Reply To: CG Dra: a VSS campaign

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Maxim Usatov

Was able to make a few points from Mayhill, NM yesterday and time the return to quiescence. Using rearranged equation from Osaki (1974), I have estimated the distance of the bright spot, r_spot, from the primary star – see attached.

Eclipse 24 starts after the previous outburst, so the r_spot decreases during the quiescence. Then, the star luminosity begins to rise, however, r_spot remains at ~12-13 white dwarf radii. The bright spot distance begins to increase up to 26 WD radii when the system is already approximately a day at near-peak outburst luminosity, and then begins to decline as the star begins to fade. So, this shows r_spot change follows the change in the luminosity. With U Gem, according to a chart in Hellier’s book (p. 59), U Gem’s disk begins to increase at the onset of the outburst and reaches peak size at ~ 10 days after the outburst. Disk expanding during the outburst, however, not before, is expected.