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- ID:
- ivo://CDS.VizieR/J/MNRAS/406/197
- Title:
- Ultra-steep spectrum radio sources in SDSS
- Short Name:
- J/MNRAS/406/197
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyse optical and radio properties of radio galaxies detected in the Sloan Digital Sky Survey. The sample of radio sources is selected from the catalogue of Kimball & Ivezic (2008AJ....136..684K) with flux densities at 325, 1400 and 4850MHz, using Westerbork Northern Sky Survey, NRAO VLA Sky Survey and Green Bank 6cm radio surveys and from flux measurements at 74MHz taken from Very Large Array Low-Frequency Sky Survey (Cohen et al. 2006, Cat. VIII/79). We study radio galaxy spectral properties using radio colour-colour diagrams and find that our sample follows a single power law from 74 to 4850MHz.
14833. Ultraviolet Excess Galaxies
- ID:
- ivo://CDS.VizieR/VII/63
- Title:
- Ultraviolet Excess Galaxies
- Short Name:
- VII/63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog contains a list of 412 faint galaxies selected for their apparent ultraviolet excess. The galaxies were selected from a 3-color (UBV) plate taken with the Palomar 48-inch Schmidt telescope. The 14-inch-square plates cover an area of 30 square degrees centered on Kapteyn Selected Area 28. The catalog includes running numbers, coordinates, color codes, magnitude codes, morphologies, diameters, and notes. The catalogued galaxies were selected by eye from the Palomar Schmidt 3-color (UBV) plate PS24771, centered on Kapteyn Selexted Area 28 and taken by Usher under conditions of good seeing and transparency.
- ID:
- ivo://CDS.VizieR/J/ApJ/861/153
- Title:
- Ultraviolet Extinction in the GALEX Bands. UVEXT
- Short Name:
- J/ApJ/861/153
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Interstellar extinction in ultraviolet is the most severe in comparison with optical and infrared wavebands and a precise determination plays an important role in correctly recovering the ultraviolet brightness and colors of objects. By finding the observed bluest colors at the given effective temperature and metallicity range of dwarf stars, stellar intrinsic colors, C_B,V_^0^, C_NUV,B_^0^, C_FUV,B_^0^, and C_FUV,NUV_^0^, are derived according to the stellar parameters from the LAMOST spectroscopic survey and photometric results from the GALEX and APASS surveys. With the derived intrinsic colors, the ultraviolet color excesses are calculated for about 25,000 A- and F-type dwarf stars. Analysis of the color excess ratios yields the extinction law related to the GALEX UV bands: E_NUV,B_/E_B,V_=3.77, E_FUV,B_/E_B,V_=3.39, and E_FUV,NUV_/E_B,V_=-0.38. The results agree very well with previous works in the NUV band and in general with the extinction curve derived by Fitzpatrick (1999PASP..111...63F) for R_V_=3.35.
14835. Ultraviolet P Cygni profiles
- ID:
- ivo://CDS.VizieR/J/ApJS/95/163
- Title:
- Ultraviolet P Cygni profiles
- Short Name:
- J/ApJS/95/163
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have selected spectra of 232 stars from the IUE archives for inclusion in an atlas intended for various uses but tailored especially for the study of stellar winds. The atlas covers the range in spectral types from O3 to F8. The full atlas covers the reduced and normalized high resolution spectra from the IUE long- and short-wavelength spectrographs. Here we discuss the selection of the stars and the data reduction, and we present in velocity units the profiles of lines formed in the stellar winds. The selected lines cover a wide range of ionizations, allowing a comparison of the profiles from different ions in the wind of each star and a comparison of the different wind lines as a function of spectral type and luminosity. We also present the basic data on the program stars to facilitate study of the dependence of wind features on stellar parameters such as luminosity, temperature, escape velocity, and v sin i. We provide an overview of the characteristic behavior of the wind lines in the H-R diagram. The complete spectra are available in digital form through the NASA Astrophysics Data System (ADS). We offer a description of the electronic database that is available through the ADS and guidelines for obtaining access to that database.
- ID:
- ivo://CDS.VizieR/J/AJ/137/3761
- Title:
- Ultraviolet quasi-stellar objects
- Short Name:
- J/AJ/137/3761
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a sample of spectroscopically confirmed quasi-stellar objects (QSOs) with FUV-NUV color (as measured by Galaxy Evolution Explorer (GALEX) photometry, FUV band: 1344-1786{AA}, NUV band: 1771-2831{AA}) bluer than canonical QSO templates and than the majority of known QSOs. We analyze their FUV to NIR colors, luminosities, and optical spectra. The sample includes a group of 150 objects at low redshift (z<0.5), and a group of 21 objects with redshift 1.7<z<2.6.
