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- ID:
- ivo://CDS.VizieR/J/A+A/610/A30
- Title:
- B stars in 4 open clusters
- Short Name:
- J/A+A/610/A30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Stellar physical properties of star clusters are poorly known and the cluster parameters are often very uncertain. Our goals are to perform a spectrophotometric study of the B star population in open clusters to derive accurate stellar parameters, search for the presence of circumstellar envelopes, and discuss the characteristics of these stars. The BCD spectrophotometric system is a powerful method to obtain stellar fundamental parameters from direct measurements of the Balmer discontinuity. To this end, we wrote the interactive code MIDE3700. The BCD parameters can also be used to infer the main properties of open clusters: distance modulus, color excess, and age. Furthermore, we inspected the Balmer discontinuity to provide evidence for the presence of circumstellar disks and identify Be star candidates. We used an additional set of high-resolution spectra in the H{alpha} region to confirm the Be nature of these stars. We provide Teff, logg, Mv, Mbol, and spectral types for a sample of 68 stars in the field of the open clusters NGC6087, NGC6250, NGC6383, and NGC6530, as well as the cluster distances, ages, and reddening. Then, based on a sample of 230 B stars in the direction of the 11 open clusters studied along this series of three papers, we report 6 new Be stars, 4 blue straggler candidates, and 15 B-type stars (called Bdd) with a double Balmer discontinuity, which indicates the presence of circumstellar envelopes. We discuss the distribution of the fraction of B, Be, and Bdd star cluster members per spectral subtype. The majority of the Be stars are dwarfs and present a maximum at the spectral type B2-B4 in young and intermediate-age open clusters (<40Myr). Another maximum of Be stars is observed at the spectral type B6-B8 in open clusters older than 40Myr, where the population of Bdd stars also becomes relevant. The Bdd stars seem to be in a passive emission phase. Our results support previous statements that the Be phenomenon is present along the whole main sequence band and occurs in very different evolutionary states.We find clear evidence of an increase of stars with circumstellar envelopes with cluster age. The Be phenomenon reaches its maximum in clusters of intermediate age (10-40Myr) and the number of B stars with circumstellar envelopes (Be plus Bdd stars) is also high for the older clusters (40-100Myr).
- ID:
- ivo://CDS.VizieR/J/other/ApSS/203.53
- Title:
- B stars UBV and SpType catalogue
- Short Name:
- J/other/ApSS/203
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The present work represents a catalogue of spectral classification and photometric data of 2047 B type stars using the {Delta}Q method.
- ID:
- ivo://CDS.VizieR/J/A+AS/122/51
- Title:
- B to G stars calibration in Geneva photometry
- Short Name:
- J/A+AS/122/51
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used recent Kurucz models and many standard stars to revise previous calibrations of the Geneva photometric parameters in terms of Teff, logg, and [M/H]. In addition, new parameters pT and pG were defined, which are the Geneva equivalents of Stromgren's a and r parameters and allow to estimate Teff and logg for stars with intermediate temperature (spectral type A0-A3). A fortran code (calib.f) has been written, which applies our calibration to stars measured in the Geneva system. A conspicuous change in slope appears in the grid d vs B2-V1. It seems to be linked with the onset of convection in the superficial layers of the star's envelope.
- ID:
- ivo://CDS.VizieR/J/A+A/434/1125
- Title:
- B-type Supergiants in the SMC
- Short Name:
- J/A+A/434/1125
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High-resolution UCLES/AAT spectra are presented for nine B-type supergiants in the SMC, chosen on the basis that they may show varying amounts of nuclear-synthetically processed material mixed to their surface. These spectra have been analysed using a new grid of approximately 12000 non-LTE line blanketed TLUSTY model atmospheres to estimate atmospheric parameters and chemical composition.
