- ID:
- ivo://CDS.VizieR/J/A+A/606/A142
- Title:
- L1544 1.2 and 2mm emission maps
- Short Name:
- J/A+A/606/A142
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In dense and cold molecular clouds dust grains are surrounded by thick icy mantles. It is however not clear if dust growth and coagulation take place before the switch-on of a protostar. This is an important issue, as the presence of large grains may affect the chemical structure of dense cloud cores, including the dynamically important ionization fraction, and the future evolution of solids in protoplanetary disks. To study this further, we focus on L1544, one of the most centrally concentrated pre-stellar cores on the verge of star formation, and with a well-known physical structure. We observed L1544 at 1.2 and 2mm using NIKA, a new receiver at the IRAM 30 m telescope, and we used data from the Herschel Space Observatory archive. We find no evidence of grain growth towards the center of L1544 at the available angular resolution. Therefore, we conclude that single dish observations do not allow us to investigate grain growth towards the pre-stellar core L1544 and high sensitivity interferometer observations are needed. We predict that dust grains can grow to 200um in size toward the central ~300au of L1544. This will imply a dust opacity change by a factor of ~2.5 at 1.2mm, which can be detected using the Atacama Large Millimeter and submillimeter Array (ALMA) at different wavelengths and with an angular resolution of 2".
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/537/A99
- Title:
- Large Quasar Astrometric Catalogue 2 (LQAC-2)
- Short Name:
- J/A+A/537/A99
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- First of all we make a substantial review of the definitions and properties of quasars and AGN (Active Galactic Nuclei), the differenciation of these objects being unclear in the literature and even for specialists. This will serve our purpose when deciding which kinds of objects will be taken into account in our compilation. Then we carry out the cross-identification between the 9 catalogues of quasars chosen for their accuracy and their huge number of objects, using a flag for each of them, and including all the available data related to magnitudes (infrared and optical), radiofluxes and redshifts. We also perform cross identification with external catalogues 2MASS, B1.0 and GSC2.3 in order to complete photometric data of the objects. Moreover we compute the absolute magnitude of our extragalactic objects by taking into account the recent studies concerning the galactic absorption. In addition substantial improvements are brought with respect to the first release of the LQAC (Souchay et al., 2009, Cat. J/A+A/494/799). At first a LQAC name is given for each object based on its equatorial coordinates with respect to the ICRS, following a procedure which creates no ambiguity for identification. At second the equatorial coordinates of the objects are recomputed more accurately according to the algorithms used for the elaboration of the Large Quasar Reference Frame (LQRF) (Andrei et al., 2009, Cat. I/313). At third we introduce a morphological classification for the objects which enables in particular to define clearly if the object is point-like or extended. Our final catalogue, called LQAC-2, contains 187 504 quasars. This is roughly larger than the 113 666 quasars recorded in the first version of the LQAC (Souchay et al., 2009, Cat. J/A+A/494/799) and a little more than the number of quasars recorded in the up-dated version of the Veron Cetty and Veron (2010, Cat. VII/258) catalogue, which was the densest compilation of quasars up to now. In addition to the quantitative and qualitative improvements brought by our compilation, we discuss the homogeneity of the data and carry out statistical analysis concerning the spatial density and the distance to the closest neighbour.
- ID:
- ivo://CDS.VizieR/J/A+A/583/A75
- Title:
- Large Quasar Astrometric Catalogue 3 (LQAC-3)
- Short Name:
- J/A+A/583/A75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- From an astrometric point of view, quasars constitute quasi-ideal reference objects in the celestial sphere, with an a priori absence of proper motion. Since the second release of the Large Quasar Astrometric Catalog (LQAC), a large number of quasars have been discovered, in particular with the upcoming new release of the SDSS quasars catalog. Following the same procedure as in the two previous releases of the LQAC, our aim was to compile all the quasars recorded until the present date, with accurate recomputation of their equatorial coordinates in the ICRS and with the maximum of information concerning their physical properties, such as the redshift, the photometry, and the absolute magnitudes.