- ID:
- ivo://CDS.VizieR/J/ApJS/247/47
- Title:
- Ultraviolet survey of M31 with UVIT on AstroSat
- Short Name:
- J/ApJS/247/47
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An ultraviolet survey of M31 has been carried out during 2017-19 with the UltraViolet Imaging Telescope (UVIT) instrument on board the AstroSat Observatory. Here we analyze far- and near-ultraviolet (FUV and NUV) observations from the M31 UVIT survey, which covers a sky area of ~3{deg}x1{deg} with spatial resolution of ~1". The observations included six filter bands in the wavelength range of 120-280nm. The limiting magnitude (AB) in the FUV band (CaF2 filter), which has the largest number of detected sources, is ~23. The primary product of this work is the M31 UVIT point-source catalog containing positions and photometry. In total ~75000 sources were detected at FUV or NUV wavelengths.
- ID:
- ivo://CDS.VizieR/J/A+A/544/A156
- Title:
- UltraVISTA Catalogue Release DR1
- Short Name:
- J/A+A/544/A156
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we describe the first data release of the UltraVISTA near-infrared imaging survey of the COSMOS field. We summarise the key goals and design of the survey and provide a detailed description of our data reduction techniques. We provide stacked, sky-subtracted images in Y JHKs and narrow-band filters constructed from data collected during the first year of UltraVISTA observations.
- ID:
- ivo://CDS.VizieR/J/MNRAS/446/470
- Title:
- ULX candidates in luminous infrared galaxies
- Short Name:
- J/MNRAS/446/470
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from a Chandra study of ultraluminous X-ray sources (ULXs) in a sample of 17 nearby (D_L_<60Mpc) luminous infrared galaxies (LIRGs), selected to have star formation rates (SFRs) in excess of 7M_{sun}_/yr and low foreground Galactic column densities (N_H_<~5x10^20^cm^-2^). A total of 53 ULXs were detected and we confirm that this is a complete catalogue of ULXs for the LIRG sample. We examine the evolution of ULX spectra with luminosity in these galaxies by stacking the spectra of individual objects in three luminosity bins, finding a distinct change in spectral index at luminosity ~2x10^39^erg/s. This may be a change in spectrum as 10M_{sun}_ black holes transit from an ~ Eddington to a super-Eddington accretion regime, and is supported by a plausible detection of partially ionized absorption imprinted on the spectrum of the luminous ULX (L_X_~5x10^39^erg/s) CXOU J024238.9-000055 in NGC 1068, consistent with the highly ionized massive wind that we would expect to see driven by a super-Eddington accretion flow. This sample shows a large deficit in the number of ULXs detected per unit SFR (0.2 versus 2 ULXs, per M_{sun}_/yr) compared to the detection rate in nearby (D_L_<14.5Mpc) normal star-forming galaxies. This deficit also manifests itself as a lower differential X-ray luminosity function normalization for the LIRG sample than for samples of other star-forming galaxies. We show that it is unlikely that this deficit is a purely observational effect. Part of this deficit might be attributable to the high metallicity of the LIRGs impeding the production efficiency of ULXs and/or a lag between the star formation starting and the production of ULXs; however, we argue that the evidence - including very low N_ULX_/L_FIR_, and an even lower ULX incidence in the central regions of the LIRGs - shows that the main culprit for this deficit is likely to be the high column of gas and dust in these galaxies, that fuels the high SFR but also acts to obscure many ULXs from our view.
- ID:
- ivo://CDS.VizieR/J/AJ/143/144
- Title:
- ULX candidates in nearby Arp galaxies
- Short Name:
- J/AJ/143/144
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have conducted a statistical analysis of the ultra-luminous X-ray point sources (ULXs; L_X_>=10^39^erg/s) in a sample of galaxies selected from the Arp Atlas of Peculiar Galaxies (1996, Cat. VII/192; Webb, 1996, Cat. VII/192). We find a possible enhancement of a factor of ~2-4 in the number of ULXs per blue luminosity for the strongly interacting subset. Such an enhancement would be expected if ULX production is related to star formation, as interacting galaxies tend to have enhanced star formation rates on average. For most of the Arp galaxies in our sample, the total number of ULXs compared to the far-infrared luminosity is consistent with values found earlier for spiral galaxies. This suggests that for these galaxies, ULXs trace recent star formation. However, for the most infrared-luminous galaxies, we find a deficiency of ULXs compared to the infrared luminosity. For these very infrared-luminous galaxies, active galactic nuclei may contribute to powering the far-infrared; alternatively, ULXs may be highly obscured in the X-ray in these galaxies and therefore not detected by these Chandra observations. We determined local UV/optical colors within the galaxies in the vicinity of the candidate ULXs using Galaxy Evolution Explorer UV and Sloan Digitized Sky Survey optical images. In most cases, the distributions of colors are similar to the global colors of interacting galaxies. However, the u-g and r-i colors at the ULX locations tend to be bluer on average than these global colors, suggesting that ULXs are preferentially found in regions with young stellar populations. In the Arp sample there is a possible enhancement of a factor of ~2-5 in the fraction of galactic nuclei that are X-ray-bright compared to more normal spirals.
