J/ApJ/955/150ivo://CDS.VizieR/J/ApJ/955/150CDSGreiveldinger A.Garnavich P.Littlefield C.Kennedy M.R.,Halpern J.P.Thorstensen J.R.Szkody P.Oksanen A.Boyle R.S.2026-01-07T12:42:40Z2026-01-07T13:25:36ZCDS support team

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

cds-question@unistra.frvariable-starsphotometryvisible-astronomyWe identify a previously undetected periodicity at a frequency of 49.08{\pm}0.01days^-1^ (period of 29.34{\pm}0.01 minutes) during a super-outburst of V844 Her observed by TESS. V844 Her is an SU UMa type cataclysmic variable with an orbital period of 78.69 minutes, near the period minimum. The frequency of this new signal is constant in contrast to the superhump oscillations commonly seen in SU UMa outbursts. We searched without success for oscillations during quiescence using MDM, TESS, and XMM-Newton data. The lack of a periodic signal in the XMM light curve and the relatively low X-ray luminosity of V844 Her suggest that it is not a typical IP. We consider the possibility that the 29-minute signal is the result of super-Nyquist sampling of a dwarf nova oscillation with a period near the 2-minute cadence of the TESS data. Our analysis of archival AAVSO photometry from a 2006 super-outburst supports the existence of a 29-minute oscillation, although a published study of an earlier super-outburst did not detect the signal. We compare the X-ray properties of V844 Her with short orbital period intermediate polars (IP), V1025 Cen and DW Cnc. We conclude that the new signal is a real photometric oscillation coming from the V844 Her system and that it is unlikely to be an aliased high-frequency oscillation. The steady frequency of the new signal suggests that its origin is related to an asynchronously rotating white dwarf in V844 Her, although the precise mechanism producing the flux variations remains unclear.2023ApJ...955..150Ghttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/955/150CatalogResearchIsServedByTAP VizieR generic servicerelated-toB/cb : Cataclysmic Binaries, LMXBs, and related objects (Ritter+, 2004)V/123 : Catalog of Cataclysmic Variables (Downes+ 2001-2006)I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)I/358 : Gaia DR3 Part 4. Variability (Gaia Collaboration, 2022)J/ApJ/565/511 : Cataclysmic variables in the 2MASS 2IDR (Hoard+, 2002)J/other/NewA/13.133 : 2MASS photometry of cataclysmic variables (Ak+, 2008)J/other/JAD/15.1 : Time-series of 9 cataclysmic variables (Papadaki+, 2009)J/ApJ/696/870 : Catalina Real-time Transient Survey (CRTS) (Drake+, 2009)J/MNRAS/402/436 : Dwarf novae in SDSS, GALEX and astrom. cat. (Wils+, 2010)J/AJ/142/181 : CVs from SDSS. VIII. The final year (Szkody+, 2011)J/PASJ/64/63 : Dwarf novae characterization using SDSS colors (Kato+, 2012)J/ApJ/788/48 : X-ray through NIR photometry of NGC 2617 (Shappee+, 2014)J/MNRAS/441/1186 : Cataclysmic variables from CRTS (Drake+, 2014)J/PASJ/68/65 : Superhumps in SU UMa-type dwarf novae (Kato+, 2016)J/MNRAS/460/2526 : Dwarf novae outbursts properties (Otulakowska-Hypka+, 2016)J/MNRAS/492/L40 : Disentangling CVs in Gaia DR2 (Abril+, 2020)J/MNRAS/502/5668 : Superoutburst of 206 SU UMa-type dwarf novae (Vogt+, 2021)J/MNRAS/504/2420 : Close white dwarf binaries - Ref. samples (Inight+, 2021)J/ApJ/910/120 : Dwarf nova outbursts detected by ASAS-SN (Kawash+, 2021)J/ApJ/938/46 : CV orb. periods from Gaia phot. (Abrahams+, 2022)J/AJ/165/163 : Cataclysmic variables in the Gaia era (Canbay+, 2023)J/MNRAS/524/4867 : CVs from SDSS (Inight+, 2023)J/A+A/675/A195 : ZTF DR11 classif. in ZTF/4MOST sky (Sanchez-Saez+, 2023)J/A+A/687/A250 : STONKS Multi-Mission X-ray Catalog (Quintin+, 2024)J/MNRAS/536/1057 : CVs from SDSS-V (Inight+, 2025)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/955/150https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/955/150http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/955/150https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/955/150https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/955/150http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/955/150GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/ApJ/955/150/fig10The MDM lightcurves of V844 Her from the four individual nightsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBJDBarycentric Julian Daydtime.epochdoubleGG420mag[17.74/18.23] Magnitude in longpass GG420 filtermagphot.mag;em.opt.Bdoublee_GG420mag[0.012/0.11] Uncertainty in GG420magmagstat.error;phot.mag;em.opt.Bdouble