New light and radial-velocity curves of V497 Cep, a binary in the open cluster NGC 7160, were obtained and the linear ephemeris of the system was refined to HJD(Min I)=(2446299.1596+/-0.0064)+(1.2028287d+/-0.0000015)dxE. The first light and radial-velocity curve solutions allowed us to derive the basic physical properties of this astrophysically important binary.
Photoelectric photometry is presented for a sample of 139 halo stars drawn an extension of the HK (Ca II H & K lines) objective-prism survey of Beers, Preston and Shectmann (1988ApJS...67..461) to the Northern Galactic hemisphere. The candidates for which photometry is reported here were selected to span a wide range of types, but are dominated by stars classified as type AB, A, or "metal-poor" (MP).
CCD photometry on the UBV and Washington systems, is presented for Be32, a so far unstudied rich open cluster located in the Galactic anticentre. Morphology of cluster and colour-magnitude diagram indicates that it is an old object with age close to ages of NGC 188 and NGC 2243 (about 6Gyr on the scale of VandenBerg isochrones). The cluster reddening is E(B-V)=0.16 and the estimated metallicity is [Fe/H]=-0.37+/-0.05. The apparent distance modulus is between 12.8 and 13.1.
We present UBV photometry of four fields within Shapley Constellation III and one field on the edge of the shell. Our fields cover roughly 20% of the region, mostly in the southern half. Determinations are made of ages of the fields, the star formation densities, and the initial mass function (IMF) slopes.
We examine the stellar population of an OB association, LH 47/48, which is associated with a superbubble H II region, DEM 152 in the N44 nebular complex of the Large Magellanic Cloud. With CCD photometry and spectroscopy of the massive stars, we find no evidence that an unusual stellar population gave rise to the shell morphology of the gas. The slope of the initial mass function, {Gamma}=1.3+/-0.2, is consistent with that of other OB associations in the LMC, and there is no significant difference in the initial mass function internal or external to the supershell. The inferred stellar ionizing flux is consistent with the observed nebular H alpha flux. We do find evidence for triggered star formation: the H-R diagram suggests an age of >10Myr for the population interior to the bubble with more recent, <5Myr, star formation on the exterior. Using the detailed data on the stellar population, we compare a numerical form of the Weaver et al. (1977ApJ...218..377W) evolutionary model for wind-driven bubbles with the observed shell kinematics. We find a substantial discrepancy: the observed shell radius is too small and/or expansion velocity too large to be explained with this version of the model. We discuss possible explanations for the inconsistency.
In this series of two papers, we describe a project with the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope (HST) to measure the line-of-sight velocities of stars in the central few arcseconds of the dense globular cluster M15. This first paper focuses on the observations and reduction of the data. We "scanned" the central region of M15 spectroscopically by consecutively placing the 0.1" HST/STIS slit at 18 adjacent positions. The spectral pixel size exceeds the velocity dispersion of M15. This puts the project at the limit of what is feasible with STIS, and exceedingly careful and complicated data reduction and analysis were required.
We present the photometric analysis for the open cluster NGC 7044, based on Johnson-Cousins UBVR CCD photometry of 896 stars in a region of 4'20"x4'20" in the cluster field.
On the basis of its color-magnitude diagram NGC 6528 is one of the two most metal-rich globular clusters that have so far been found in the Galaxy. Such a conclusion is consistent with Morgan's metallic line-strength classification of the integrated spectrum of this cluster. The reddening of NGC 6528 is estimated to be E(B-V)=0.52+/-0.07, from which R=6.1kpc and Z=-0.4kpc.
UBV CCD photometry has been carried out on the heavily reddened (A_V_=6.7) Cepheus open cluster NGC 7419. An age of 14+/-2 Myr and a distance of 2.3kpc have been derived using the isochrones of Maeder. The mass function of the cluster satisfies the Salpeter from n(M)~M^-{gamma}^ with {gamma}=2.25. The cluster is dynamically relaxed.
The table 1 lists photoelectric UBV measures for 78 stars in the open cluster NGC 6025. Distance and age estimates derived are 760pc and 100Myr. The brightest star, HD 143448, is a known emission star and is very probably a member of the cluster. Accurate positions and identifications of the stars were added by B. Skiff (Lowell Observatory) in November 2009.
