- ID:
- ivo://CDS.VizieR/V/109
- Title:
- SKY2000 Catalog, Version 4
- Short Name:
- V/109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The SKYMAP Star Catalog System consists of a Master Catalog stellar database and a collection of utility software designed to create and maintain the database and to generate derivative mission star catalogs (run catalogs). It contains an extensive compilation of information on almost 300000 stars brighter than 8.0 mag. The original SKYMAP Master Catalog was generated in the early 1970's. Incremental updates and corrections were made over the following years but the first complete revision of the source data occurred with Version 4.0. This revision also produced a unique, consolidated source of astrometric information which can be used by the astronomical community. The derived quantities were removed and wideband and photometric data in the R (red) and I (infrared) systems were added. Version 4 of the SKY2000 Master Catalog was completed in April 2002; it marks the global replacement of the variability identifier and variability data fields. More details can be found in the description file sky2kv4.pdf. This version supersedes the previous versions 1(V/95), 2(V/102), and 3(V/105).
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- ID:
- ivo://CDS.VizieR/V/145
- Title:
- SKY2000 Master Catalog, Version 5
- Short Name:
- V/145
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The SKYMAP Star Catalog System consists of a Master Catalog stellar database and a collection of utility software designed to create and maintain the database and to generate derivative mission star catalogs (run catalogs). It contains an extensive compilation of information on almost 300000 stars brighter than 8.0mag. The original SKYMAP Master Catalog was generated in the early 1970's. Incremental updates and corrections were made over the following years but the first complete revision of the source data occurred with Version 4.0. This revision also produced a unique, consolidated source of astrometric information which can be used by the astronomical community. The derived quantities were removed and wideband and photometric data in the R (red) and I (infrared) systems were added. Version 4 of the SKY2000 Master Catalog was completed in April 2002; it marks the global replacement of the variability identifier and variability data fields. More details can be found in the description file sky2kv4.pdf. The SKY2000 Version 5 Revision 4 Master Catalog differs from Revision 3 in that MK and HD spectral types have been added from the Catalogue of Stellar Spectral Classifications (B. A. Skiff of Lowell Observatory, 2005), which has been assigned source code 50 in this process. 9622 entries now have MK types from this source, while 3976 entries have HD types from this source. SKY2000 V5 R4 also differs globally from preceding MC versions in that the Galactic coordinate computations performed by UPDATE have been increased in accuracy, so that differences from the same quantities from other sources are now typically in the last decimal places carried in the MC. This version supersedes the previous versions 1(V/95), 2(V/102), 3(V/105) and 4(V/109).
- ID:
- ivo://CDS.VizieR/V/95
- Title:
- SKY2000 - Master Star Catalog
- Short Name:
- V/95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The SKYMAP Star Catalog System consists of a Master Catalog stellar database and a collection of utility software designed to create and maintain the database and to generate derivative mission star catalogs (run catalogs). It contains an extensive compilation of information on almost 300000 stars.
- ID:
- ivo://CDS.VizieR/V/102
- Title:
- SKY2000 - Master Star Catalog, Version 2
- Short Name:
- V/102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The SKYMAP Star Catalog System consists of a Master Catalog stellar database and a collection of utility software designed to create and maintain the database and to generate derivative mission star catalogs (run catalogs). It contains an extensive compilation of information on almost 300000 stars brighter than 8.0 mag.
- ID:
- ivo://CDS.VizieR/VIII/45
- Title:
- Southern flat-spectrum sources
- Short Name:
- VIII/45
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Optical identifications have been sought for 198 southern radio sources (73 in Paper I, 06h<RA(B1950)<18h and 125 in Paper II, 18h<RA(B1950)<06h) using new positions determined with the six-dish array of the Fleurs synthesis telescope. These sources constitute a complete sample drawn from the Parkes 2700-MHz catalogue. They are all flat-spectrum sources stronger than 0.25 Jy at 2700 MHz and lie between Dec(B1950) -80 and -50{deg}. Sources with |b|<5{deg} are not included. The new radio positions have standard deviations of about 1'' (2'' in Paper I, 1'' in Paper II) in right ascension and declination. The optical positions are with respect to the FK4 reference system as defined by the Perth catalogues and have position uncertainties of about 0.5arcsec. Magnitude estimates are on the J scale and are accurate to about 0.4mag for stellar-like objects and 0.5 to 1.0mag for galaxies. The sample is complete to the 22.5-mag limit of the SERC-J sky atlas. There are 198 sources in the complete sample. 31 sources (16%) show some radio structure with the 2'' beam. For the 175 unresolved sources, there are 124 QSOs (71%), 26 galaxies (15%) and 25 empty fields (14%) suggested.
- ID:
- ivo://CDS.VizieR/J/AJ/150/16
- Title:
- Speckle-interferometry in Melotte 111
- Short Name:
- J/AJ/150/16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a high-angular resolution survey for the search of binary and multiple stars in the Galactic open cluster Melotte 111. Combining our own speckle-interferometric observations with data taken from the literature, we found a ratio of the number of single to multiple stars to be 29:8:0:0:0:1 for the most probable members, indicating a multiplicity fraction for this cluster of 25.6%+/-2%. We also observed field stars in the vicinity of the cluster and estimated a ratio of multiplicities of 286:17:1:0:0:0:1 (between one and seven companions), equivalent to a multiplicity fraction of 5.9%+/-3%. We showed that the cumulative distribution of separations for our sample stars is in agreement with Opik's law.
