Photometric and Spectroscopic Investigation of the Dwarf Nova HS 0218+3229: A Short Review

This paper is devoted to the study of the cataclysmic variable HS 0218+3229 using the photometric and spectroscopic observations

Multipassband photometric mapping of three fast rotating stars: HII 1883, AP 86 and AP 226

© 2014 COSPAR. The analysis of multipassband photometry was carried out for three rapidly rotating stars: HII 1883, AP 86 and AP 226. Two different approaches were used for starspot mapping. In the first approach the stellar spottedness is approximated by set of circular spots. Spot parameters (coordinates of the spot center, radius and temperature) are searched by fitting of observed light curves. The idea of the second approach is consisted in partition of the stellar surface into small areas. Searching of the temperature distribution is carried out by the fitting of the observed light curves. Stellar atmosphere theory was used for modeling of the theoretical light curves in both techniques

Optical observations of "hot" novae returning to quiescence

We have monitored the return to quiescence of novae previously observed in outburst as supersoft X-ray sources, with optical photometry of the intermediate polar (IP) V4743 Sgr and candidate IP V2491 Cyg, and optical spectroscopy of these two and seven other systems. Our sample includes classical and recurrent novae, short period (few hours), intermediate period (1-2 days) and long period (symbiotic) binaries. The light curves of V4743 Sgr and V2491 Cyg present clear periodic modulations. For V4743 Sgr, the modulation occurs with the beat of the rotational and orbital periods. If the period measured for V2491 Cyg is also the beat of these two periods, the orbital one should be almost 17 hours. The recurrent nova T Pyx already shows fragmentation of the nebular shell less than 3 years after the outburst. While this nova still had strong [OIII] at this post-outburst epoch, these lines had already faded after 3 to 7 years in all the others. We did not find any difference in the ratio of equivalent widths of high ionization/excitation lines to that of the Hbeta line in novae with short and long orbital period, indicating that irradiation does not trigger high mass transfer rate from secondaries with small orbital separation. An important difference between the spectra of RS Oph and V3890 Sgr and those of many symbiotic persistent supersoft sources is the absence of forbidden coronal lines. With the X-rays turn-off, we interpret this as an indication that mass transfer in symbiotics recurrent novae is intermittent.Comment: In press in Monthly Notices of the Royal Astronomical Societ

Spectral and photometric studies of the polar USNO-A2.0 0825-18396733

© 2015, Pleiades Publishing, Ltd. Results of photometric and spectral studies of the new magnetic cataclysmic variable (polar) USNO-A2.0 0825-18396733 are presented. Photometric data in the B, V, and Rc filters show that this object exhibits a red excess of Rc − V = 1m. A red continuum with superposed strong single-peaked Balmer emission lines and HeII λ4686 Å emission, weak lines of neutral helium, and lines of heavy elements are observed in the object’s spectra. Doppler maps constructed using the hydrogen and ionized-helium lines indicate that these lines form near the inner Lagrangian point, and that their formation is associated with an accretion stream. The spectra and radial-velocity curves indicate the eclipse of the white dwarf in the system to be partial. Radial-velocity curves derived for emission lines are used to estimate the component masses. The mass of the white dwarf is estimated to be 0.71–0.78M⊙, and the mass of the red dwarf to be 0.18–0.20M⊙

Spectroscopic study of the polar BS Tri

© 2015, Pleiades Publishing, Inc. We have analyzed the spectra of the cataclysmic variable BS Tri taken in September 2011 and August 2012 with the 6-m BTA SAO RAS telescope. The object’s spectra exhibit a flat continuum with superimposed strong hydrogen Balmer, neutral and ionized helium emission lines. Our analysis of the line profiles has shown that they consist of several components that are formed in the accretion structure and on the irradiated red dwarf surface. The measured radial velocities of one of the components of the line forming in a spot on the red dwarf surface have allowed the parameters of the system to be estimated: M1 = 0.75 ± 0.02 M⊙, M2 = 0.16 ± 0.01 M⊙, q = 0.21 ± 0.02, and RL2 = 0.18 ± 0.02 R⊙. The Doppler maps constructed from the emission lines show no disk accretion, defining the system as a polar

