Section: PZ: main journal
RS CVn Stars Among Variables with Possible CW Classification in the ASAS-3 Survey
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.
Photometric Investigation of Bright Type II-P Supernova 2004dj
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.
The Infrared Variations of Cyg X-1 (V1357 Cyg), 1995 - 2007
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.
SN 2005kd: Another Very Luminous, Slowly Declining Type IIn Supernova
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.
Long-Term Photometric and Spectral Variations of DI Cephei
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.
Photometric Observations of Two Type II-P Supernovae: Normal SN II-P 2004A and Unusual SN 2004ek
CCD BVRI photometry is presented for type II Supernovae 2004A and 2004ek. SN 2004A is found to be a typical SN II-P, with the shape of the light and color curves and maximum luminosity closely matching those for SN 1999em. SN 2004ek shows unusual light curves with long flat plateau in the B band, two peaks in the V band and prominent brightening in the R and I bands, starting about 45 days past outburst. The brightness decline after the plateau stage is probably quite slow. The plateau luminosity is about 1.5 mag higher than average for SNe II-P.
Multi-night CCD observations of the previously unknown variable GSC 02805–00766 reveal its nature as a contact binary. We present its light elements and light curve.
The Recent Period Evolution of the RRc stars HY Com, RU Psc and AP Ser
The first overtone RR Lyrae stars HY Com, RU Psc and AP Ser have shown frequent sudden period changes in recent years, as calculated from NSVS and ASAS-3 data.
We present the discovery, photographic and V-band CCD observation of a new High Amplitude Delta Scuti star USNO-A2.0 0975-09853705.