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- ID:
- ivo://CDS.VizieR/J/ApJS/227/18
- Title:
- Candidate stellar bowshock nebulae from MIR
- Short Name:
- J/ApJS/227/18
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We identify 709 arc-shaped mid-infrared nebula in 24um Spitzer Space Telescope or 22um Wide Field Infrared Explorer surveys of the Galactic Plane as probable dusty interstellar bowshocks powered by early-type stars. About 20% are visible at 8um or at shorter mid-infrared wavelengths. The vast majority (660) have no previous identification in the literature. These extended infrared sources are strongly concentrated near the Galactic mid-plane, with an angular scale height of ~0.6{deg}. All host a symmetrically placed star implicated as the source of a stellar wind sweeping up interstellar material. These are candidate "runaway" stars potentially having high velocities in the reference frame of the local medium. Among the 286 objects with measured proper motions, we find an unambiguous excess with velocity vectors aligned with the infrared morphology-kinematic evidence that many of these are "runaway" stars with large peculiar motions responsible for the bowshock signature. We discuss a population of "in situ" bowshocks (~103 objects) that face giant HII regions where the relative motions between the star and ISM may be caused by bulk outflows from an overpressured bubble. We also identify ~58 objects that face 8um bright-rimmed clouds and apparently constitute a sub-class of in situ bowshocks where the stellar wind interacts with a photoevaporative flow (PEF) from an eroding molecular cloud interface (i.e., "PEF bowshocks"). Orientations of the acurate nebulae exhibit a correlation over small angular scales, indicating that external influences such as HII regions are responsible for producing some bowshock nebulae. However, the vast majority of the nebulae in this sample appear to be isolated (499 objects) from obvious external influence
- ID:
- ivo://CDS.VizieR/J/ApJS/232/15
- Title:
- Candidate strong lens systems from DES obs.
- Short Name:
- J/ApJS/232/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of searches for strong gravitational lens systems in the Dark Energy Survey (DES) Science Verification and Year1 observations. The Science Verification data span approximately 250{deg}^2^ with a median i-band limiting magnitude for extended objects (10{sigma}) of 23.0. The Year 1 data span approximately 2000{deg}^2^ and have an i-band limiting magnitude for extended objects (10{sigma}) of 22.9. As these data sets are both wide and deep, they are particularly useful for identifying strong gravitational lens candidates. Potential strong gravitational lens candidate systems were initially identified based on a color and magnitude selection in the DES object catalogs or because the system is at the location of a previously identified galaxy cluster. Cutout images of potential candidates were then visually scanned using an object viewer and numerically ranked according to whether or not we judged them to be likely strong gravitational lens systems. Having scanned nearly 400000 cutouts, we present 374 candidate strong lens systems, of which 348 are identified for the first time. We provide the R.A. and decl., the magnitudes and photometric properties of the lens and source objects, and the distance (radius) of the source(s) from the lens center for each system.
- ID:
- ivo://CDS.VizieR/J/MNRAS/413/1581
- Title:
- Candidate subdwarfs and white dwarfs
- Short Name:
- J/MNRAS/413/1581
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photometry from the Two-Micron All-Sky Survey (2MASS), United States Naval Observatory CCD Astrograph Catalog (UCAC3) and SuperCosmos catalogues, together with proper motions from the Tycho-2, Kharkiv Proper Motions (XPM) and UCAC3 catalogues, is used to select all-sky samples of 28 candidate white dwarfs, 1826 evolved and 7641 unevolved subdwarfs for R from 9-17mag. The samples are separated from main-sequence stars with an admixture of less than 10 per cent, owing to an analysis of the distribution of the stars in colour index versus reduced proper-motion diagrams for various latitudes using related Monte Carlo simulations. It is shown that the XPM and UCAC3 catalogues have the same level of proper-motion accuracy. Most of the selected stars have at least six-band photometry. This allows us to eliminate some admixtures and reveal some binaries. Empirical calibrations of absolute magnitude versus colour index and reduced proper motion for Hipparcos stars give us distances and a three-dimensional (3D) distribution for all the selected stars. It is shown that the subdwarf samples are almost complete for the Tycho-2 stars, i.e. to 11mag or 150pc from the Sun. For fainter stars from the XPM and UCAC3 catalogues, the subdwarf samples are complete only to 20-60 per cent because of the selection method and incompleteness of the catalogues.
