Based on O-C curves, we present detailed period investigations of two weak-contact binaries CC Com and BV Dra. It is found that the periods of these two binaries have varied in a cyclic variation way superposed on a secular period change. The periods and amplitudes of the cyclic variations are P_3_=23.6(+/-0.4)yr and A=0.0028(+/-0.0003)d for CC Com and P_3_=23.8(+/-0.6)yr and A=0.0029(+/-0.0003)d for BV Dra.
We present a 1.42deg^2^ mosaic of diffuse X-ray emission in the Great Nebula in Carina from the Chandra X-ray Observatory Advanced CCD Imaging Spectrometer camera. After removing >14000 X-ray point sources from the field, we smooth the remaining unresolved emission, tessellate it into segments of similar apparent surface brightness, and perform X-ray spectral fitting on those tessellates to infer the intrinsic properties of the X-ray-emitting plasma. By modeling faint resolved point sources, we estimate the contribution to the extended X-ray emission from unresolved point sources and show that the vast majority of Carina's unresolved X-ray emission is truly diffuse. Line-like correlated residuals in the X-ray spectral fits suggest that substantial X-ray emission is generated by charge exchange at the interfaces between Carina's hot, rarefied plasma and its many cold neutral pillars, ridges, and clumps.
This catalog contains the fourteenth, fifteenth, and sixteenth sections of the 5C Cambridge survey of radio sources. This catalog reports further 408 and 1407 MHz observations of the 5C12 area (Benn et al. 1982), which were carried out with the One-Mile Telescope at Cambridge to provide more accurate positions for the 5C12 sources and to extend the 5C12 catalog. Positions and flux densities were measured for 691 sources in a 5 degree x 5 degree area near the north galactic pole. The catalog data include the serial (source) number, right ascension (B1950.0) and declination (B1950.0), rms uncertainty in 408 MHz position, peak 408 MHz flux density and rms uncertainty, effective envelope attenuation (P_eff) at 408 MHz, difference between the 408 MHz and 1407 MHz positions, rms uncertainty in 1407 MHz position, peak 1407 MHz flux density and uncertainty, envelope attenuation P at 1407 MHz and radio spectral index between 408 MHz and 1407 MHz.
We measured the angular separations, position angles, Delta(V), Delta(y) and Delta(I) of wide visual double stars during the period 2003-2005. At least one component of the double stars in our sample has an entry in the Hipparcos catalogue.
Observations of the globular cluster M10 were taken at the Kitt Peak National Observatory (KPNO) 0.9 m telescope on the nights of UT dates 1995 May 6 and 9 using BVI filters. All frames were taken using a 2048x2048 pixel CCD with pixels covering 0.68 arcseconds on a side, for a total field of approximately 23.2 arcminutes on a side. The data were calibrated against Stetson (2000PASP..112..925S) standard stars. Additional high-resolution images were taken at the 3.6 m Canada-France-Hawaii Telescope (CFHT) on the night of UT date 1993 April 13 in BI filters. These observations used a 1200x1200 pixel CCD with pixels covering 0.11 arcseconds on a side, for a total field 2.2 arcminutes on a side, roughly centered on the cluster core. These data were calibrated against the KPNO data.
We present for the globular cluster NGC 5927 the first multicolor CCD photometry that reaches below the cluster's main sequence turnoff. The turnoff is located approximately at V_TO_=20.1mag, (B-V)_TO_=1.18mag, (V-I)_TO_=1.30mag. There is a hint of horizontal branch morphology variations with distance from the cluster center. Using the isochrones of VandenBerg & Bell (1985ApJS...58..561V), we derive the cluster age to be about 15Gyr.
The observations were done on the nights of UT dates 1995 May 6 and 9 by using the Kitt Peak National Observatory (KPNO) 0.9 m telescope. The file contains BVI data of the globular cluster M12. All frames were taken using a 2048x2048 pixel CCD with pixels covering 0.68 arcseconds on a side, for a total field of approximately 23.2 arcminutes on a side. The data were calibrated against Stetson (2000PASP..112..925S) standard stars.
We present CCD BVI observations obtained for 1759 stars in 4'x4' regions around the unstudied southern stellar aggregates Ruprecht 103, 124, 129, 146 and 166, which are described as open clusters in several catalogues. Our analysis shows that none of these stellar groups are genuine open clusters since no clear main sequences or other meaningful features can be seen in their colour-magnitude diagrams. Star counts carried out within and outside the cluster candidate fields not only support these results but also show that the studied objects do not appear to be candidate late stages of star cluster dynamical evolution.
We present BVI photometry for poorly known southern hemisphere open clusters: NGC 2425, Haffner 10 and Czernik 29. We have calculated the density profile and established the number of stars in each cluster. The colour-magnitude diagrams of the objects show a well-defined main sequence. However, the red giant clump is present only in NGC 2425 and Haffner 10. For these two clusters we estimated the age as 2.5+/-0.5Gyr assuming metallicity of Z=0.008. The apparent distance moduli are in the ranges 13.2<(m-M)_V<13.6 and 14.3<(m-M)_V<14.7, while heliocentric distances are estimated to be 2.9<d<3.8kpc and 3.1<d<4.3kpc, respectively for NGC 2425 and Haffner 10. The angular separation of 2.4deg (150pc at mean distance) may indicate a common origin of the two clusters.
