- ID:
- ivo://CDS.VizieR/J/AJ/144/49
- Title:
- Quasars from SDSS-DR7, WISE and UKIDSS surveys
- Short Name:
- J/AJ/144/49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of 37842 quasars in the Sloan Digital Sky Survey (SDSS) Data Release 7, which have counterparts within 6" in the Wide-field Infrared Survey Explorer (WISE) Preliminary Data Release. The overall WISE detection rate of the SDSS quasars is 86.7%, and it decreases to less than 50.0% when the quasar magnitude is fainter than i=20.5. We derive the median color-redshift relations based on this SDSS-WISE quasar sample and apply them to estimate the photometric redshifts of the SDSS-WISE quasars. We find that by adding the WISE W1- and W2-band data to the SDSS photometry we can increase the photometric redshift reliability, defined as the percentage of sources with photometric and spectroscopic redshift difference less than 0.2, from 70.3% to 77.2%. We also obtain the samples of WISE-detected normal and late-type stars with SDSS spectroscopy, and present a criterion in the z-W1 versus g-z color-color diagram, z-W1>0.66(g-z)+2.01, to separate quasars from stars. With this criterion we can recover 98.6% of 3089 radio-detected SDSS-WISE quasars with redshifts less than four and overcome the difficulty in selecting quasars with redshifts between 2.2 and 3 from SDSS photometric data alone. We also suggest another criterion involving the WISE color only, W1-W2>0.57, to efficiently separate quasars with redshifts less than 3.2 from stars. In addition, we compile a catalog of 5614 SDSS quasars detected by both WISE and UKIDSS surveys and present their color-redshift relations in the optical and infrared bands. By using the SDSS ugriz, UKIDSS, YJHK, and WISE W1- and W2-band photometric data, we can efficiently select quasar candidates and increase the photometric redshift reliability up to 87.0%. We discuss the implications of our results on the future quasar surveys. An updated SDSS-WISE quasar catalog consisting of 101853 quasars with the recently released WISE all-sky data is also provided.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/132/2665
- Title:
- QUEST2 BRI photometry of Taurus-Auriga PMS
- Short Name:
- J/AJ/132/2665
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a drift-scan survey covering a ~5{deg}x5{deg} region toward the southern portion of the Taurus-Auriga molecular cloud. Data taken in the B,R,I filters with the Quest-2 camera on the Palomar 48 inch (1.2m) Samuel Oschin Telescope were combined with Two Micron All Sky Survey near-infrared photometry to select candidate young stars. Follow-up optical spectroscopy of 190 candidates led to the identification of 42 new low-mass pre-main-sequence stars with spectral types M4-M8, of which approximately half exhibit surface gravity signatures similar to known Taurus stars, while the other half exhibit surface gravity signatures similar to members of the somewhat older Upper Scorpius, TW Hya, and Pic associations.
- ID:
- ivo://CDS.VizieR/J/AJ/125/1537
- Title:
- QUIRC Chandra sources in OMC 2/3
- Short Name:
- J/AJ/125/1537
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We conducted deep near-infrared (NIR) imaging observations of Orion molecular clouds 2 and 3 using the Quick Infrared Camera on the 88 inch (2.2m) telescope of the University of Hawaii. Our purposes were (1) to generate a comprehensive NIR source catalog of these star-forming clouds and (2) to identify the NIR counterpart of the Chandra X-ray sources that have no counterpart in the Two Micron All Sky Survey (2MASS) catalog. Our J-, H-, and K-band observations are ~2mag deeper than those of 2MASS and match the current Chandra observation well. We detected 1448 NIR sources, for which we derived the position, the J-, H-, and K-band magnitude, and the 2MASS counterpart. Using this catalog, we identified the NIR counterpart for ~42% of the 2MASS unidentified Chandra sources. The nature of these Chandra sources are discussed using their NIR colors and spatial distributions, and a dozen protostar and brown dwarf candidates are identified.
- ID:
- ivo://CDS.VizieR/J/ApJ/703/1569
- Title:
- Radial distribution in SINGS galaxies. I.
- Short Name:
- J/ApJ/703/1569
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present ultraviolet through far-infrared (FIR) surface brightness profiles for the 75 galaxies in the Spitzer Infrared Nearby Galaxies Survey (SINGS). The imagery used to measure the profiles includes Galaxy Evolution Explorer UV data, optical images from Kitt Peak National Observatory, Cerro Tololo Inter-American Observatory, and Sloan Digital Sky Survey, near-IR data from Two Micron All Sky Survey, and mid- and FIR images from Spitzer. Along with the radial profiles, we also provide multi-wavelength asymptotic magnitudes and several nonparametric indicators of galaxy morphology: the concentration index (C42), the asymmetry (A), the Gini coefficient (G), and the normalized second-order moment of the brightest 20% of the galaxy's flux ({overline}M_20_). In this paper, the first of a series, we describe the technical aspects regarding the surface photometry, and present a basic analysis of the global and structural properties of the SINGS galaxies at different wavelengths.
