- ID:
- ivo://CDS.VizieR/J/MNRAS/396/1231
- Title:
- Astrophotometric catalogue of NGC 891
- Short Name:
- J/MNRAS/396/1231
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep VI images obtained with the Advanced Camera for Surveys on board the Hubble Space Telescope, covering three fields in the north-east side of the edge-on disc galaxy NGC 891. The observed fields span a wide range of galactocentric distances along the eastern minor axis, extending from the plane of the disc to 12kpc, and out to ~25kpc along the major axis. The photometry of individual stars reaches ~2.5mag below the tip of the red giant branch. We use the astrophotometric catalogue to probe the stellar content and metallicity distribution across the thick disc and spheroid of NGC 891.
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- ID:
- ivo://CDS.VizieR/J/ApJS/250/23
- Title:
- AstroSat/UVIT and Chandra X-ray sources in M31
- Short Name:
- J/ApJS/250/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An ultraviolet (UV) survey of M31 has been carried out during 2017-19 with the Ultra-Violet Imaging Telescope (UVIT) instrument on board the AstroSat Observatory. Here we match the M31 UVIT source catalog with the Chandra source catalog. We find 67 UVIT/Chandra sources detected in a varying number of UV and X-ray bands. The UV and X-ray photometry is analyzed using power-law and blackbody models. The X-ray types include 15 low-mass X-ray binaries (LMXBs) and five active galactic nuclei. Crossmatches with catalogs of stars, clusters, and other source types yield the following: 20 of the UVIT/Chandra sources match with M31 globular clusters, and nine with foreground stars. Three more globular clusters and two more foreground stars are consistent with the UVIT source positions although outside the Chandra match radius of 1". The UV emission of the UVIT/Chandra sources associated with globular clusters is consistent with emission from blue horizontal branch stars rather than from the X-ray source. The LMXBs in globular clusters are among the most luminous globular clusters in M31. Comparison with stellar evolutionary tracks shows that the UVIT/Chandra sources with high UV blackbody temperatures are consistent with massive (10-30M_{sun}_) stars in M31.
- ID:
- ivo://CDS.VizieR/J/AJ/83/1549
- Title:
- A study of field galaxies. I.
- Short Name:
- J/AJ/83/1549
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As a first step towards a redetermination of the luminosity function and space distribution of field galaxies, we present data on a magnitude limited sample of galaxies in eight fields in the north and south galactic polar caps. Redshifts, accurate to about 100 km/s have been obtained for 164 of 184 galaxies brighter than J=15.0 (B~15.5) We have also measured magnitudes and colors for a large sample of 807 galaxies, complete to J~15.7.
- ID:
- ivo://CDS.VizieR/J/A+AS/31/439
- Title:
- A Survey of HII Regions in M31
- Short Name:
- J/A+AS/31/439
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An H-alpha survey, using a focal reducer and narrow-band interference filters, has resulted in the detection of nearly a thousand HII regions in M31. The catalog gives their positions, dimensions, and surface brightnesses. The surface brightnesses are on an absolute scale; the photographic measures were calibrated by using photoelectric measures from two different sources. The detection limit reached corresponds to an emission measure of 40cm^-6^pc at a temperature of 10000K.
- ID:
- ivo://CDS.VizieR/J/A+A/281/15
- Title:
- Asymmetries in radio source structures
- Short Name:
- J/A+A/281/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/A+A/445/465
- Title:
- ATCA 18.5 and 22GHz fluxes of Kuehr 5GHz sample
- Short Name:
- J/A+A/445/465
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We discuss our ATCA 18.5 and 22GHz flux density measurements of Southern extragalactic sources in the complete 5GHz sample of Kuehr et al. (1981, Cat. <VIII/5>). The high frequency (5-18.5GHz) spectral indices of steep-spectrum sources for which we have 18.5GHz data (66% of the complete sample) are systematically steeper than the low frequency (2.7-5GHz) ones, and there is evidence of an anti-correlation of high-frequency spectral index with luminosity. The completeness of 18.5GHz data is much higher (89%) for flat-spectrum sources (mostly quasars), which also exhibit a spectral steepening. Taking advantage of the almost complete redshift information on flat-spectrum quasars, we have estimated their 5GHz luminosity function in several redshift bins. The results confirm that their radio luminosity density peaks at z_peak about 2.5 but do not provide evidence for deviations from pure luminosity evolution as hinted at by other data sets. A comparison of our 22GHz flux densities with WMAP K-band data for flat-spectrum sources suggests that WMAP flux densities may be low by a median factor of about 1.2. The extrapolations of 5GHz counts and luminosity functions of flat-spectrum radio quasars using the observed distribution of the 5-18.5GHz spectral indices match those derived directly from WMAP data, indicating that the high frequency WMAP survey does not detect any large population of FSRQs with anomalous spectra.
- ID:
- ivo://CDS.VizieR/VIII/63
- Title:
- ATESP radio survey. II.