- ID:
- ivo://CDS.VizieR/J/MNRAS/435/3306
- Title:
- Candidate type II QSOs in SDSS III
- Short Name:
- J/MNRAS/435/3306
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- At low redshifts, dust-obscured quasars often have strong yet narrow permitted lines in the rest-frame optical and ultraviolet, excited by the central active nucleus, earning the designation type II quasars. We present a sample of 145 candidate type II quasars at redshifts between 2 and 4.3, encompassing the epoch at which quasar activity peaked in the universe. These objects, selected from the quasar sample of the Baryon Oscillation Spectroscopic Survey of the Sloan Digital Sky Survey III, are characterized by weak continuum in the rest-frame ultraviolet (typical continuum magnitude of i~22) and strong lines of CIV and Ly{alpha}, with full width at half-maximum less than 2000km/s. The continuum magnitudes correspond to an absolute magnitude of -23 or brighter at redshift 3, too bright to be due exclusively to the host galaxies of these objects. Roughly one third of the objects are detected in the shorter wavelength bands of the Wide-Field Infrared Survey Explorer survey; the spectral energy distributions of these objects appear to be intermediate between classic type I and type II quasars seen at lower redshift. Five objects are detected at rest frame 6{mu}m by Spitzer, implying bolometric luminosities of several times 10^46^erg/s. We have obtained polarization measurements for two objects; they are roughly 3 percent polarized. We suggest that these objects are luminous quasars, with modest dust extinction (A_V_~0.5mag), whose ultraviolet continuum also includes a substantial scattering contribution. Alternatively, the line of sight to the central engines of these objects may be obscured by optically thick material whose covering fraction is less than unity.
- ID:
- ivo://CDS.VizieR/J/ApJS/194/6
- Title:
- Candidate X-ray emitting OB stars in Carina
- Short Name:
- J/ApJS/194/6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of a new survey of massive, OB stars throughout the Carina Nebula using the X-ray point source catalog provided by the Chandra Carina Complex Project (CCCP) in conjunction with infrared (IR) photometry from the Two Micron All-Sky Survey and the Spitzer Space Telescope Vela-Carina survey. Mid-IR photometry is relatively unaffected by extinction, hence it provides strong constraints on the luminosities of OB stars, assuming that their association with the Carina Nebula, and hence their distance, is confirmed. We fit model stellar atmospheres to the optical (UBV) and IR spectral energy distributions (SEDs) of 182 OB stars with known spectral types and measure the bolometric luminosity and extinction for each star. Using X-ray emission as a strong indicator of association with Carina, we identify 94 candidate OB stars with L_bol_>~10^4^L_{sun}_ by fitting their IR SEDs. If the candidate OB stars are eventually confirmed by follow-up spectroscopic observations, the number of cataloged OB stars in the Carina Nebula will increase by ~50%.
- ID:
- ivo://CDS.VizieR/J/ApJ/838/61
- Title:
- Candidate X-ray OB stars in MYStIX regions
- Short Name:
- J/ApJ/838/61
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Massive O-type and early B-type (OB) stars in the nearby Galaxy remain incompletely cataloged due to high extinction, bright visible and infrared nebular emission in H II regions, and high field star contamination. These difficulties are alleviated by restricting the search to stars with X-ray emission. Using the X-ray point sources from the Massive Young Star-forming Complex Study in Infrared and X-Rays (MYStIX) survey of OB-dominated regions, we identify 98 MYStIX candidate OB (MOBc) stars by fitting their 1-8{mu}m spectral energy distributions (SEDs) with reddened stellar atmosphere models. We identify 27 additional MOBc stars based on JHK_S_ photometry of X-ray stars lacking SED fitting. These candidate OB stars indicate that the current census of stars earlier than B1, taken across the 18 MYStIX regions studied, is less than 50% complete. We also fit the SEDs of 239 previously published OB stars to measure interstellar extinction and bolometric luminosities, revealing six candidate massive binary systems and five candidate O-type (super)giants. As expected, candidate OB stars have systematically higher extinction than previously published OB stars. Notable results for individual regions include identification of the OB population of a recently discovered massive cluster in NGC 6357, an older OB association in the M17 complex, and new massive luminous O stars near the Trifid Nebula. In several relatively poorly studied regions (RCW 38, NGC 6334, NGC 6357, Trifid, and NGC 3576), the OB populations may increase by factors of 2.