PN G068.1+11.0: A young pre-cataclysmic variable with an extremely hot primary

© 2016, Pleiades Publishing, Ltd.An analysis of spectroscopic and photometric data for the young pre-cataclysmic variable (PCV) PN G068.1+11.0, which passed through its common-envelope stage relatively recently, is presented. The spectroscopic and photometric data were obtained with the 6-m telescope and Zeiss-1000 telescope of the Special Astrophysical Observatory. The light curves show sinusoidal brightness variations with the orbital-period time scale and brightness-variation amplitudes of Δm = 1.m41, 1.m62, and 1.m57 in the B, V, and R bands, respectively. The system’s spectrum exhibits weak HI (Hβ–Hδ) andHeII λλ4541, 4686, 5411 Å absorption lines during the phases of minimum brightness, as well as HI, HeII, CIII, CIV, NIII, and OII emission lines whose intensity variations are synchronized with variations of the integrated brightness of the system. The emission-line formation in the spectra can be fully explained by the effects of fluorescence of the ultraviolet light from the primary at the surface of the cool star. All the characteristics of the optical light of PN G068.1+11.0 confirm that it is a young PCV containing sdO subdwarf. The radial velocities were measured from a blend of lines of moderately light elements, CIII+NIII λ4640 Å, which is formed at the surface of the secondary due to reflection effects. The ephemeris of the system has been improved through a joint analysis of the radial-velocity curves and light curves of pre-cataclysmic variable, using modelling of the reflection effects. The fundamental parameters of PN G068.1+11.0 have been determined using two evolutionary tracks for planetary-nebula nuclei of different masses (0.7 M⊙and 0.78M⊙). The model spectra for the system and a comparison with the observations demonstrate the possibility of refining the components’ effective temperatures if the quality of the spectra used is improved

Spectral and photometric studies of polar CRTS CSS 130604 J 215427+155714

© 2017, Pleiades Publishing, Ltd.We present the results of spectroscopic and photometric studies of a new polar CRTS CSS130604 J 215427+155714, conducted at the telescopes of the SAO RAS. Analysis of the photometric series of observations allowed to clarify the orbital period of the system, Po = 0.d 0672879 (±0.0000003). We build radial velocity curves and trace the intensity variations in the Hβ and Hγ hydrogen lines and He II λ 4686 ˚A ionized heliumline. Based on the Hβ and He II lines we build Doppler maps. It is shown that the line formation region is localized near the Lagrange point. The following parameter estimates of the system are obtained:M1 = 0.83 ± 0.10M⊙, M2 = 0.15 ± 0.01M⊙, q = M2/M1 = 0.18 ± 0.03, i = 53◦ ± 5◦. Based on the results of spectral, photometric and previously published polarimetric observations the possible geometric model of the system is discussed

Photometric and spectral studies of the eclipsing polar CRTS CSS081231 J071126+440405

© 2016, Pleiades Publishing, Ltd.We present the results of the study of the eclipsing polar CRTS CSS081231 J071126+440405. Photometric observations allowed us to refine the orbital period of the system (Formula presented.). Considerable changes in the appearance of the object’s spectra have occurred over the period of September 20–21, 2001: the slope of the continuum changed from “red” to “blue”, and the variability of the line profiles over the duration of the orbital period has also changed. Doppler maps have shown a shift of the emission line-forming region along the accretion stream closer to the white dwarf. We measured the duration of the eclipse of the system and imposed constraints on the inclination angle (Formula presented.). The derived radial velocity amplitude was used to obtain the basic parameters of the system: M1 = 0.86 ± 0.08M⊙, M2 = 0.18 ± 0.02 M⊙, q = 0.21 ± 0.01, RL2 = 0.20 ± 0.03 R⊙, A = 0.80 ± 0.03 R⊙. The spectra of the object exhibit cyclotron harmonics. Their comparison with model spectra allowed us to determine the parameters of the accretion column: B = 31–34 MG, Te = 10–12 keV, θ = 80–90°, and Λ = 105

Superoutburst of a New Sub-Period-Minimum Dwarf Nova CSS130418 in Hercules

Multicolour photometry of a new dwarf nova CSS130418 in Hercules, which underwent superoutburst on April 18, 2013, allow to classified it as a WZ Sge-type dwarf nova. The phase light curves for different stages of superoutburst are presented. The early superhumps were used to determine the orbital period Porb = 64.84(1) minutes, which is shorter than the period minimum ~78 minutes for normal hydrogen-rich cataclysmic variables. We found the mean period of ordinary superhumps Psh = 65.559(1) minutes. The quiescent spectrum is rich in helium, showing double peaked emissionlines of H I and He I from accretion disk, so the dwarf nova is in a late stage of stellar evolution