- Short Name:
- VIII/63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The ATESP survey is a radio survey accomplished with the Australia Telescope Compact Array (ATCA) at 1.4 GHz over a region of 26 square degrees centered at -40 and ranging in RA from 22h30m to 01h15m. The survey consists of 16 radio mosaics with 8x14 arcsec resolution and uniform sensitivity (1 sigma noise = 79 microJy). The final 6 sigmas catalogue contains 2960 sources down to a detection limit of 0.5 mJy. This region is superposed to the redshift survey ESO Slice Project (ESP) and is partly covered by the EIS survey (Patch A; see Cat. J/A+AS/130/323). Table 3 summarizes the main parameters for the final 16 mosaics: for each mosaic are listed the number of fields composing it (columns x rows), the tangent point (sky position used for geometry calculations) and the synthesized beam (size and position angle). The spatial resolution can vary from mosaic to mosaic depending on the particular array (6A, 6C or 6D) used in the observations. The mean value for the synthesized beam is 8"x14". The last three columns of Table 3 show the results of the noise analysis. For each mosaic we report the minimum (negative) flux (S_min) recorded on the image (typically |S_min| is of the order of 0.5 mJy, corresponding to the value at which we have stopped the cleaning) and the noise level. This has been evaluated either as the FWHM of the Gaussian fit to the flux distribution of the pixels (in the range +/-S_min), in order to check for correlated noise (sigma_fit), or as the standard deviation of the average flux in several source-free sub-regions of the mosaics, in order to verify uniformity (<sigma>).
- ID:
- ivo://CDS.VizieR/J/MNRAS/476/2717
- Title:
- AT20G-MWACS catalogue
- Short Name:
- J/MNRAS/476/2717
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new broad-band radio frequency catalogue across 0.12GHz<={nu}<=20GHz created by combining data from the Murchison Widefield Array Commissioning Survey, the Australia Telescope 20GHz survey, and the literature. Our catalogue consists of 1285 sources limited by S_20GHz_>40mJy at 5{sigma}, and contains flux density measurements (or estimates) and uncertainties at 0.074, 0.080, 0.119, 0.150, 0.180, 0.408, 0.843, 1.4, 4.8, 8.6, and 20GHz. We fit a second-order polynomial in log-log space to the spectral energy distributions of all these sources in order to characterize their broad-band emission. For the 994 sources that are well described by a linear or quadratic model we present a new diagnostic plot arranging sources by the linear and curvature terms. We demonstrate the advantages of such a plot over the traditional radio colour-colour diagram. We also present astrophysical descriptions of the sources found in each segment of this new parameter space and discuss the utility of these plots in the upcoming era of large area, deep, broad-band radio surveys.
- ID:
- ivo://CDS.VizieR/J/MNRAS/417/2651
- Title:
- AT20G-optical catalogue
- Short Name:
- J/MNRAS/417/2651
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Our current understanding of radio-loud active galactic nuclei (AGN) comes predominantly from studies at frequencies of 5GHz and below. With the recent completion of the Australia Telescope 20GHz (AT20G) survey, we can now gain insight into the high-frequency radio properties of AGN. This paper presents supplementary information on the AT20G sources in the form of optical counterparts and redshifts. Optical counterparts were identified using the SuperCOSMOS data base and redshifts were found from either the 6dF Galaxy Survey or the literature. We also report 144 new redshifts. For AT20G sources outside the Galactic plane, 78.5% have optical identifications and 30.9% have redshift information. The optical identification rate also increases with increasing flux density. Targets which had optical spectra available were examined to obtain a spectral classification.
- ID:
- ivo://CDS.VizieR/J/A+A/611/A28
- Title:
- ATLAS3D H{alpha} imaging of early-type galaxies
- Short Name:
- J/A+A/611/A28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The traditional knowledge of the mechanisms that caused the formation and evolution of early-type galaxies (ETG) in a hierarchical universe was challenged by the unexpected finding by ATLAS^3D^ that 86% of the ETGs show signs of a fast-rotating disk at their interior. This implies a common origin of most spiral galaxies, followed by a quenching phase, while only a minority of the most massive systems are slow rotators and were likely to be the products of merger events. Our aim is to improve our knowledge on the content and distribution of ionized hydrogen and their usage to form stars in a representative sample of ETGs for which the kinematics and detailed morphological classification were known from ATLAS^3D^. Methods. Using narrow-band filters centered on the redshifted H{alpha} line along with a broad-band (r-Gunn) filter to recover the stellar continuum, we observed or collected existing imaging observations for 147 ETGs (including members of the Virgo cluster) that are representative of the whole ATLAS3D survey. Fifty-five ETGs (37%) were detected in the H{alpha} line above our detection threshold, (EW(H{alpha})<=-1{AA}), and 21 harbor a strong source (EW(H{alpha})<=-5{AA}). The strong H{alpha} emitters appear associated with mostly low-mass (M*~10^10^M_{sun}_) S0 galaxies that contain conspicuous stellar and gaseous discs. These harbor significant star formation at their interior, including their nuclei. The weak H{alpha} emitters are almost one order of magnitude more massive, contain gas-poor discs and harbor an AGN at their centers. Their emissivity is dominated by [NII] and does not imply star formation. The 92 undetected ETGs constitute the majority in our sample and are gas-free systems that lack a disc and exhibit passive spectra even in their nuclei. These pieces of evidence reinforce the conclusion made previously that the evolution of ETGs followed the secular channel for the less massive systems and the dry merging channel for the most massive galaxies at the center of clusters of galaxies.
