- ID:
- ivo://CDS.VizieR/V/132
- Title:
- SAI Open Clusters Catalog
- Short Name:
- V/132
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The automated search for star clusters of J,H,K_s data from the Two Micron All-Sky Survey (2MASS) was made using a new method based on the convolution with density functions (Koposov et al. 2008A&A...486..771K). In two papers (this one and Koposov et al. 2008A), 168 new clusters were found and verified in the range of galactic latitude |b|<24 degrees. The new method to estimate main physical parameters of clusters was developed, which involves three different techniques: Hess-diagram, color-magnitude diagrams in (J,J-H) and (K_s,J-K_s), and radial density distribution. Color excesses E(B-V), distance moduli and ages were determined for 141 new and 27 known, but poorly studied clusters. We present the Sternberg Astronomical Institute Open Clusters Catalog (SAI OCL Catalog) of coordinates, diameters and main physical parameters of these clusters. The parameters for 9 clusters were determined using J,H,K data from UKIDSS GPS. For 26 new embedded clusters, we publish the coordinates and diameters only. To facilitate the access to these data and its scientific analysis, we have developed a dedicated web-site of the catalog available at http://ocl.sai.msu.ru/
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/468/250
- Title:
- SCUBA-2 Ambitious Sky Survey
- Short Name:
- J/MNRAS/468/250
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The SCUBA-2 Ambitious Sky Survey (SASSy) is composed of shallow 850-{mu}m imaging using the Submillimetre Common-User Bolometer Array 2 (SCUBA-2) on the James Clerk Maxwell Telescope. Here we describe the extraction of a catalogue of beam-sized sources from a roughly 120deg^2^ region of the Galactic plane mapped uniformly (to an rms level of about 40mJy), covering longitude 120{deg}<l<140{deg} and latitude |b|<2.9{deg}. We used a matched-filtering approach to increase the signal-to-noise ratio (S/N) in these noisy maps and tested the efficiency of our extraction procedure through estimates of the false discovery rate, as well as by adding artificial sources to the real images. The primary catalogue contains a total of 189 sources at 850{mu}m, down to an S/N threshold of approximately 4.6. Additionally, we list 136 sources detected down to S/N=4.3, but recognize that as we go lower in S/N, the reliability of the catalogue rapidly diminishes. We perform follow-up observations of some of our lower significance sources through small targeted SCUBA-2 images and list 265 sources detected in these maps down to S/N=5. This illustrates the real power of SASSy: inspecting the shallow maps for regions of 850-{mu}m emission and then using deeper targeted images to efficiently find fainter sources. We also perform a comparison of the SASSy sources with the Planck Catalogue of Compact Sources and the IRAS Point Source Catalogue, to determine which sources discovered in this field might be new, and hence potentially cold regions at an early stage of star formation.
- ID:
- ivo://CDS.VizieR/J/ApJ/738/79
- Title:
- SDSS-DR8 BHB stars in the Milky Way's halo
- Short Name:
- J/ApJ/738/79
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present and analyze the positions, distances, and radial velocities for over 4000 blue horizontal-branch (BHB) stars in the Milky Way's halo, drawn from SDSS DR8. We search for position-velocity substructure in these data, a signature of the hierarchical assembly of the stellar halo. Using a cumulative "close pair distribution" as a statistic in the four-dimensional space of sky position, distance, and velocity, we quantify the presence of position-velocity substructure at high statistical significance among the BHB stars: pairs of BHB stars that are close in position on the sky tend to have more similar distances and radial velocities compared to a random sampling of these overall distributions. We make analogous mock observations of 11 numerical halo formation simulations, in which the stellar halo is entirely composed of disrupted satellite debris, and find a level of substructure comparable to that seen in the actually observed BHB star sample. This result quantitatively confirms the hierarchical build-up of the stellar halo through a signature in phase (position-velocity) space. In detail, the structure present in the BHB stars is somewhat less prominent than that seen in most simulated halos, quite possibly because BHB stars represent an older sub-population. BHB stars located beyond 20kpc from the Galactic center exhibit stronger substructure than at r_gc_<20kpc.
- ID:
- ivo://CDS.VizieR/J/ApJ/794/60
- Title:
- SDSS RGB stars distances
- Short Name:
- J/ApJ/794/60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present distance determinations for a large and clean sample of red giant branch stars selected from the ninth data release of the Sloan Digital Sky Survey (Adelman-McCarthy et al. 2012ApJS..203...21A, Cat. V/139). The distances are calculated based on both observational cluster fiducials and theoretical isochrones. Distributions of distances from the two methods are very similar with peaks at about 10 kpc and tails extending to more than 70 kpc. We find that distances from the two methods agree well for the majority of the sample stars; though, on average, distances based on isochrones are 10% higher than those based on fiducials. We test the accuracy of our distance determinations using 332 stars from 10 Galactic globular and open clusters. The average relative deviation from the literature cluster distances is 4% for the fiducial-based distances and 8% for the isochrone-based distances, both of which are within the uncertainties. We find that the effective temperature and surface gravity derived from low-resolution spectra are not accurate enough to essentially improve the performance of distance determinations. However, for stars with significant extinction, effective temperature may help to better constrain their distances to some extent. We make our sample stars and their distances available from an online catalog. The catalog comprises 17941 stars with reasonable distance estimations reaching to more than 70 kpc, which is suitable for the investigation of the formation and evolution of the Galaxy, especially the Galactic halo.
