- ID:
- ivo://CDS.VizieR/VI/19
- Title:
- UBV Photoelectric Sequences in SA 92-115
- Short Name:
- VI/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The UBV system was originally defined by ten bright standard stars, primarily in the northern sky. These stars are too bright to be used with large telescopes and cannot be reached from southern observatories. This catalog is a careful compilation of data on fainter stars in the equatorial Selected Areas. They are intended as a new set of standards which can be used to define the UBV system at fainter magnitudes in both hemispheres. The stars range in V between 6.0 and 14.9 with most between 9.0 and 13.0.
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- ID:
- ivo://CDS.VizieR/J/ApJ/541/841
- Title:
- UBV photometry and ages of Trapezium systems
- Short Name:
- J/ApJ/541/841
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We sought to determine the maximum age of Trapezium systems by studying possible trapezium systems that were selected independently of their occurrence in H II regions. We started with the unpublished catalog by Allen, Tapia & Parrao (1977RMxAA...3..119A) of all the known visual systems having three or more stars in which the maximum separation is less than 3.0 times the minimum separation. Their catalog has 968 such systems whose most frequent primary type is F, which does not describe young systems. With a CCD on the Kitt Peak 0.9m telescope we obtained UBV frames for 265 systems accessible with our equipment on Kitt Peak. The frames were used to obtain UBV photometry for about 1500 stars with an accuracy of 0.04mag between V=7 and 14mag. Also these frames were used to obtain astrometry with an accuracy of +/-0.015{deg} in position angle and +/-0.01" in separation. For the brightest star in each system we obtained a spectral type to determine the distance and reddening to the system.
- ID:
- ivo://CDS.VizieR/II/248
- Title:
- UBV photometry and proper motions in M13
- Short Name:
- II/248
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The first epoch plates of 8 globular clusters, available in the plate collection of the Pulkovo Observatory, were taken with the normal astrograph at the end of the last and beginning of this century. These plates had been measured previously by N. Gamalei [1948, IzPul, 141] in order to determine the proper motions of the clusters. From 40 to 62 stars were used for this purpose and these were assumed to be cluster members on the basis of their proximity to the cluster centers. The epoch differences ranged from 30 to 45 years. As this time interval has now increased considerably (by about a factor of two), it is planned to redetermine the proper motions of these clusters, using more precise criteria for the selection of stars belonging to the cluster. In the previous study (N. Gamalei [1948, IzPul, 141]) only a limited number of field reference stars were measured, and as more complete data on the cluster, cluster members and field stars is desirable all the star images on the plates in an area 80'x80' will be measured in the present program. For future studies of the orbits of galactic clusters it is important that the absolute proper motions be on one system and therefore special attention should be devoted to this problem. The present paper is a continuation of an investigation of M13 and deals with the determination of the proper motions and U, B, V magnitudes of separate stars and also a redetermination of the proper motions of the cluster. The U, B, V magnitudes of the majority of 923 stars with measured proper motions were found from plates (table 2) taken with the 2 meter Schmidt telescope at Tautenburg and kindly lent to us by Professor N. Richter. The photoelectric standards as given by Savedoff [1956AJ.....61..254S] (table 7) and also U B V magnitudes of six bright field stars (table 8) observed by Mayer were used for calibration. A comparison of the determined B and V magnitudes of stars within an area of about 10'x10' centered on the cluster with those obtained by other authors indicates that the probable external errors do not exceed +/-0.03mag (table 15). However as the photoelectric magnitudes of fainter field stars were not available, a slight systematic error may be present in the derived magnitudes of these stars. Data on the plates used for the determination of the proper motions were given in Kadla [1963AZh....40..691K]. The relative proper motion of M 13, redetermined on the basis of a larger number of cluster members (80 in all, measured on 4 pairs of plates with a mean epoch difference equal to 61.4 years) is found to be {mu}x=+0.0008", {mu}y=-0.0014" with a probable error of +/-0.0002".
- ID:
- ivo://CDS.VizieR/J/PASP/102/1392
- Title:
- UBV photometry from HK survey. I
- Short Name:
- J/PASP/102/1392
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 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).
- 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.
14616. 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.
14617. 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.
14618. 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.
14619. 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.
- 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.
