- ID:
- ivo://CDS.VizieR/J/ApJ/750/59
- Title:
- BVR polarimetric observations of {beta} Lyr
- Short Name:
- J/ApJ/750/59
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from six years of recalibrated and new spectropolarimetric data taken with the University of Wisconsin's Half-Wave Spectropolarimeter and six years of new data taken with the photoelastic modulating polarimeter at the Flower and Cook Observatory of beta Lyrae. Combining these data with polarimetric data from the literature allows us to characterize the intrinsic BVRI polarized light curves. A repeatable discrepancy of 0.245 days (approximately 6hr) between the secondary minima in the total light curve and the polarization curve in the V band, with similar behavior in the other bands, may represent the first direct evidence for an accretion hot spot on the disk edge.
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- ID:
- ivo://CDS.VizieR/J/A+A/591/A92
- Title:
- BVR polarimetry of HD 48099
- Short Name:
- J/A+A/591/A92
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the structure of the O-type binary system HD 48099 by measuring linear polarization that arises due to light scattering process. High-precision polarimetry provides independent estimates of the orbital parameters and gives important information on the properties of the system. Linear polarization measurements of HD 48099 in the B, V and R passbands with the high-precision Dipol-2 polarimeter have been carried out. The data have been obtained with the 60cm KVA (Observatory Roque de los Muchachos, La Palma, Spain) and T60 (Haleakala, Hawaii, USA) remotely controlled telescopes during 31 observing nights.Polarimetry in the optical wavelengths has been complemented by observations in the X-rays with the SWIFT space observatory. Optical polarimetry revealed small intrinsic polarization in HD 48099 with 0.1% peak to peak variation over the orbital period of 3.08d. The variability pattern is typical for binary systems, showing strong second harmonic of the orbital period. We apply our model code for the electron scattering in the circumstellar matter to put constraints on the system geometry. A good model fit is obtained for scattering of light on a cloud produced by the colliding stellar winds. The geometry of the cloud, with a broad distribution of scattering particles away from the orbital plane, helps in constraining the (low) orbital inclination. We derive from the polarization data the inclination i=17{deg}+/-2{deg} and the longitude of the ascending node Omega=82{deg}+/-1{deg} of the binary orbit. The available X-ray data provide additional evidence for the existence of the colliding stellar winds in the system. Another possible source of the polarized light could be scattering from the stellar photospheres. The models with circumstellar envelopes, or matter confined to the orbital plane, do not provide good constraints on the low inclination, better than i<=27{deg}, as is already suggested by the absence of eclipses.
- ID:
- ivo://CDS.VizieR/J/ApJ/752/42
- Title:
- BV time series in Ursa Major II
- Short Name:
- J/ApJ/752/42
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a B, V color-magnitude diagram (CMD) of the Milky Way dwarf satellite Ursa Major II (UMa II), spanning the magnitude range from V~15 to V~23.5mag and extending over an 18x18 arcmin^2^ area centered on the Galaxy. Our photometry goes down to about 2 mag below the Galaxy's main-sequence turnoff that we detected at V~21.5 mag. We have discovered a bona fide RR Lyrae variable star in UMa II, which we use to estimate a conservative dereddened distance modulus for the galaxy of (m-M)_0_=17.70+/-0.04+/-0.12mag, where the first error accounts for the uncertainties of the calibrated photometry, and the second reflects our lack of information on the metallicity of the star. The corresponding distance to UMa II is 34.7^+0.6^_-0.7_(^+2.0^_-1.9_)kpc. Our photometry shows evidence of a spread in the Galaxy's subgiant branch, compatible with a spread in metal abundance in the range between Z=0.0001 and Z=0.001. Based on our estimate of the distance, a comparison of the fiducial lines of the Galactic globular clusters M68 and M5 ([Fe/H]=-2.27+/-0.04 dex and -1.33+/-0.02 dex, respectively), with the position on the CMD of spectroscopically confirmed Galaxy members, may suggest the existence of stellar populations of different metal abundance/age in the central region of UMa II.
- ID:
- ivo://CDS.VizieR/J/PASJ/65/1
- Title:
- BX Dra BVR differential light curves
- Short Name:
- J/PASJ/65/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New CCD photometric observations of BX Dra were carried out on 26 nights during the period from 2009 April to 2010 June. The long-term photometric behaviors of the system are obtained from detailed studies of the period and light variations, based on historical data and our new observations.
- ID:
- ivo://CDS.VizieR/J/ApJS/161/118
- Title:
- byH{alpha} photometry in open clusters
- Short Name:
- J/ApJS/161/118
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Be stars are a class of rapidly rotating B stars with circumstellar disks that cause Balmer and other line emission. There are three possible reasons for the rapid rotation of Be stars: they may have been born as rapid rotators, spun up by binary mass transfer, or spun up during the main-sequence (MS) evolution of B stars. To test the various formation scenarios, we have conducted a photometric survey of 55 open clusters in the southern sky. Of these, five clusters are probably not physically associated groups and our results for two other clusters are not reliable, but we identify 52 definite Be stars and an additional 129 Be candidates in the remaining clusters.
- ID:
- ivo://CDS.VizieR/J/ApJ/622/1052
- Title:
- byH{alpha} photometry of NGC 3766
- Short Name:
- J/ApJ/622/1052
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe a technique to identify Be stars in open clusters using Stroemgren b, y, and narrowband H{alpha} photometry. We first identify the B-type stars of the cluster using a theoretical isochrone fit to the (b-y, y) color-magnitude diagram. The strongest Be stars are easily identified in a (b-y, y-H{alpha}) color-color diagram, but those with weaker H{alpha} emission (classified as possible Be star detections) may be confused with evolved or foreground stars. Here we present such photometry plus H{alpha} spectroscopy of members of the cluster NGC 3766 to demonstrate the accuracy of our technique.
