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7121. UBV photometry in Berkeley 32
ID:
ivo://CDS.VizieR/J/AcA/41/167
Title:
UBV photometry in Berkeley 32
Short Name:
J/AcA/41/167
Date:
21 Oct 2021
Publisher:
CDS
Description:
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.
7122. UBV photometry in 5 fields of the LMC
ID:
ivo://CDS.VizieR/J/AJ/116/1275
Title:
UBV photometry in 5 fields of the LMC
Short Name:
J/AJ/116/1275
Date:
21 Oct 2021
Publisher:
CDS
Description:
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.
7123. UBV photometry in LH 47/48
ID:
ivo://CDS.VizieR/J/ApJ/452/210
Title:
UBV photometry in LH 47/48
Short Name:
J/ApJ/452/210
Date:
21 Oct 2021
Publisher:
CDS
Description:
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.
7124. UBV photometry in M15
ID:
ivo://CDS.VizieR/J/AJ/124/3255
Title:
UBV photometry in M15
Short Name:
J/AJ/124/3255
Date:
21 Oct 2021
Publisher:
CDS
Description:
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.
7125. UBV photometry in NGC 7044
ID:
ivo://CDS.VizieR/J/AJ/106/1547
Title:
UBV photometry in NGC 7044
Short Name:
J/AJ/106/1547
Date:
21 Oct 2021
Publisher:
CDS
Description:
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.
7126. UBV photometry in NGC 6528
ID:
ivo://CDS.VizieR/J/AJ/84/1305
Title:
UBV photometry in NGC 6528
Short Name:
J/AJ/84/1305
Date:
21 Oct 2021
Publisher:
CDS
Description:
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.
7127. UBV Photometry in NGC 7419
ID:
ivo://CDS.VizieR/J/ApJS/93/187
Title:
UBV Photometry in NGC 7419
Short Name:
J/ApJS/93/187
Date:
21 Oct 2021
Publisher:
CDS
Description:
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.
7128. UBV photometry in NGC 6025
ID:
ivo://CDS.VizieR/J/PASP/83/800
Title:
UBV photometry in NGC 6025
Short Name:
J/PASP/83/800
Date:
21 Oct 2021
Publisher:
CDS
Description:
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.
7129. UBV photometry in NGC 6822, M31 and M33
ID:
ivo://CDS.VizieR/J/AJ/110/2715
Title:
UBV photometry in NGC 6822, M31 and M33
Short Name:
J/AJ/110/2715
Date:
21 Oct 2021
Publisher:
CDS
Description:
We investigate the massive star content of the three Local Group galaxies NGC 6822, M31, and M33 using crowded-field CCD UBV photometry in selected regions to identify the most luminous and massive stars. Optical spectroscopy is presented for many of these stars, allowing construction of accurate H-R diagrams and the first meaningful characterization of the massive star populations in these galaxies. The spectral types also allow investigation of the internal reddenings within these systems and provide fine candidates for stellar-wind studies in the UV. The early-type stars identified include O-type in all three systems, and we call attention to a new Luminous Blue Variable candidate in M33. Our spectroscopy of extreme B supergiants (M_V=-7.5) shows the expected changes with metallicity in comparison to similar objects in the Milky Way, LMC, and SMC, although the metal lines in the NGC 6822 stars are considerably weaker than that expected for a metallicity intermediate between that of the LMC and SMC, suggesting that this galaxy is more metal poor than usually supposed. There is considerable internal reddening within all three galaxies, including even the dwarf irregular NGC 6822, where the color excesses show a systematic spatial trend from E(B-V)=0.26 near the edges to 0.45 in the middle. The slope of the reddening curve is normal in NGC 6822 and M33, with E(U-B)/E(B-V)~0.72, but in M31 we find that this ratio is 0.4-0.5 in all three of our fields. We spectroscopically confirm that stars of high mass (>80M_{sun}_) and luminosity (Mbol~-11) are found in M31 and M33. We have not found stars of similar high mass or luminosity in NGC 6822, where the most luminous star present has Mbol=-10 and an inferred mass of 60M_{sun}_. Similarly, none of the OB associations in NGC 6822 are as impressive in terms of the number of massive stars as the rich associations of the Milky Way and Magellanic Clouds. However, OB78 (=NGC 206) and OB48 in M31 both contain 9-15 stars of mass >40M_{sun}_, making them comparable to impressive sites of star formation in the Milky Way and Magellanic Clouds. M33 contains regions that are even more extreme, with M33-OB127 and M33-OB21 containing 20-30 such stars. The low number of very massive stars in NGC 6822 is consistent with the overall star-formation rate inferred by other means, but the M33 results suggest that the formation of high-mass stars may be favored. The massive star content of individual associations would not have been inferred on the basis of Halpha flux, meaning that the nebulae associated with a number of these OB associations are density rather than radiation bounded, probably due to holes blown in the H I. We have also found that the ratio of the number of very massive (>40M_{sun}_) stars to the number of WR stars is constant within all the Local Group galaxies we have studied, suggesting that (a) the effect of metallicity on the evolution of massive stars is subtle if present, and (b) that WR stars make excellent tracers of the massive star populations. The fact that this ratio is roughly 3, rather than the 10 expected given the relative H- and He-burning lifetimes, argues that either our samples are (uniformly?) incomplete or that some fraction of WR stars are H-burning objects.
7130. UBV photometry in open cluster NGC 2539
ID:
ivo://CDS.VizieR/J/A+A/361/945
Title:
UBV photometry in open cluster NGC 2539
Short Name:
J/A+A/361/945
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present UBV photoelectric observations of 345 stars in the field of the southern open cluster NGC 2539. The analysis of these data allows to determine that 169 stars are probable members of the cluster main sequence, while 23 are possible members.