- ID:
- ivo://CDS.VizieR/J/ApJS/224/26
- Title:
- Spectral energy distributions of Roma BZCAT blazars
- Short Name:
- J/ApJS/224/26
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We combined multi-wavelength data for blazars from the Roma-BZCAT catalog and analyzed hundreds of X-ray spectra. We present the fluxes and spectral energy distributions (SEDs), in 12 frequency bands from radio to {gamma}-rays, for a final sample of 2214 blazars. Using a model-independent statistical approach, we looked for systematic trends in the SEDs; the most significant trends involved the radio luminosities and X-ray spectral indices of the blazars. We used a principal component analysis (PCA) to determine the basis vectors of the blazar SEDs and, in order to maximize the size of the sample, imputed missing fluxes using the K-nearest neighbors method. Using more than an order of magnitude more data than was available when Fossati et al. first reported trends of SED shape with blazar luminosity, we confirmed the anti-correlation between radio luminosity and synchrotron peak frequency, although with greater scatter than was seen in the smaller sample. The same trend can be seen between bolometric luminosity and synchrotron peak frequency. Finally, we used all of the available blazar data to determine an empirical SED description that depends only on the radio luminosity at 1.4GHz and the redshift. We verified that this statistically significant relation was not a result of the luminosity-luminosity correlations that are natural in flux-limited samples (i.e., where the correlation is actually caused by the redshift rather than the luminosity).
- ID:
- ivo://CDS.VizieR/J/ApJ/691/672
- Title:
- Spectrocopy of YSOs in Serpens molecular cloud
- Short Name:
- J/ApJ/691/672
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the results of an optical spectroscopic survey designed to confirm the youth and determine the spectral types among a sample of young stellar object (YSO) candidates in the Serpens molecular cloud. We observed 150 infrared (IR) excess objects previously discovered by the Spitzer Legacy Program "From Molecular Cores to Planet-Forming Disks" (c2d), bright enough for subsequent Spitzer/InfraRed Spectrograph (IRS) spectroscopy. We obtained 78 optical spectra of sufficient signal-to-noise for analysis. Extinctions, effective temperatures, and luminosities are estimated for this sample, and used to construct Hertzsprung-Russell (H-R) diagrams for the population. We identified 20 background giants contaminating the sample, based on their relatively high extinction, position in the H-R diagram, the lack of H{alpha} emission and relatively low IR excess. Such strong background contamination (25%) is consistent with the location of Serpens being close to the Galactic plane (5{deg} Galactic latitude). The remaining 58 stars (75%) were all confirmed to be young, mostly K- and M-type stars that are presumed to belong to the cloud. Our analysis shows that the majority of the IR excess objects detected in Serpens are actively accreting, young T-Tauri stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/842/97
- Title:
- Spectroscopic obs. of 413 HII regions in M33
- Short Name:
- J/ApJ/842/97
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The spectra of 413 star-forming (or H II) regions in M33 (NGC 598) were observed using the multifiber spectrograph of Hectospec at the 6.5m Multiple Mirror Telescope. Using this homogeneous spectra sample, we measured the intensities of emission lines and some physical parameters, such as electron temperatures, electron densities, and metallicities. Oxygen abundances were derived via the direct method (when available) and two empirical strong-line methods, namely, O3N2 and N2. At the high-metallicity end, oxygen abundances derived from the O3N2 calibration were higher than those derived from the N2 index, indicating an inconsistency between O3N2 and N2 calibrations. We present a detailed analysis of the spatial distribution of gas-phase oxygen abundances in M33 and confirm the existence of the axisymmetric global metallicity distribution that is widely assumed in the literature. Local variations were also observed and subsequently associated with spiral structures to provide evidence of radial migration driven by arms. Our O/H gradient fitted out to 1.1 R_25_ resulted in slopes of -0.17+/-0.03, -0.19+/-0.01, and -0.16+/-0.17dex R_25_^-1^, utilizing abundances from O3N2, N2 diagnostics, and a direct method, respectively.
- ID:
- ivo://CDS.VizieR/J/AJ/145/125
- Title:
- Spectroscopy and HST photometry in Westerlund 2
- Short Name:
- J/AJ/145/125
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a spectroscopic and photometric determination of the distance to the young Galactic open cluster Westerlund 2 using WFPC2 imaging from the Hubble Space Telescope (HST) and ground-based optical spectroscopy. HST imaging in the F336W, F439W, F555W, and F814W filters resolved many sources previously undetected in ground-based observations and yielded photometry for 1136 stars. We identified 15 new O-type stars, along with two probable binary systems, including MSP188 (O3+O5.5). We fit reddened spectral energy distributions based on the Padova isochrones to the photometric data to determine individual reddening parameters R_V_ and A_V_for O-type stars in Wd2. We find average values <R_V_>=3.77+/-0.09 and <A_V_>=6.51+/-0.38mag, which result in a smaller distance than most other spectroscopic and photometric studies. After a statistical distance correction accounting for close unresolved binaries (factor of 1.08), our spectroscopic and photometric data on 29 O-type stars yield that Westerlund 2 has a distance <d>=4.16+/-0.07(random)+0.26(systematic)kpc. The cluster's age remains poorly constrained, with an upper limit of 3Myr. Finally, we report evidence of a faint mid-IR polycyclic aromatic hydrocarbon ring surrounding the well-known binary candidate MSP 18, which appears to lie at the center of a secondary stellar grouping within Westerlund 2.
