Publications
Section: PZ: main journal
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CCD UBVRI photometry covering about 320 days is presented for the type IIb SN 2008ax. Its photometric behavior is typical of core-collapse SNe with low amount of hydrogen. The main photometric parameters are derived and a comparison with SNe of similar types is reported. Preliminary modeling is carried out, and the results are compared to the observed light curves. The main parameters of the hydrodynamical models are close to those used for SN IIb 1993J.
New UBV photometry obtained in 2000 - 2008 is presented for the
post-AGB star IRAS 22272+5435 = V354 Lac. The star showed
semi-regular light variations with varying amplitudes. The maximal
amplitude did not exceed: Delta V = 0.5, Delta B = 0.7,
and Delta U = 1.0. For 2000 - 2008, we have found a
photometric period near 128 days. The analysis of long-term
observations in 1990 - 2008 reveals variations with two close
periods: 128 and 131 days, causing amplitude modulation. The
V -(B-V) diagram shows a clear correlation: the star is
generally bluer when brighter. From our UBV data, we derive
E(B-V)=0.5 and conclude that the spectral type of the star
varies between K1 and K7 during pulsations. The mean UBV data for
V354 Lac have not changed during the past 19 years:
Recent multicolor photometry of N. Kurochkin's nova or novalike variable star LW Cas has been obtained using the SAO 1-m Zeiss reflector. The amplitude of the outburst in 1952 was 5 mag in the B band. In 2008, LW Cas consists of a central stellar object of 20 mag B surrounded by a halo of the same brightness and a 7" comet-like tail directed to the east. The star is associated with a young star-forming region and seen through a dark cloudy nebulosity. There is evidence of bright light echo seen two years after the outburst.
We present our discovery of a new double-mode RR Lyrae variable, USNO-A2.0 1650-01540181. The study is based on our original CCD observations, carried out at the Astrotel-Caucasus Observatory.
We present a list of 109 probable RS CVn variables among stars in the ASAS-3 catalog with Population II Cepheid classification as the main one or an alternative one. These stars are identified with X-ray sources and have light curves (from ASAS-3 data) in no contradiction with the suggested RS CVn classification.
CCD UBVRI photometry is presented for type II SN 2004dj for about 1200 days, starting on day 2 past discovery. The photometric behaviour is typical of SNe II-P, although some minor peculiarities are noticed. We compare the photometric data for the host cluster S96 before and after the SN 2004dj outburst and do not find any significant changes.
We present the results of our long-term (about 13 years) J and K photometry of the X-ray binary Cyg X-1. The object's JK variability amplitudes were less than 0.2 mag. The J and K orbital light curves are appreciably asymmetric in quadratures. The secondary minimum is deeper, in comparison to the primary, and it is probable that the star becomes hotter at secondary minima. The ratio of average radii of the supergiant in quadratures and in minima is about 1.02 if the temperature of the optical component does not change during its orbital motion. We estimate the interstellar extinction as E(B-V) = 1.025+/-0.006 and the distance to the star, as d = (2.44+/-0.04) kpc. The luminosity and radius of the optical component are respectively ~2.8 x 10^5 L(Sun) and 21 R(Sun). The JK variations of the X-ray binary Cyg X-1 in 1995 - 2007 can be explained with orbital ellipsoidal variations of the optical component (hot supergiant HD 226868), accompanied with long-term JK variations on a time scale of 11.5 years with an amplitude of 0.06-0.07 mag. In 1995 - 2007, the JK brightness fluctuations probably had a 294-day periodicity with an amplitude of no more than 0.03 - 0.05 mag.
CCD UBVRI photometry is presented for type IIn SN 2005kd. The maximum luminosity exceeded Mv=-19.8, and the SN remained brighter than -18m for about 400 days. While its overall photometric evolution is quite similar to SN 1997cy, SN 2005kd shows a plateau at phases between 119 and 311 days past explosion, which is a unique feature for SNe IIn.
We have analyzed the photometric and spectral variations of the classical T Tauri star DI Cep for the last 50 years. Currently the star is at its faintest state and possesses an emission spectrum in the visual range. Synchronous spectroscopy and UBVR photometry show that the higher the brightness, the stronger were the intensities of hydrogen Halpha, Hbeta emission lines and of FeII, HeI 5876 A emissions. For the first time, we detected, with a high probability, quasi-periodic variations of the star's brightness and of its spectrum with the period P = 2020 +/- 200 days.
I present the discovery of a pulsating component in light variations of the known eclipsing binary NSV 10993 based on the NSVS and ASAS-3 publicly available data. |
