J/A+A/497/437ivo://CDS.VizieR/J/A+A/497/437doi:10.26093/cds/vizier.34970437CDSRutkowski A.Olech A.Wisniewski M.Pietrukowicz P.Pala J.Poleski R.2017-06-26T11:50:03Z2009-07-12T16:02:40ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frnovaecataclysmic-variable-starsapparent-magnitudeWe report an analysis of photometric behaviour of DI UMa, an extremely active dwarf nova. The observational campaign (completed in 2007) covers five superoutbursts and four normal outbursts. We examined principal parameters of the system to understand peculiarities of DI UMa, and other active cataclysmic variables. Based on precise photometric measurements, temporal light curve behaviour, O-C analysis, and power spectrum analysis, we investigated physical parameters of the system. We found that the period of the supercycle now equals 31.45+/-0.3days. Observations during superoutbursts infer that the period of superhumps equals P_sh_=0.055318(11)days (79.66+/-0.02min). During quiescence, the light curve reveals a modulation of period P_orb_=0.054579(6)days (78.59+/-0.01min), which we interpret as the orbital period of the binary system. The values obtained allowed us to determine a fractional period excess of 1.35+/-0.02%, which is surprisingly small compared to the usual value for dwarf novae (2%-5%). A detailed O-C analysis was performed for two superoutbursts with the most comprehensive coverage. In both cases, we detected an increase in the superhump period with a mean rate of (dP/dt)/P_sh_=4.4(1.0)x10^-5^. Based on these measurements, we confirm that DI UMa is probably a period bouncer, an old system that reached its period minimum a long time ago, has a secondary that became a degenerate brown dwarf, the entire system evolving now toward longer periods. DI UMa is an extremely interesting object because we know only one more active ER UMa star with similar characteristics (IX Dra).2009A&A...497..437Rhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/497/437CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/497/437https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/497/437http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/497/437https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/497/437https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/497/437http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/497/437GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/A+A/497/437/VphotV photometry of DI UMarecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintTelTelescope size (0.5m or 0.3m)dmphys.size;instr.telcharJDJulian Datedtime.epochdoubleVmagV magnitudemagphot.mag;em.opt.Vfloate_Vmagrms uncertainty on Vmagmagstat.error;phot.mag;em.opt.Vfloat