Dwarf novae in the Hamburg Quasar Survey: Rarer than expected

Abstract

We report the discovery of five new dwarf novae from the Hamburg Quasar Survey (HQS), and discuss the properties of the sample of dwarf novae in the HQS. The orbital periods of the new dwarf novae are ~105.1 min or ~109.9 min, 114.3+-2.7 min, 92.66+-0.17 min, 272.317+-0.001 min, 258.02+-0.56 min for HS0417+7445, HS1016+3412, HS1340+1524, HS1857+7127, and HS2214+2845, respectively. HS1857+7127 is found to be partially eclipsing. In HS2214+2845 the secondary star of spectral type M3+-1 is clearly detected, and we estimate the distance to the system to be d=390+-40 pc. We recorded one superoutburst of the SU UMa system HS0417+7445. HS1016+3412 and HS1340+1524 have rare outbursts, and their subtype is yet undetermined. HS1857+7127 frequently varies in brightness and may be a Z Cam-type dwarf nova. HS2214+2845 is a U Gem-type dwarf nova with a most likely cycle length of 71 d. To date, 14 new dwarf novae have been identified in the HQS. The ratio of short-period (<3 h) to long-period (>3 h) systems of this sample is 1.3, much smaller compared to the ratio of 2.7 found for all known dwarf novae. The HQS dwarf novae display typically infrequent or low-amplitude outburst activity, underlining the strength of spectroscopic selection in identifying new CVs independently of their variability. The spectroscopic properties of short-period CVs in the HQS suggest that most of them are still evolving towards the minimum period. Their total number agrees with the predictions of population models within an order of magnitude. However, the bulk of all CVs is predicted to have evolved past the minimum period, and those systems remain unidentified. Those post-bounce systems may have markedly weaker Hbeta emission lines compared to the average known short-period CVs, and probably undergo no or extremely rare outbursts.

arXiv commentaccepted for publication in A&A, 17 pages, 18 figures, low-quality figures to comply with astro-ph size limit

References in corpus (31)

• The USNO-B Catalog
• Catalogue of cataclysmic binaries, low-mass X-ray binaries and related objects (Seventh edition)
• An Exploration of the Paradigm for the 2-3 Hour Period Gap in Cataclysmic Variables
• Superhumps in Cataclysmic Binaries. XXV. q_crit, epsilon(q), and Mass-Radius
• Brown Dwarfs and the Cataclysmic Variable Period Minimum
• The 2001 Superoutburst of WZ Sagittae
• Cataclysmic Variables: An Empirical Angular Momentum Loss Prescription From Open Cluster Data
• Measuring White Dwarf Accretion Rates via their Effective Temperatures
• HS2331+3905: The cataclysmic variable that has it all
• Far-ultraviolet Spectroscopy of Magnetic Cataclysmic Variables
• Blunting the Spike: the CV Minimum Period
• Superhumps in Cataclysmic Binaries. XXIV. Twenty More Dwarf Novae
• The Dwarf Novae of Shortest Period
• HS2237+8154: On the onset of mass transfer or entering the period gap?
• The accreting white dwarfs in BW Scl, BC UMa and SW UMa
• Phase-resolved HST/STIS spectroscopy of the exposed white dwarf in the high-field polar AR UMa
• HS0139+0559, HS0229+8016, HS0506+7725 and HS0642+5049: Four new long-period cataclysmic variables
• Rapid Oscillations in Cataclysmic Variables. XVI. DW Cancri
• DW Cancri: a magnetic VY Scl star with an orbital period of 86 minutes
• Distortion of secondaries in semi-detached binaries and the cataclysmic variable period minimum
• The minimum period problem in cataclysmic variables
• Spectroscopy and orbital periods of four cataclysmic variable stars
• HS 0943+1404, a true intermediate polar
• Detection of the white dwarf and the secondary star in the new SU UMa dwarf nova HS 2219+1824
• Two X-Ray Bright Cataclysmic Variables with Unusual Activities: GZ Cnc and NSV 10934
• Time-resolved photometry and spectroscopy of the new deeply-eclipsing SW Sextantis star HS 0728+6738
• A 150MG magnetic white dwarf in the cataclysmic variable RX J1554.2+2721
• GZ Cancri: a cataclysmic variable at the lower edge of the period gap
• On the secondary star of the cataclysmic variable 1RXS J094432.1+035738
• Dwarf Novae with Newly Determined Parallaxes: Model Analyses of VY Aquari, RU Pegasi, and T Leonis
• The new cataclysmic variable RX J1554.2+2721 in the period gap

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• SDSS unveils a population of intrinsically faint cataclysmic variables at the minimum orbital period
• Survey of Period Variations of Superhumps in SU UMa-Type Dwarf Novae
• On the evolutionary status of short period cataclysmic variables
• Effective Temperatures of Cataclysmic Variable White Dwarfs as a Probe of their Evolution
• New Method to Estimate Binary Mass Ratios by Using Superhumps
• Evidence for reduced magnetic braking in polars from binary population models
• Cataclysmic Variables from SDSS VII. The Seventh Year (2006)
• The space density and X-ray luminosity function of non-magnetic cataclysmic variables
• The space density of cataclysmic variables: constraints from the ROSAT North Ecliptic Pole Survey
• Orbital periods of cataclysmic variables identified by the SDSS. III. Time-series photometry obtained during the 2004/5 International Time Project on La Palma
• Survey of Period Variations of Superhumps in SU UMa-Type Dwarf Novae. VI: The Sixth Year (2013-2014)
• Data Mining for Dwarf Novae in SDSS, GALEX and Astrometric Catalogues
• Newly Discovered Cataclysmic Variables from the INT/WFC Photometric H alpha Survey of the Northern Galactic Plane
• Towards a volumetric census of close white dwarf binaries I.Reference samples
• Orbital periods of cataclysmic variables identified by the SDSS. II. Measurements for six objects, including two eclipsing systems
• Orbital periods of cataclysmic variables identified by the SDSS. V. VLT, NTT and Magellan observations of nine equatorial systems
• An evolved donor star in the long-period cataclysmic variable HS 0218+3229
• Spectroscopic Orbital Periods for 29 Cataclysmic Variables from the Sloan Digital Sky Survey
• Follow-up Studies of Five Cataclysmic Variable Candidates Discovered by LAMOST
• The Relationship Between X-ray Luminosity and Duty Cycle for Dwarf Novae and their Specific Frequency in the Inner Galaxy
• An Halpha-selected sample of cataclysmic variables -- I. Observations of newly discovered systems
• An Halpha-selected sample of cataclysmic variables -- II. Implications for CV evolution
• Characterization of Dwarf Novae Using SDSS Colors
• Astrophysics in 2006
• Spectroscopic Studies of 30 Short-period Cataclysmic Variable Stars, and Remarks on the Evolution and Population of Similar Objects
• The Incidence of Dwarf Novae in Large Area Transient Searches
• The orbital and superhump periods of the dwarf nova HS 0417+7445 in Camelopardalis
• Transient behavior of three SU UMa-type dwarf novae; AR Pic, QW Ser and V521 Peg