O. I. Spiridonova

Steps toward Determination of the Size and Structure of the Broad-Line Region in Active Galactic Nuclei. XVI. A 13 Year Study of Spectral Variability in NGC 5548

We present the final installment of an intensive 13 year study of variations of the optical continuum and broad Hemission line in the Seyfert 1 galaxy NGC 5548. The database consists of 1530 optical continuum measurements and 1248 Hmeasurements. The Hvariations follow the continuum variations closely, with a typical time delay of about 20 days. However, a year-by-year analysis shows that the magnitude of emission-line time delay is correlated with the mean continuum flux. We argue that the data are consistent with the simple model prediction between the size of the broad-line region and the ionizing luminosity, r / L 1=2 ion . Moreover, the apparently linear nature of the correlation between the Hresponse time and the nonstellar optical continuum Fopt arises as a consequence of the changing shape of the continuum as it varies, specifically Fopt / F 0:56 UV . Subject headings: galaxies: active — galaxies: individual (NGC 5548) — galaxies: nuclei — galaxies: Seyfert

Analysis of fundamental parameters for V477 Lyr

We analyze the photometric and spectroscopic observations of the young pre-cataclysmic variable (pre-CV) V477 Lyr. The masses of both binary components have been corrected by analyzing their radial velocity curves. We show that agreement between the theoretical and observed light curves of the object is possible for several sets of its physical parameters corresponding to the chosen temperature of the primary component. The final parameters of V477 Lyr have been established by comparing observational data with evolutionary tracks for planetary nebula nuclei. The derived effective temperature of the O subdwarf is higher than that estimated by analyzing the object’s ultraviolet spectra by more than 10000 K. This is in agreement with the analogous results obtained previously for the young pre-CVs V664 Cas and UU Sge. The secondary component of V477 Lyr has been proven to have a more than 25-fold luminosity excess compared to main-sequence stars of similar mass. Comparison of the physical parameters for the cool stars in young pre-CVs indicates that their luminosities do not correlate with the masses of the objects. The observed luminosity excesses in such stars show a close correlation with the post-common-envelope lifetime of the systems and should be investigated within the framework of the theory of their relaxation to the state of main-sequence stars.

Nuclear activity of NGC 4151 as inferred from UBVRI observations in 1989–2000

We present our broadband UBVRI observations of the nucleus of the Seyfert galaxy NGC 4151 from 1989 until 2000 at three astronomical observatories: the Crimean Station of the Sternberg Astronomical Institute, the Special Astrophysical Observatory in the Caucasus, and the Maidanak Observatory of the Ulugbek Astronomical Institute in Uzbekistan. All data have been reduced to a single system and are given for an A=27.″5 aperture. Regular R and I observations show that the pattern of optical variability is the same in all bands; the relative variability amplitude decreases from U to V, but it is even slightly larger in R than in V. The variability amplitude of the component fluctuating on time scales of several months is proportional to the UBV flux from the component varying on times scales of several years. The correlation between the slow and rapid components significantly weakens in the red, and no correlation has been found between the flux from the slow component and the amplitude of the rapid component in R. The color characteristics correspond to the recombination radiation from an optically thick plasma beyond the Balmer limit.

Photometry of the poorly studied galactic open star clusters King 13, King 18, King 19, King 20, NGC 136, and NGC 7245

We present the results of our BV RcIc CCD photometry for six Galactic open star clusters toward the Perseus spiral armperformed at the Special Astrophysical Observatory of the Russian Academy of Sciences. Based on these data and using JHKs photometry from the 2MASS catalog, we have determined the ages, distances, and color excesses for the clusters: 710 Myr, 2960−340+400 pc, 0·m56 ± 0·m04 (King 13); 130 Myr, 3010−280+300 pc, 0·m69 ± 0·m04 (King 18); 560 Myr, 2630−270+310 pc, 0·m69 ± 0·m08 (King 19); 160 Myr, 1750−70+80 pc, 0·m77 ± 0·m05 (King 20); 250 Myr, 5220−320+350 pc, 0·m70 ± 0·m09 (NGC 136); 320 Myr, 3390−200+210 pc, 0·m43 ± 0·m03 (NGC 7245).

Nuclear activity of NGC 5548 from UBVRI observations during 1990–2000

AbstractWe present our UBV RI observations of the nucleus of the Seyfert Galaxy NGC 5548 from 1990 until 2000 at four astronomical observatories: the Crimean Station of the Sternberg Astronomical Institute, the Special Astrophysical Observatory of the Russian Academy of Sciences, the Crimean Astrophysical Observatory (Ukraine), and the Mount Maidanak Observatory of the Ulugbek Astronomical Institute (Uzbekistan). All data have been reduced to a single system and are given for an A=14.3″ aperture. Large light variations have been observed in the galactic nucleus over the last ten years: the total variability amplitude through the A=14.3″ aperture was

Variability of the Hβ broad emission line in agn

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The Intermediate-Age Pre-Cataclysmic Variables SDSS J172406+562003 and RE J2013+ +4002

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