- ID:
- ivo://CDS.VizieR/J/A+A/494/799
- Title:
- Large Quasar Astrometric Catalogue (LQAC)
- Short Name:
- J/A+A/494/799
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The very large and increasing number of quasars reckoned from various sky surveys leads to a large quantity of data which brings various and inhomogeneous information in the fields of astrometry, photometry, radioastronomy and spectroscopy. In this paper, we describe our work that aims to make available a general compilation of the largest number of recorded quasars obtained from all the available catalogues, with their best position estimates, and providing physical information at both optical and radio wavelengths.
- ID:
- ivo://CDS.VizieR/J/A+A/652/A77
- Title:
- Large scale [CII] emission from the OMC
- Short Name:
- J/A+A/652/A77
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The [CII] 158um far-infrared (FIR) fine-structure line is one of the dominant cooling lines of the star-forming interstellar medium (ISM). Hence [CII] emission originates in, and thus can be used to trace a range of ISM processes. Velocity resolved large scale mapping of [CII] in star forming regions provides a unique perspective on the kinematics of these regions and their interactions with the exciting source of radiation. In this paper we explore the scientific applications of large scale mapping velocity resolved [CII] observations. With [CII] observations we investigate the influence of stellar feedback on the ISM. We present the details of observation, calibration and data reduction using a heterodyne array receiver mounted on an airborne observatory. A 1.15 square degree velocity resolved map of Orion molecular cloud centred on the bar region was observed using the upGREAT heterodyne receiver flying on-board the Stratospheric Observatory for Infrared Astronomy (SOFIA). The data was acquired using the 14 pixels of the German REceiver for Astronomy at Terahertz Frequencies (upGREAT) observing in an on-the-fly mapping mode. 2.4 million spectra were taken in total. These spectra were gridded into a three dimensional cube with a spatial resolution of 14.1 arcseconds and spectral resolution of 0.3km/s.
756. LARGESS survey
- ID:
- ivo://CDS.VizieR/J/MNRAS/464/1306
- Title:
- LARGESS survey
- Short Name:
- J/MNRAS/464/1306
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the Large Area Radio Galaxy Evolution Spectroscopic Survey (LARGESS), a spectroscopic catalogue of radio sources designed to include the full range of radio AGN populations out to redshift z~0.8. The catalogue covers ~800deg^2^ of sky, and provides optical identifications for 19179 radio sources from the 1.4GHz Faint Images of the Radio Sky at Twenty-cm (FIRST) survey down to an optical magnitude limit of i_mod_<20.5 in Sloan Digital Sky Survey (SDSS) images. Both galaxies and point-like objects are included, and no colour cuts are applied. In collaboration with the WiggleZ and Galaxy And Mass Assembly (GAMA) spectroscopic survey teams, we have obtained new spectra for over 5000 objects in the LARGESS sample. Combining these new spectra with data from earlier surveys provides spectroscopic data for 12329 radio sources in the survey area, of which 10 856 have reliable redshifts. 85 per cent of the LARGESS spectroscopic sample are radio AGN (median redshift z=0.44), and 15 per cent are nearby star-forming galaxies (median z=0.08). Low-excitation radio galaxies (LERGs) comprise the majority (83 per cent) of LARGESS radio AGN at z<0.8, with 12 per cent being high-excitation radio galaxies (HERGs) and 5 per cent radio-loud QSOs. Unlike the more homogeneous LERG and QSO sub-populations, HERGs are a heterogeneous class of objects with relatively blue optical colours and a wide dispersion in mid-infrared colours. This is consistent with a picture in which most HERGs are hosted by galaxies with recent or ongoing star formation as well as a classical accretion disc.