- ID:
- ivo://CDS.VizieR/J/A+A/597/A30
- Title:
- Seismology and spectroscopy of CoRoGEE red giants
- Short Name:
- J/A+A/597/A30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the CoRoGEE dataset -- obtained from CoRoT lightcurves for 606 red giant stars in two fields of the Galactic disc which have been co-observed for an ancillary project of the Apache Point Observatory Galactic Evolution Experiment (APOGEE). The CoRoGEE stars cover a large radial range of the Milky Way's disc (5kpc<RGal<14kpc) and thus provide a valuable dataset for Galactic Archaeology studies. We have used the Bayesian parameter estimation code PARAM to calculate distances, extinctions, masses, and ages for these stars in a homogeneous analysis, resulting in relative statistical uncertainties of 2% in distance, 4% in radius, ~9% in mass and ~25% in age. We also assess systematic age uncertainties due to different input physics and mass loss.
- ID:
- ivo://CDS.VizieR/J/MNRAS/460/1131
- Title:
- Selection function of Milky Way field stars
- Short Name:
- J/MNRAS/460/1131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Gaia-ESO Survey was designed to target all major Galactic components (i.e. bulge, thin and thick discs, halo and clusters), with the goal of constraining the chemical and dynamical evolution of the Milky Way. This paper presents the methodology and considerations that drive the selection of the targeted, allocated and successfully observed Milky Way field stars. The detailed understanding of the survey construction, specifically the influence of target selection criteria on observed Milky Way field stars is required in order to analyse and interpret the survey data correctly. We present the target selection process for the Milky Way field stars observed with Very Large Telescope/Fibre Large Array Multi Element Spectrograph and provide the weights that characterize the survey target selection. The weights can be used to account for the selection effects in the Gaia-ESO Survey data for scientific studies. We provide a couple of simple examples to highlight the necessity of including such information in studies of the stellar populations in the Milky Way.
- ID:
- ivo://CDS.VizieR/J/other/Sci/348.413
- Title:
- Sgr A East SNR multiwavelength images
- Short Name:
- J/other/Sci/348.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Dust formation in supernova ejecta is currently the leading candidate to explain the large quantities of dust observed in the distant, early universe. However, it is unclear whether the ejecta-formed dust can survive the hot interior of the supernova remnant (SNR). We present infrared observations of ~0.02 solar masses of warm (~100 kelvin) dust seen near the center of the ~10,000-year-old Sagittarius A East SNR at the Galactic center. Our findings indicate the detection of dust within an older SNR that is expanding into a relatively dense surrounding medium (electron density ~10^3^ centimeters^-3^) and has survived the passage of the reverse shock. The results suggest that supernovae may be the dominant dust-production mechanism in the dense environment of galaxies of the early universe.
- ID:
- ivo://CDS.VizieR/J/AJ/153/57
- Title:
- Shape parameters for 154 Galactic open clusters
- Short Name:
- J/AJ/153/57
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the Galactic characteristics of 154 open clusters using the stellar statistics method with data from the WEBDA database. We find that all clusters in our sample are elongated in shape, which indicates that the spherical clusters are stretched out to be ellipsoid as a function of age (log(age/year)=6.64{--}9.7). By dividing a cluster into a central core and an outer part, we have computed the apparent ellipticities of these two parts respectively. The scale relations between ellipticities and age indicate that the outer parts of open clusters become more elliptical while the central cores remain circular. We suppose that the outer parts become more elliptical because they are more subjected to the external forces, e.g., Galactic differential rotation, while the central cores form a circular shape under the domination of stellar dynamics. We have also performed an analysis of the crucial influence of cluster mass and location on its shape.
- ID:
- ivo://CDS.VizieR/J/MNRAS/454/507
- Title:
- Short-period var. stars OmegaWhite survey
- Short Name:
- J/MNRAS/454/507
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the goals, strategy and first results of the OmegaWhite survey: a wide-field high-cadence g-band synoptic survey which aims to unveil the Galactic population of short-period variable stars (with periods <80min), including ultracompact binary star systems and stellar pulsators. The ultimate goal of OmegaWhite is to cover 400deg^2^ along the Galactic plane reaching a depth of g=21.5mag (10{sigma}), using OmegaCam on the VLT Survey Telescope (VST). The fields are selected to overlap with surveys such as the Galactic Bulge Survey and the VST Photometric H{alpha} Survey of the Southern Galactic Plane for multiband colour information. Each field is observed using 38 exposures of 39s each, with a median cadence of ~2.7min for a total duration of two hours. Within an initial 26deg^2^, we have extracted the light curves of 1.6 million stars, and have identified 613 variable candidates which satisfy our selection criteria. Furthermore, we present the light curves and statistical properties of 20 sources which have the highest likelihood of being variable stars. One of these candidates exhibits the colours and light-curve properties typically associated with ultracompact AM CVn binaries, although its spectrum exhibits weak Balmer absorption lines and is thus not likely to be such a binary system. We also present follow-up spectroscopy of five other variable candidates, which identifies them as likely low-amplitude {delta} Sct pulsating stars.
- ID:
- ivo://CDS.VizieR/J/AJ/151/143
- Title:
- Silicon depletion in the interstellar medium
- Short Name:
- J/AJ/151/143
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report interstellar silicon (Si) depletion and dust-phase column densities of Si along 131 Galactic sight lines using archival observations. The data were corrected for differences in the assumed oscillator strength. This is a much larger sample than previous studies but confirms the majority of results, which state that the depletion of Si is correlated with the average density of hydrogen along the line of sight (<n(H)>) as well as the fraction of hydrogen in molecular form (f(H_2_)). We also find that the linear part of the extinction curve is independent of Si depletion. Si depletion is correlated with the bump strength (c_3_/R_V_) and the FUV curvature (c_4_/R_V_) suggesting that silicon plays a significant role in both the 2175{AA} bump and the FUV rise.