- ID:
- ivo://CDS.VizieR/J/AJ/158/235
- Title:
- Candidate X-ray sources in IRAS 09002-4732 region
- Short Name:
- J/AJ/158/235
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- IRAS 09002-4732 is a poorly studied embedded cluster of stars in the Vela Molecular Ridge at a distance of 1.7 kpc. Deep observations with the Chandra X-ray Observatory, combined with existing optical and infrared surveys, produce a catalog of 441 probable pre-main-sequence members of the region. The stellar spatial distribution has two components: most stars reside in a rich, compact, elliptical cluster, but a minority reside within a molecular filament several parsecs long that straddles the cluster. The filament has active distributed star formation with dozens of unclustered protostars. The cluster pre-main-sequence population is =<0.8 Myr old and deeply embedded; its most massive member is extremely young, producing an ultracompact H II region. The cluster total population deduced from the X-ray luminosity function is surprisingly rich, twice that of the Orion Nebula Cluster. The cluster core is remarkably dense where strong N-body interactions should be occurring; its initial mass function may be deficient in massive stars. We infer that IRAS 09002-4732 is a rare case where a rich cluster is forming today in a molecular filament, consistent with astrophysical models of cluster formation in clouds that involve the hierarchical formation and merging of groups in molecular filaments.
- ID:
- ivo://CDS.VizieR/J/ApJ/822/49
- Title:
- Candidate YSOs in AFGL 333 with NEWFIRM & Spitzer
- Short Name:
- J/ApJ/822/49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- One of the key questions in the field of star formation is the role of stellar feedback on the subsequent star formation process. The W3 giant molecular cloud complex at the western border of the W4 super bubble is thought to be influenced by the massive stars in W4. This paper presents a study of the star formation activity within AFGL 333, a ~10^4^M_{sun}_ cloud within W3, using deep JHKs photometry obtained from the NOAO Extremely Wide Field Infrared Imager combined with Spitzer IRAC and MIPS photometry. Based on the infrared excess, we identify 812 candidate young stellar objects (YSOs) in the complex, of which 99 are Class I and 713 are Class II sources. The stellar density analysis of YSOs reveals three major stellar aggregates within AFGL333, namely AFGL 333 Main, AFGL 333 NW1 and AFGL 333 NW2. The disk fraction within AFGL 333 is estimated to be ~50%-60%. We use the extinction map made from the H-K_s_ colors of the background stars and CO data to understand the cloud structure and to estimate the cloud mass. From the stellar and cloud mass associated with AFGL 333, we infer that the region is currently forming stars with an efficiency of ~4.5% and at a rate of ~2-3M_{sun}_/Myr/pc^2^. In general, the star formation activity within AFGL 333 is comparable to that of nearby low mass star-forming regions. We do not find any strong evidence to suggest that the stellar feedback from the massive stars of nearby W4 super bubble has affected the global star formation properties of the AFGL 333 region.
- ID:
- ivo://CDS.VizieR/J/AJ/130/1177
- Title:
- C and N abundances for M15 stars
- Short Name:
- J/AJ/130/1177
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of a large sample of moderate-resolution Keck Low Resolution Imaging Spectrometer spectra of subgiants and stars at the base of the red giant branch (RGB) in the Galactic globular cluster (GC) M15 (NGC 7078), most within the range 16.5<V<19.5 (1.2<M_V_<4.2), with the goal of deriving C abundances (from the G band of CH) and N abundances (from the NH band at 3360{AA}).
