J/AJ/156/150ivo://CDS.VizieR/J/AJ/156/150doi:10.26093/cds/vizier.51560150CDSStiller R.A.Littlefield C.Garnavich P.Wood C.Hambsch F.-J.Myers G.2019-04-08T13:07:45Z2019-04-01T14:13:16ZCDS support team

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

cds-question@unistra.frcataclysmic-variable-starsvariable-starsdwarf-starsccd-photometryThe unique binary AR Scorpii consists of an asynchronously rotating, magnetized white dwarf (WD) that interacts with its red-dwarf companion to produce a large-amplitude, highly coherent pulsation every 1.97 minutes. Over the course of two years, we obtained 39 hours of time-resolved, optical photometry of AR Sco at a typical cadence of 5 s to study this pulsation. We find that it undergoes significant changes across the binary orbital period and that its amplitude, phase, and waveform all vary as a function of orbital phase. We show that these variations can be explained by constructive and destructive interference between two periodic, double-peaked signals: the spin-orbit beat pulse, and a weaker WD spin pulse. Modeling of the light curve indicates that in the optical, the amplitude of the primary spin pulse is 50% of the primary beat amplitude, while the secondary maxima of the beat and spin pulses have similar amplitudes. Finally, we use our timings of the beat pulses to confirm the presence of the disputed spin-down of the WD. We measure a beat-frequency derivative of {nu}=(-5.14+/-0.32)x10^-17^ Hz/s and show that this is attributable to the spin-down of the WD. This value is approximately twice as large as the estimate from Marsh et al. but is nevertheless consistent with the constraints established in Potter & Buckley (2018MNRAS.478L..78P). Our precise measurement of the spin-down rate confirms that the decaying rotational energy of the magnetized WD is sufficient to power the excess electromagnetic radiation emitted by the binary.2018AJ....156..150Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/156/150CatalogResearchIsServedByTAP VizieR generic servicerelated-toV/123 : Catalog of Cataclysmic Variables (Downes+ 2001-2006)J/A+A/611/A66 : AR Sco VLA radio observations (Stanway+, 2018)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/156/150https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/156/150http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/156/150https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/156/150https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/156/150http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/156/150GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapdefaultJ/AJ/156/150/fig1SLKT light curve of AR ScorecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBJDBarycentric Julian Date; TDBdtime.epochdoublemag[-0.078/3.423] Differential, unfiltered magnitude (1)magphot.magfloate_mag[0.012/0.541] 1{sigma} uncertainty in magmagstat.error;phot.magfloatJ/AJ/156/150/table3Beat-pulse timingsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintEpoch[-251505/234767] Beat cycle count (1)meta.numberintTmaxTime of pulse maximum (BJD_TDB) (2)dtime.epochdoublee_Tmax[7e-06/0.000212] 1{sigma} uncertainty in Tmaxdstat.errordoubleTmax-corCorrected time of pulse maximum (BJD_TDB) (3)dtime.epochdouble