Our time series analysis of V368 Cep photometry ascertains the rotation period of 2.74d uniquely. The manifestations of starspot induced luminosity variations in this chromospherically active star include rapid light curve changes and differential rotation of about 3%. We conclude that the single rapidly rotating variable V368 Cep is a high inclination K1V post T Tauri star.
We performed a deep wide-field (6.76 square-degrees) near-infrared survey with the VISTA telescope that covers the entire extent of the Carina nebula complex. Complementing the VISTA near-infrared catalog with Spitzer IRAC mid-infrared photometry improves the situation of the background contamination considerably. We find that a (J-H) versus (Ks-[4.5]) color-color diagram is well suited to tracing the population of YSO-candidates (cYSOs) by their infrared excess. We identify 8781 sources with strong infrared excess, which we consider as cYSOs. This sample is used to investigate the spatial distribution of the cYSOs with a nearest-neighbor analysis. The surface density distribution of cYSOs agrees well with the shape of the clouds as seen in our Herschel far-infrared survey. The strong decline in the surface density of excess sources outside the area of the clouds supports the hypothesis that our excess-selected sample consists predominantly of cYSOs with a low level of background contamination.
We present new results from optical photometric and spectroscopic observations of the eruptive pre-main sequence star V2493 Cyg (HBC 722). The object has continued to undergo significant brightness variations over the past few months and is an ideal target for follow-up observations.
We present the results of our UBV and JHKLM photometry for the semiregular pulsating variable V1027 Cyg, a supergiant with an infrared excess, over the period from 1997 to 2015 (UBV) and in 2009-2015 (JHKLM). Together with the new data, we analyze the photometric observations of V1027 Cyg that we have obtained and published previously. Our search for a periodicity in the UBV brightness variations has led to several periods from P=212d to 320d in different time intervals. We have found the period P=237d based on our infrared photometry. The variability amplitude, the lightcurve shape, and the magnitude of V1027 Cyg at maximum light change noticeably from cycle to cycle.
We present multicolor photometry of the massive interacting close binary system V729 Cyg. The light variations of V729 Cyg were observed in the Bessel U, B, V, R and I bands over 65 nights between August 2010 and October 2011.
Six years of new photometry of V 1794 Cyg is combined with the previously published data. These data are processed into two decades of homogeneous standard Johnson UBVRI photometry, which contains 1207, 1837, 1927, 867 and 75 observations in U, B, V, R and I, respectively.
We present the photometric analysis of the detached eclipsing binary V2480 Cyg. After taking the photometric data, the light curve was analyzed in PHOEBE software, which uses the Wilson-Devinney code. Due to the observed O'Connell (1951PRCO....2...85O) effect in light curve, we introduce a spotted model with 3 spots on the components, and the exact parameters of the system have been achieved. The main parameters of the system were calculated as about q_ptm_=1.7, T_eff1_=8075K and T_eff2_=3829K.
This table presents optical UBVRI broadband photo-polarimetry of the EXPORT sample obtained at the 2.5m Nordic Optical Telescope. The database consists of multi-epoch photo-polarimetry of 68 pre-main-sequence and main-sequence stars.
We present the results of a large spectroscopic survey of the LMC, consisting of more than 1300 radial velocities measured accurately with the 2dF instrument during three observing compaigns 1999-2002. In this sample, no evidence is found for any extraneous, kinematically distinct population over the expected LMC and Galactic components. We discuss the significance of this finding for the LMC self-lensing models. The sample was randomly selected from three APM photographic plates with 16<=R<=18mag and -1.0<=Bj-R<=2.5mag. The fields were centered on previous microlensing events. The 1200V grating was used with 1.1{AA} per pixel resolution over 4625-5765{AA}. The zero point of the velocity of LMC K-type stars is set by cross-correlating with a K-type standard star. For sample stars of other spectral type we assume no systematic change of the peak of velocity distribution with spectral type.
We report on a new, wide-field (20x20arcmin^2^), multicolour (UBVI), photometric campaign in the area of the nearby old open cluster NGC 2112. At the same time, we provide medium-resolution spectroscopy of 35 (and high-resolution of additional 5) red giant and turn-off stars. This material is analysed with the aim to update the fundamental parameters of this traditionally difficult cluster, which is very sparse and suffers from heavy field star contamination. Among the 40 stars with spectra, we identified 21 bona fide radial velocity members which allow us to put more solid constraints on the cluster's metal abundance, long suggested to be as low as the metallicity of globulars. As indicated earlier by us on a purely photometric basis, the cluster [Fe/H] abundance is slightly supersolar ([Fe/H]=0.16+/-0.03) and close to the Hyades value, as inferred from a detailed abundance analysis of three of the five stars with higher resolution spectra. Abundance ratios are also marginally supersolar. Based on this result, we revise the properties of NGC 2112 using stellar models from the Padova and Yale-Yonsei groups.