- ID:
- ivo://CDS.VizieR/J/ApJ/835/251
- Title:
- Radial velocities and BVIc LCs of the EB* CU Cnc
- Short Name:
- J/ApJ/835/251
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spectral features, radial velocities, elemental abundance estimates, other spectral data, and BVI_C_ light curves are reported for the double-M dwarf eclipsing binary CU Cancri-a good target for a radius check versus the Zero Age Main Sequence (ZAMS) due to the low component masses and corresponding very slow evolutionary expansion. The estimate of [Fe/H] is about 0.4, although continuum placement and other difficulties due to line crowding introduce the usual uncertainties for red dwarfs. Detection of the LiI{lambda}6707 line was attempted, with an estimated upper limit of 50m{AA}. Spectral and photometric indicators of stellar activity are described and illustrated. Other objectives were to measure the stellar radii via simultaneous velocity and light-curve solutions of earlier and new data while also improving the ephemeris by filling gaps in timewise coverage with the new velocities and eclipse data from the new light curves. The radii from our solutions agree within about 2% with those from Ribas, being slightly larger than expected for most estimates of the ZAMS. Some aspects of the red dwarf radius anomaly are briefly discussed. Evolution tracks show only very slight age-related expansion for masses near those in CU Cnc. Such expansion could be significant if CU Cnc were similar in age to the Galaxy, but then its Galactic velocity components should be representative of Population II, and they are not.
- ID:
- ivo://CDS.VizieR/J/ApJ/751/6
- Title:
- Radial velocities in {omega} Cen
- Short Name:
- J/ApJ/751/6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The multi-object fiber-fed spectrograph AAOmega at the Anglo-Australian Telescope has been used to establish and measure accurate (<=1km/s) radial velocities for a new sample of members in the outer parts of the stellar system {omega} Centauri. The new sample more than doubles the number of known members with precise velocities that lie between 25' and 45' from the cluster center. Combining this sample with earlier work confirms that the line-of-sight velocity dispersion of {omega} Cen remains approximately constant at ~6.5km/s in the outer parts of the cluster, which contain only a small fraction of the total cluster stellar mass. It is argued that the approximately constant velocity dispersion in the outer regions is most likely a consequence of external influences, such as the tidal shock heating that occurs each time {omega} Cen crosses the Galactic plane. There is therefore no requirement to invoke dark matter or non-standard gravitational theories.
- ID:
- ivo://CDS.VizieR/J/A+A/473/143
- Title:
- Radial velocities of C stars near Galactic plane
- Short Name:
- J/A+A/473/143
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The availability, from 2MASS, of a large homogeneous sample of Galactic C stars and the recognition that their absolute magnitude can be accurately determined offer the possibility to use them as kinematical probes to investigate motions in the thin or thick disks. Our aims is to determine the radial velocities for 70 C stars, a few degrees from the Galactic plane and distributed in longitudes from 60{deg} to 220{deg}.
- ID:
- ivo://CDS.VizieR/J/ApJ/798/23
- Title:
- Radial velocities of giant stars in NGC 6388
- Short Name:
- J/ApJ/798/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new radial velocity measurements for 82 stars, members of the Galactic globular cluster (GC) NGC 6388, obtained from ESO-VLT K-band Multi Object Spectrograph (KMOS) spectra acquired during the instrument Science Verification. The accuracy of the wavelength calibration is discussed and a number of tests of the KMOS response are presented. The cluster systemic velocity obtained (81.3+/-1.5km/s) is in very good agreement with previous determinations. While a hint of ordered rotation is found between 9" and 20" from the cluster center, where the distribution of radial velocities is clearly bimodal, more data are needed before drawing any firm conclusions. The acquired sample of radial velocities has also been used to determine the cluster velocity dispersion (VD) profile between ~9" and 70", supplementing previous measurements at r<2" and r>60" obtained with ESO-SINFONI and ESO-FLAMES spectroscopy, respectively. The new portion of the VD profile nicely matches the previous ones, better defining the knee of the distribution. The present work clearly shows the effectiveness of a deployable integral field unit in measuring the radial velocities of individual stars for determining the VD profile of Galactic GCs. It represents the pilot project for an ongoing large program with KMOS and FLAMES at the ESO-VLT, aimed at determining the next generation of VD and rotation profiles for a representative sample of GCs.
- ID:
- ivo://CDS.VizieR/J/ApJ/730/67
- Title:
- Radial velocities of low-mass white dwarfs
- Short Name:
- J/ApJ/730/67
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe spectroscopic observations of 21 low-mass (<=0.45M_{sun}_) white dwarfs (WDs) from the Palomar-Green survey obtained over four years. We use both radial velocities and infrared photometry to identify binary systems, and find that the fraction of single, low-mass WDs is <=30%. We discuss the potential formation channels for these single stars including binary mergers of lower-mass objects. However, binary mergers are not likely to explain the observed number of single low-mass WDs. Thus, additional formation channels, such as enhanced mass loss due to winds or interactions with substellar companions, are likely.
- ID:
- ivo://CDS.VizieR/J/AJ/136/506
- Title:
- Radial velocities of {omega} Centauri members
- Short Name:
- J/AJ/136/506
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used the two-degree field (2dF) multi-fiber spectrograph of the Anglo-Australian Telescope (AAT) to search for candidate members of the unusual globular cluster omega Centauri at and beyond the cluster tidal radius. Velocities with an accuracy of ~10km/s were obtained for 4105 stars selected to lie in the vicinity of the lower giant branch in the cluster color-magnitude diagram (CMD) and which cover an area on the sky of ~2.4x3.9{deg}^2^ centered on the cluster.