- ID:
- ivo://CDS.VizieR/J/MNRAS/414/2528
- Title:
- LBA Calibrator Survey (LCS1)
- Short Name:
- J/MNRAS/414/2528
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalogue of accurate positions and correlated flux densities for 410 flat-spectrum, compact extragalactic radio sources previously detected in the AT20G survey. The catalogue spans the declination range [-90{deg}, -40{deg}] and was constructed from four 24-hour VLBI observing sessions with the Australian Long Baseline Array at 8.3GHz. The VLBI detection rate in these experiments is 97%, the median uncertainty of the source positions is 2.6mas, and the median correlated flux density on projected baselines longer than 1000km is 0.14Jy. The goals of this work are 1) to provide a pool of southern sources with positions accurate to a few milliarcsec, which can be used for phase referencing observations, geodetic VLBI and space navigation; 2) to extend the complete flux-limited sample of compact extragalactic sources to the southern hemisphere; and 3) to investigate the parsec-scale properties of high-frequency selected sources from the AT20G survey. As a result of this VLBI campaign, the number of compact radio sources south of declination -40 deg which have measured VLBI correlated flux densities and positions known to milliarcsec accuracy has increased by a factor of 3.5. The catalogue and supporting material is available at http://astrogeo.org/lcs1.
- ID:
- ivo://CDS.VizieR/J/A+A/604/A20
- Title:
- L1157-B1 DCN (2-1) and H^13^CN (2-1) datacubes
- Short Name:
- J/A+A/604/A20
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We performed high-angular-resolution observations toward L1157-B1 with the IRAM NOEMA interferometer of the DCN (2-1) and H^13^CN (2-1) lines to compute the deuterated fraction, D_frac_(HCN), and compare it with previously reported D_frac_ of other molecular species. Our aim is to observationally investigate the role of the different chemical processes at work that lead to formation of the DCN and compare it with HDCO, the two deuterated molecules imaged with an interferometer, and test the predictions of the chemical models for their formation.
- ID:
- ivo://CDS.VizieR/J/ApJS/174/481
- Title:
- 2LC Compact Radio Sources in the galactic center
- Short Name:
- J/ApJS/174/481
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used the VLA at 1.4GHz to survey the inner 2{deg} of the Galactic center for radio pulsar candidates. Because of the large pulse broadening suffered by Galactic center radio pulsars, our strategy has been to identify compact radio sources, without regard to whether they are pulsed radio sources. We describe our survey and present the catalog of 170 sources. Comparison with other radio surveys of the area shows that just over half of these sources have not been detected previously; this same comparison reveals 29 sources that are not in higher frequency surveys, suggesting that the sources are either variable or steep spectrum, and a comparable number of sources in other surveys that should have been detected in this survey but were not. Comparison with infrared surveys shows that 59 (35%) sources have infrared counterparts and are likely to be HII regions.
- ID:
- ivo://CDS.VizieR/J/A+A/632/A115
- Title:
- L1188 HCO+, 12CO and 13CO datacubes
- Short Name:
- J/A+A/632/A115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In order to search for further observational evidence of cloud-cloud collisions in one of the promising candidates, L1188, we carried out observations of multiple molecular lines toward the intersection region of the two nearly orthogonal filamentary molecular clouds in L1188. Based on these observations, we find two parallel filamentary structures, both of which have at least two velocity components being connected with broad bridging features. We also found a spatially complementary distribution between the two molecular clouds, as well as enhanced ^13^CO emission and ^12^CO self-absorption toward their abutting regions. At the most blueshifted velocities, we unveiled a 1pc-long arc ubiquitously showing ^12^CO line wings. We discovered two 22GHz water masers, which are the first maser detections in L1188. An analysis of line ratios at a linear resolution of 0.2 pc suggests that L1188 is characterised by kinetic temperatures of 13-23K and H_2_ number densities of 10^3^-10^3.6^cm^-3^. On the basis of previous theoretical predictions and simulations, we suggest that these observational features can be naturally explained by the scenario of a cloud-cloud collision in L1188, although an additional contribution of stellar feedback from low-mass young stellar objects cannot be ruled out.