New and complete UBV light curves and times of minimum are presented for the Algol type eclipsing binary V477 Cygni (Sp. A3V+F5V, m_v_=8.5, P=2.347days). The binary orbit of the system is highly eccentric and the system shows an apsidal motion. Using the Wilson-Devinney method, two photometric models, without (MODEL A) and with (MODEL B) third-body light contribution to the total light of the system, are obtained. Period analysis also gives some slender evidence for the unseen third-body in the system with the orbital period of about 157 years. In the MODEL A approximation the apsidal motion period is obtained to be 371 years while it is about 434 years in the MODEL B approximation. The photometric mass ratio (q=0.75) is in good agreement with the spectroscopic value given by Popper (1968ApJ...154..191P). The masses we obtained are 1.80+/-0.10 solar masses and 1.35+/-0.08 solar masses and the radii are 1.60+/-0.03 solar radii and 1.42+/-0.03 solar radii for the primary and secondary components, respectively. Absolute dimensions have been compared with the models using a moderate amount of convective overshooting and mass loss given by Claret & Gimenez (1991A&AS...87..507C). In the logM-logR diagram both components are located above but close to the ZAMS. It is possible to say from the logTe-logL diagram that the secondary component is just coming to the main sequence while the primary is slightly evolved from the ZAMS. The theoretical evolutionary models give an age of 6.4x10^8^yrs for the system.
New 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.
We present the results of the photometric CCD search for B-type pulsators in the central region of Chi Persei (NGC 884) open cluster. In addition to the two newly-discovered Beta Cephei stars we found 11 other variables in the observed field. The photometric data for them are given in the file 'bmag' and 'vmag' for B and V-filter data, respectively. In addition, we present the new UBV magnitudes for stars in the observed field. This is Table 4 of the paper, available only in electronic form.
The near-contact system RU UMi with an F0 primary and a K5 secondary was observed in U, B and V wavelengths in May and July 1998, as well as in March, May and July 1999. Six new observed times of minima are given and a new ephemeris is proposed. The basic parameters of the system extracted by our observations were used for spot modelling of the light curves. A simple spot distribution was determined, based on a model with one relatively small cool spot on the surface of the secondary. Absolute elements were calculated and the evolutionary status was determined. Our data favor a semi-detached configuration, with the secondary filling its inner Roche lobe; the primary must also be near the limits of its lobe.
The BV photometric investigation of the Southern globular cluster NGC 1904 was carried out using the 1m telescope of Cerro Las Campanas (CARSO, 2 nights in February 1973 and 2 nights in April 1973), and the 1m telescope at la Silla (ESO, 4 nights in February 1975). The identification of the stars was made by B. Skiff (Lowell Obs.) in October 2010.
We present new results of our UBV photometry for HD 179821=V1427 Aql, an F supergiant with an infrared excess, from 2000 to 2008. The semiregular low-amplitude ({Delta}=0.05-0.20mag) photometric variability of the star with a cycle period from 130 to 200 days is caused by pulsations, along with the instability of a variable stellar wind. V1427 Aql also exhibits a long-term trend in the brightness and colors that is probably attributable to a change in the stellar temperature as a result of mass loss episodes, which cause variations in the continuum formation level. We present the results of our JHKLM photometry for V1427 Aql in 1992-2008.
The photoelectric and photographic observations of the supergiant HD 179821 with a large infrared excess, a candidate for protoplanetary objects during 1899-1999 are presented.
We present UBV photoelectric observations of the W UMa star BF Pav obtained between 1987 and 1993. A time-of-minimum study allows detection of a likely period increase of about 0.015s/yr. The Wilson-Devinney code is employed to simultaneously model the B and V light curves for several fixed values of the mass ratio q. From the quality-of-fit of the different solutions an approximate value of q=1.4+/-0.2 is derived. Absolute values of masses, dimensions, and luminosities are estimated by means of standard mass-luminosity relations for main-sequence stars. The detected period variation determines a lower limit of 5x10^-7M_{sun}_/yr for the rate of mass transfer from the less-massive to the more-massive component. We speculate that BF Pav has recently become in contact and is now in a rapid phase of mass transfer.
We present our long-term photometric and spectroscopic observations of a high-latitude B supergiant with an infrared excess - the protoplanetary nebula IRAS 18062+2410. Our UBV observations in 2000-2006 have confirmed the rapid irregular photometric variability of the star with a maximum amplitude as high as 0.4m in V that we found previously. The B-V and U-B color indices vary with amplitudes as high as 0.10m and 0.25m, respectively, and show no clear correlation with the brightness. Our V-band CCD observations on 11 nights in 2006 have revealed brightness trends during the night. The variability of IRAS 18062+2410 is similar in pattern to the light variations in other hot post-AGB objects and some of the nuclei of young planetary nebulae. We assume that pulsations and a variable stellar wind can be responsible for the variability of these stars. In addition to the rapid variability, our 12-year-long observations have revealed a systematic decline in the mean brightness of IRAS 18062+2410.