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تسجيل مستخدم جديدTime-resolved photometry of cataclysmic variables
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We present time-resolved photometry of two cataclysmic variables whose CCD photometric observations were obtained with the 1m telescope at the South African Astronomical Observatory in October 2002 and August 2003 and with the 1m telescope at Hoher List in Germany. Concerning MCT 2347-3144 we detect for the first time a period of 6.65h. For V1193 Ori the 3.96 h periodicity has for the first time been confirmed through time-resolved photometry.
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Time-resolved HST UV eclipse spectrophotometry is presented for the magnetic CVs V1309 Ori, MN Hya, V2301 Oph, and V1432 Aql. Separation of the light curves into wavebands allows the multiple emission components to be distinguished. Photospheric hot
spots are detected in V1309 Ori and V2301 Oph. The emission- line spectra of V1309 Ori and MN Hya are unusual, with the strength of N V 1240 and N IV 1718 suggesting an overabundance of nitrogen. Three epochs of observation of the asynchronous V1432 Aql cover ~1/3 of a 50-day lap cycle between the white dwarf spin and binary orbit. The light curves vary from epoch to epoch and as a function of waveband. The dereddened UV spectrum is extremely bright and the spectral energy distribution coupled with the duration of eclipse ingress indicate that the dominant source of energy is a hot (T~35,000K) white dwarf. Undiminished line emission through eclipse indicates that the eclipse is caused by the accretion stream, not the secondary star. The hot white dwarf, combined with its current asynchronous nature and rapid timescale for relocking, suggests that V1432 Aql underwent a nova eruption in the past 75-150 yr. The reversed sense of asynchronism, with the primary star currently spinning up toward synchronism, is not necessarily at odds with this scenario, if the rotation of the magnetic white dwarf can couple to the ejecta during the wind phase of the eruption.
We present time-series photometry of nine cataclysmic variables: EI UMa, V844Her, V751 Cyg, V516 Cyg, GZ Cnc, TY Psc, V1315 Aql, ASAS J002511+1217.12, V1315 Aql and LN UMa. The observations were conducted at various observatories, covering 170 hours
and comprising 7,850 data points in total. For the majority of targets we confirm previously reported periodicities and for some of them we give, for the first time, their spectroscopic orbital periods. For those dwarf-nova systems which we observed during both quiescence and outburst, the increase in brightness was followed by a decrease in the amount of flickering. Quasi-periodic oscillations have either been discovered, or were confirmed. For the eclipsing system V1315 Aql we have covered 9 eclipses, and obtained a refined orbital ephemeris. We find that, during its long baseline of observations, no change in the orbital period of this system has occurred. V1315 Aql also shows eclipses of variable depth.
We present high-speed, three-colour photometry of the faint eclipsing cataclysmic variables XZ Eri and DV UMa. We determine the system parameters through two techniques: first, timings of the eclipse contact phases of the white dwarf and bright-spot
using the derivative of the light curve; and secondly, a parameterized model of the eclipse fitted to the observed light curve by chi-squared minimisation. For both objects, we prefer the latter method, as it is less affected by photon noise and rapid flickering. For XZ Eri we obtain a mass ratio q = 0.1098 +/- 0.0017 and an orbital inclination i = 80.16 +/- 0.09 degrees. For DV UMa we derive figures of q = 0.1506 +/- 0.0009 and i = 84.24 +/- 0.07 degrees. The secondary star in XZ Eri has a very low mass Mr/Msun = 0.0842 +/- 0.0024, placing it close to the upper limit on the mass of a brown dwarf.
We present high-speed photometric observations of 25 cataclysmic variables detected by the All Sky Automated Search for Super-Novae (ASAS-SN), the Mobile Astronomical System of the TElescope-Robot (MASTER) and the Catalina Real-Time Transient Survey
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We present 855 cataclysmic variable candidates detected by the Catalina Real-time Transient Survey (CRTS) of which at least 137 have been spectroscopically confirmed and 705 are new discoveries. The sources were identified from the analysis of five y
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