- ID:
- ivo://nasa.heasarc/bhrfscid
- Title:
- Byurakan/Hamburg/ROSAT Catalog of Optical IDs
- Short Name:
- BHROSATOpt.
- Date:
- 09 May 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains the Byurakan/Hamburg/ROSAT Catalog (BHRC) of the optical identifications of X-ray sources. The BHRC includes all 2791 X-ray sources from the ROSAT Faint Source Catalog (ROSAT-FSC, CDS Catalog <IX/29>) with galactic latitude |b| >= 30 degrees, declination >= 0 degrees, and ROSAT PSPC count rate CR > 0.04 ct/s. The optical identifications were carried out using the Hamburg Quasar Survey (HQS) digitized spectroscopic plates, the DSS1 and DSS2 (blue, red, and IR) images, the MAPS photometric data, the USNO-B1.0 (for proper motion), the NVSS and FIRST radio, and the IRAS and 2MASS infrared catalogs. From the DSS images, positional, brightness, color, extension, variability, and proper-motion information, the optical-to-X-ray positional offsets were obtained and a morphological classification was made. Available SIMBAD and NED data were also utilized. Cross-correlations were made with AGN, white dwarf, and cataclysmic variable catalogs (322, 8 and 7 associations, respectively). The authors managed to identify 97% of the sources (2696/2791 sources) that are associated with 3202 optical objects. 2248 X-ray sources have a single optical counterpart, 144 have a double or multiple optical counterpart (binaries, galaxy groups, etc.), and 304 have ambiguous identifications (some of the latter might actually be blends of two X-ray sources that were not resolved by ROSAT). The QSOs and AGN represent the largest group of X-ray counterparts (56.2%); bright stars (including late-type stars, but excluding WDs and CVs) are counterparts for 33.2% of the sources, and bright galaxies and groups of galaxies comprise 9.2%. A number of close galaxy pairs (possibly interacting/merging galaxies) are found as counterparts for X-ray sources (3.0%), as well as 1.0% WDs and 0.4% CVs. The BHRC may be used for the selection and study of samples of the various classes of X-ray emitters: the table gives all the available multiwavelength data for the identified sources. This table was created by the HEASARC in June 2006 based on CDS table J/A+A/449/425/table1.dat This is a service provided by NASA HEASARC .
- ID:
- ivo://CDS.VizieR/J/PAZh/44/383
- Title:
- Byurakan-IRAS galaxies (BIG) with SDSS spectra
- Short Name:
- J/PAZh/44/383
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The sample of Byurakan-IRAS galaxies (BIG) has been created based on optical identifications of IRAS Point Source Catalog (PSC) at high galactic latitudes. As a result, 1178 galaxies have been identified. 172 of them have been observed spectroscopically with Byurakan Astrophysical Observatory (BAO, Armenia) 2.6m, Special Astrophysical Observatory (SAO, Russia) 6m and Observatoire de Haute Provence (OHP, France) 1.93m telescopes. Later on, spectra were obtained for more 83 BIG objects in Sloan Digital Sky Survey (SDSS). We have extracted and studied these spectra, classified them and measured spectral features. Diagnostic diagrams have been built to distinguish starbursts (SB), LINERs and Seyfert galaxies. Cross-correlations were made for these objects with multiwavelength (MW) catalogues and their physical properties were studied. Among these 83 objects, 55 HII, 8 Seyfert galaxies, 2 LINERs, 4 other AGN, 6 composite spectrum objects, and 8 other emission-line galaxies have been revealed. Three of these objects are Ultra-Luminous InfraRed Galaxies (ULIRG).
- ID:
- ivo://CDS.VizieR/J/A+A/507/131
- Title:
- BzJK observations around radio galaxies
- Short Name:
- J/A+A/507/131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore the environments of two radio galaxies at z~1.5, 7C 1751+6809 and 7C 1756+6520, using deep optical and near-infrared imaging. Our data cover 15x15arcmin^2^ fields around the radio galaxies. We develop and apply BzK color criteria to select cluster member candidates around the radio galaxies and find no evidence of an overdensity of red galaxies within 2Mpc of 7C 1751+6809. In contrast, 7C 1756+6520 shows a significant overdensity of red galaxies within 2Mpc of the radio galaxy, by a factor of 3.1+/-0.8 relative to the four MUSYC fields. At small separation (r<6"), this radio galaxy also has one z>1.4 evolved galaxy candidate, one z>1.4 star-forming galaxy candidate, and an AGN candidate (at indeterminate redshift).
- ID:
- ivo://CDS.VizieR/J/ApJ/462/241
- Title:
- Ca abundance for Omega Cen red giants
- Short Name:
- J/ApJ/462/241
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an unbiased catalog of calcium abundances for 517 red giants brighter than M_V_~-1 in the chemically inhomogeneous globular cluster omega Centauri. The basic features of the abundance distribution are as follows: (1) few, if any, stars exist on the giant branch of omega Cen with [Ca/H] less than -1.6; (2) there is a well-defined peak in the distribution at [Ca/H]=-1.4, with a long tail stretching up to ~[Ca/H]~-0.3; and (3) the distribution is bimodal with a second smaller peak in the distribution at [Ca/H]=-0.9.
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