- ID:
- ivo://CDS.VizieR/J/A+A/606/A8
- Title:
- Bubble HII region Sh2-39 (N5)
- Short Name:
- J/A+A/606/A8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Aiming at studying the physical properties of Galactic IR bubbles and to explore their impact in triggering massive star formation, we perform a multiwavelength analysis of the bubble HII region Sh2-39 (N5) and its environs. To analyze the molecular gas we use CO(3-2) and HCO^+^(4-3) line data obtained with the on-the-fly technique from the ASTE telescope. To study the distribution and physical characteristics of the dust, we make use of archival data from ATLASGAL, Herschel, and MSX, while the ionized gas was studied making use of an NVSS image. We use public WISE, Spitzer, and MSX point source catalogs to search for infrared candidate YSOs in the region. To investigate the stellar cluster [BDS2003] 6 we use IR spectroscopic data obtained with the ARCoIRIS spectrograph, mounted on Blanco 4-m Telescope at CTIO, and new available IR Ks band observations from the VVVeXtended ESO Public Survey (VVVX). The new ASTE observations allowed the molecular gas component in the velocity range from 30km/s to 46km/s, associated with Sh2-39, to be studied in detail. The morphology of the molecular gas suggests that the ionized gas is expanding against its parental cloud. We have identified four molecular clumps, that were likely formed by the expansion of the ionization front, and determined some of their physical and dynamical properties. Clumps having HCO^+^ and 870um counterparts show evidence of gravitational collapse. We identified several candidate YSOs across the molecular component. Their spatial distribution, as well as the fragmentation time derived for the collected layers of the molecular gas, suggest that massive star formation might have been triggered by the expansion of the nebula via the collect and collapse mechanism. The spectroscopical distance obtained for the stellar cluster [BDS2003] 6, placed over one of the collapsing clumps in the border of the HII region, reveals that this cluster is physically associated with the nebula and gives more support to the triggered massive star formation scenario. A radio continuum data analysis indicates that the nebula is older and expands at lower velocity than typical IR Galactic bubbles.
- ID:
- ivo://CDS.VizieR/J/ApJ/649/759
- Title:
- Bubbles in the galactic disk
- Short Name:
- J/ApJ/649/759
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A visual examination of the images from the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) has revealed 322 partial and closed rings that we propose represent partially or fully enclosed three-dimensional bubbles. We argue that the bubbles are primarily formed by hot young stars in massive star formation regions. We have found an average of about 1.5 bubbles per square degree. About 25% of the bubbles coincide with known radio HII regions, and about 13% enclose known star clusters. It appears that B4B9 stars (too cool to produce detectable radio HII regions) probably produce about three-quarters of the bubbles in our sample, and the remainder are produced by young OB3 stars that produce detectable radio HII regions.
- ID:
- ivo://CDS.VizieR/J/ApJ/670/428
- Title:
- Bubbles in the galactic disk. II.
- Short Name:
- J/ApJ/670/428
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report 269 mid-infrared bubbles within 10{deg} of the Galactic center from visual inspection of the Spitzer GLIMPSE II Legacy Science program images. The surface density of bubbles is ~5deg^-2^ or about 3 times that detected in longitudes |l|=10{deg}-65{deg}, because the inner 10{deg} of longitude were more thoroughly searched for small bubbles. There is a gradient in the number of bubbles with longitude with an increase of about a factor of 2 from 2{deg} to 10{deg}; this is probably the result of several factors, including decreasing diffuse background brightness, confusion, and opacity with longitude. Bubble eccentricities are typically between 0.6 and 0.8, and >50% show evidence for blowouts, which we suggest result from local density fluctuations of the ISM and/or anisotropic stellar winds and radiation fields.
- ID:
- ivo://CDS.VizieR/I/31
- Title:
- Bucharest KSZ Faint Stars, -11 to +11, 1950.0
- Short Name:
- I/31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog contains the results of the differential observations of 3939 stars made with the Transit Circle of the Bucharest Observatory, from 1955 July 1 to 1962 June 16. The positions were observed simultaneously with the Catalog of the Southern Reference Star program. 105 stars were selected to be near extragalactic nebulae; the remaining 3852 stars were from the KSZ list. The positions are on the FK3R system for the equinox, 1950.0. Mean errors are 0.029s and 0.49" in right ascension and declination, respectively. The catalog contains for each star, in addition to the positions: the BD number, magnitude, spectral type, individual mean errors, epoch of the observations, number of observations in each coordinate, number of the star in the list of areas near extragalactic nebulae, and notes.
- ID:
- ivo://CDS.VizieR/J/MNRAS/393/1531
- Title:
- BUDDA structural properties of galaxies
- Short Name:
- J/MNRAS/393/1531
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have performed 2D bulge/bar/disc decompositions using g, r and i-band images of a representative sample of nearly 1000 galaxies from the Sloan Digital Sky Survey. We show that the Petrosian concentration index is a better proxy for the bulge-to-total ratio than the global Sersic index. We show that pseudo-bulges can be distinguished from classical bulges as outliers in the Kormendy relation. We provide the structural parameters and distributions of stellar masses of ellipticals, classical bulges, pseudo-bulges, discs and bars, and find that 32% of the total stellar mass in massive galaxies in the local universe is contained in ellipticals, 36% in discs, 25% in classical bulges, 3% in pseudo-bulges and 4% in bars.
