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1172. Oph A mosaic image
- ID:
- ivo://CDS.VizieR/J/A+A/631/A58
- Title:
- Oph A mosaic image
- Short Name:
- J/A+A/631/A58
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observations of young stellar objects (YSOs) in centimeter bands can probe the continuum emission from growing dust grains, ionized winds, and magnetospheric activity, which are intimately connected to the evolution of protoplanetary disks and the formation of planets. We have carried out sensitive continuum observations toward the Ophiuchus A star-forming region using the Karl G. Jansky Very Large Array (VLA) at 10GHz over a field-of-view of 6' with a spatial resolution of {theta}_maj_x{theta}_min_~0.4"x0.2". We achieved a 5{mu}Jy/beam root-mean-square noise level at the center of our mosaic field of view. Among the eighteen sources we detected, sixteen are YSOs (three Class 0, five Class I, six Class II, and two Class III) and two are extragalactic candidates.We find that thermal dust emission generally contributes less that 30% of the emission at 10GHz. The radio emission is dominated by other types of emission such as gyro-synchrotron radiation from active magnetospheres, free-free emission from thermal jets, free-free emission from the outflowing photo-evaporated disk material, and/or synchrotron emission from accelerated cosmic-rays in jet or protostellar surface shocks. These different types of emission could not be clearly disentangled. Our non-detections towards Class II/III disks suggest that extreme UV-driven photoevaporation is insufficient to explain the disk dispersal, assuming that the contribution of UV photoevaporating stellar winds to radio flux does not evolve with time. The sensitivity of our data cannot exclude photoevaporation due to X-ray photons as an efficient mechanism for disk dispersal. Deeper surveys with the Square Kilometre Array will be able to provide strong constraints on disk photoevaporation.
- ID:
- ivo://CDS.VizieR/J/AJ/126/119
- Title:
- Optical and radio data for rich Abell clusters
- Short Name:
- J/AJ/126/119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical observations and radio continuum imaging data for a sample of rich, X-ray-bright Abell clusters at intermediate (z~0.2) redshifts. We find that the radio galaxy population varies substantially from cluster to cluster within this homogeneous sample. The spatial distribution of the high-luminosity radio galaxies (HLRGs; L1.4>10^23^W/Hz) is very different from the low-luminosity radio galaxies (LLRGs; L1.4<=10^22.75^W/Hz), with the LLRGs displaying a flat spatial distribution in contrast to the centrally peaked HLRGs. A color-morphology classification shows that the HLRGs are composed primarily of galaxies with old stellar populations, whereas the LLRGs have a much more diverse composition. We do not see a correlation between the cluster radio fraction and cluster blue fraction. However, there is a moderate anticorrelation with richness, suggesting that a rich cluster is less likely to have radio-bright galaxies, whether the radio emission is due to active galactic nuclei or star formation.
- ID:
- ivo://CDS.VizieR/J/A+AS/115/75
- Title:
- Optical astrometry of Benchmark radio sources. III
- Short Name:
- J/A+AS/115/75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Optical positions, relative to the International Reference Stars catalogue (IRS), and therefore in the system of the FK5, have been obtained for the optical counterparts of 35 extragalactic radio sources south of {delta}~+3deg. Many of these sources are being considered as possible Benchmark objects for the establishment of a quasi-inertial unified radio/optical reference frame. Precision levels better than 0.2" in both coordinates were achieved. A comparison with VLBI radio positions available for these sources is presented. We give evidence for a possible offset in RA between the radio and optical reference frames.
- ID:
- ivo://CDS.VizieR/J/AZh/72/613
- Title:
- Optical identification of radio sources
- Short Name:
- J/AZh/72/613
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Results are presented of deep identifications of 40 steep spectrum radio sources detected on RATAN-600 in an area ~100deg in the 'Kholod' experiment and then studied using the VLA. Candidates for optical objects responsible for the radio emission were found for 32 sources. With the exception of a few quasars and objects with ill-defined morphology, a large fraction of the radio sources are associated either with gE galaxies or with galaxies of an unknown nature.
- ID:
- ivo://CDS.VizieR/J/AZh/71/684
- Title:
- Optical Identification of RC and UTRAO Catalogs
- Short Name:
- J/AZh/71/684
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Two hundred and forty radio sources that are common for RC (RATAN-600) and UTRAO (VLA, Douglas J.N.+, 1980PAUTx..17....1D) catalogs were identified on the enlarged prints of the Palomar Sky Atlas. The number of identified radio sources with flux density between 15 and 300 mJy drops with decreasing flux density in the centimeter wavelength range.
- ID:
- ivo://CDS.VizieR/J/A+AS/115/1
- Title:
- Optical identification of S5 catalog
- Short Name:
- J/A+AS/115/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Optical identifications, magnitudes, and redshifts have been compiled for the 185 radio sources of the S5 catalogue, representing its current optical identification status. Reliable optical counterparts are found for more than 75% of the sources, nearly 50% of which have measured redshifts. Our tabulation also includes radio positions, radio fluxes, and radio spectral indices. References to other catalogues and detailed supplementary notes are given for a large fraction of the sources.
- ID:
- ivo://CDS.VizieR/J/A+AS/103/349
- Title:
- Optical identification of S4 sources
- Short Name:
- J/A+AS/103/349
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An update of the optical identification status of the S4 radio source catalogue is presented. An extensive literature search has been made to gather the types of the optical counterparts, their magnitudes and redshifts. As far as possible, references to other optical catalogues are given for these data, which are often supplemented by more detailed notes on individual sources. Accurate radio positions taken from the literature are given for a large fraction of the sources.
- ID:
- ivo://CDS.VizieR/J/MNRAS/227/607
- Title:
- Optical identifications of Molonglo sources
- Short Name:
- J/MNRAS/227/607
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Optical identifications have been sought for 304 radio sources from the declination -20{deg} region of the first Molonglo deep survey. Optical objects have been measured using the Palomar sky survey to an accuracy of 1 arcsec and magnitude estimates are to 0.4mag. Finding charts are given for all fields with optical objects within +/-2{sigma} of the radio position. Sixteen QSOs have been confirmed (details have been reported elsewhere) amongst the blue stellar-like objects and spectroscopy is complete to m_o_=19.5. The mean magnitude of the QSOs is 19.2 and the mean redshift is 1.34. A study of the background densities of objects indicates that about half of the remaining blue stellar-like objects are QSOs and about 80 per cent of the galaxies are associated with the radio emission. The QSOs are amongst the fainter and the bluer of the blue stellar-like objects. There is no evidence for any average offset between the radio and optical positions.
- ID:
- ivo://CDS.VizieR/J/A+AS/115/11
- Title:
- Optical identifications of radio sources
- Short Name:
- J/A+AS/115/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CCD images of the fields of 115 radio sources from the 1Jy, S4 and S5 catalogues are presented. New optical counterparts have been found for a total of 34 sources, a large fraction of which had as yet only been described as empty fields on Sky Survey Plates. Of the 54 radio sources with previously published identifications, 50 optical counterparts have been confirmed while for 4 sources new identifications are proposed. R band magnitudes, derived from the CCD images, are provided for all but a few identified optical counterparts. The fields at the positions of 27 radio sources are still empty down to a limiting magnitude of at least m_R_=22mag, requiring much deeper optical as well as additional infrared images for establishing their optical counterparts.
