5 research outputs found
SDSS J210014.12+004446.0 - dwarf nova with negative and positive superhumps
We report the results of 67h of CCD photometry of the recently discovered
dwarf nova SDSS J210014.12+004446.0. The data were obtained on 24 nights
spanning a month. During this time we observed four ordinary outbursts lasting
about 2-3 days and reaching an amplitude of ~1.7 mag. On all nights our light
curve revealed persistent modulation with the stable period of 0.081088(3)
days. These humps were already observed on one night by Tramposch et al.
(2005), who additionally observed superhumps during a superoutburst.
Remarkably, from scant evidence at their disposal they were able to discern
them as negative and positive (common) superhumps, respectively. Our period in
quiescence clearly different from their superhump period confirmed this. Our
discovery of an additional modulation, attributed by us to the orbital wave,
completes the overall picture. Lack of superhumps in our data indicates that
all eruptions we observed were ordinary outbursts. The earlier observation of
the superhumps combined with the presence of the ordinary outbursts in our data
enables classification of SDSS J2100 as an active SU UMa dwarf nova.
Additionally, we have promoted SDSS J2100 to the group of cataclysmic variables
exhibiting three periodic modulations of light from their accretion discs. We
updated available information on positive and negative superhumps and thus
provided enhanced evidence that their properties are strongly correlated
mutually as well as with the orbital period. By recourse to these relations we
were able to remove an alias ambiguity and to identify the orbital period of
SDSS J2100 of 0.083304(6) days. SDSS J21000 is only third SU UMa dwarf nova
showing both positive and negative superhumps. Their respective period excess
and deficit equal to 4.99(3)% and -2.660(8)%, yielding the mass ratio q=0.24.Comment: 10 pages, 9 figures, accepted for publication in MNRA