Pojmanski wrote: > Dear VSNETers, > > V4745 Sgr has stared its 3-d major re-brightening since its > nova-outburst on Apr, 10. > > Similarly as during the second major re-brightening, low amplitude > (0.02 > -0.05) modulation with period ~0.2 (>=0.1 tonight?) is clearly visible > on the rising branch (some traces of it are also visible on the > descending branch and before the third onset). > > At this point resemblance to the dwarf novae is striking and one > plausible explanation is that (for the first time?) we see > disk-instability induced outbursts overlaid on the declining branch of > the nova light curve. > > Continuous photometric monitoring would be required to > investigate hump period and its variation, > as well as time resolved spectroscopy would be of great importance. > > ASAS data for V4745 (light curve + zoomed parts) area available at: > http://vsnet.astrouw.edu.pl/cgi-asas/asas_V4745SGR > > Regards, Grzegorz Pojmanski, ASAS > >
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