3 research outputs found
The Wendelstein Calar Alto Pixellensing Project (WeCAPP): the M31 Nova catalogue
We present light curves from the novae detected in the long-term, M31
monitoring WeCAPP project. The goal of WeCAPP is to constrain the compact dark
matter fraction of the M31 halo with microlensing observations. As a by product
we have detected 91 novae benefiting from the high cadence and highly sensitive
difference imaging technique required for pixellensing. We thus can now present
the largest CCD and optical filters based nova light curve sample up-to-date
towards M31. We also obtained thorough coverage of the light curve before and
after the eruption thanks to the long-term monitoring. We apply the nova
taxonomy proposed by Strope et al. (2010) to our nova candidates and found 29
S-class novae, 10 C-class novae, 2 O-class novae and 1 J-class nova. We have
investigated the universal decline law advocated by Hachichu and Kato (2006) on
the S-class novae. In addition, we correlated our catalogue with the literature
and found 4 potential recurrent novae. Part of our catalogue has been used to
search for optical counter-parts of the super soft X-ray sources detected in
M31 (Pietsch et al. 2005). Optical surveys like WeCAPP, and coordinated with
multi-wavelength observation, will continue to shed light on the underlying
physical mechanism of novae in the future.Comment: 15 pages, 15 figures, 7 tables, A&A accepted for publication. The
appendix is stored in the Data Conservanc
Dwarf novae in the Hamburg quasar survey : rarer than expected
Aims. We report the discovery of five new dwarf novae that were spectroscopically identified in the Hamburg Quasar Survey (HQS),and discuss the properties of the sample of new dwarf novae from the HQS.
Methods. Follow-up time-resolved spectroscopy and photometry have been obtained to characterise the new systems.
Results. The orbital periods determined from analyses of the radial velocity variations and/or orbital photometric variability are Porb 105.1min or Porb 109.9min for HS 0417+7445, Porb = 114.3 ± 2.7min for HS 1016+3412, Porb = 92.66 ± 0.17 min for HS 1340+1524, Porb = 272.317 ± 0.001 min for HS 1857+7127, and Porb = 258.02 ± 0.56 min for HS 2214+2845. HS 1857+7127 is found to be partially eclipsing. In HS 2214+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 HS 0417+7445, identifying the system as a SUUMatype
dwarf nova. HS 1016+3412 and HS 1340+1524 have rare outbursts, and their subtype is yet undetermined. HS 1857+7127 frequently varies in brightness and may be a ZCam-type dwarf nova. HS 2214+2845 is a UGem-type dwarf nova with a most likely cycle length of 71 d.
Conclusions. To date, 14 new dwarf novae have been identified in the HQS. The ratio of short-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, newly identified and previously known, suggest that most, or possibly all 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. This suggests that those post-bounce systems have markedly weaker HÎČ emission lines compared to the average known short-period CVs, and undergo no or extremely rare outbursts