- ID:
- ivo://CDS.VizieR/J/A+A/627/A106
- Title:
- HI observations of AT 2018cow
- Short Name:
- J/A+A/627/A106
- Date:
- 23 Mar 2022 16:27:48
- Publisher:
- CDS
- Description:
- Unusual stellar explosions represent an opportunity to learn about both stellar and galaxy evolution. Mapping the atomic gas in host galaxies of such transients can lead to an understanding of the conditions triggering them. We provide resolved atomic gas observations of the host galaxy, CGCG137-068, of the unusual, poorly-understood transient AT2018cow searching for clues to understand its nature. We test whether it is consistent with a recent inflow of atomic gas from the intergalactic medium, as suggested for host galaxies of gamma-ray bursts (GRBs) and some supernovae (SNe). We observed the HI hyperfine structure line of the AT2018cow host with the Giant Metrewave Radio Telescope. There is no unusual atomic gas concentration near the position of AT2018cow. The gas distribution is much more regular than those of GRB/SN hosts. The AT2018cow host has an atomic gas mass lower by 0.24dex than predicted from its star formation rate (SFR) and is at the lower edge of the galaxy main sequence. In the continuum we detected the emission of AT2018cow and of a star-forming region in the north-eastern part of the bar (away from AT2018cow). This region hosts a third of the galaxy's SFR. The absence of atomic gas concentration close to AT2018cow, along with a normal SFR and regular HI velocity field, sets CGCG137-068 apart from GRB/SN hosts studied in HI. The environment of AT2018cow therefore suggests that its progenitor may not have been a massive star. Our findings are consistent with an origin of the transient that does not require a connection between its progenitor and gas concentration or inflow: an exploding low-mass star, a tidal disruption event, a merger of white dwarfs, or a merger between a neutron star and a giant star. We interpret the recently reported atomic gas ring in CGCG137-068 as a result of internal processes connected with gravitational resonances caused by the bar.
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Search Results
- ID:
- ivo://CDS.VizieR/II/354
- Title:
- HIP and TGAS stars reddening and extinction
- Short Name:
- II/354
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- These reddening and interstellar extinction estimates are a result of a series of studies presented in the papers 2009AstL...35..780G, 2010AstL...36..584G, 2012AstL...38...12G, 2012AstL...38...87G, 2017AstL...43..472G and finally 2017MNRAS.472.3805G and 2018MNRAS.475.1121G. The key basis of these estimates is the 3D reddening map of Gontcharov (2017AstL...43..472G, 2017PAZh...43..521G, Cat. J/PAZh/43/521). This map has been tested among eight sources of reddening and extinction estimates for nearly 60,000 Gaia DR1 TGAS main sequence stars younger than 3Gyr with a relative error of the Gaia parallax less than 0.1. The sources are tested in their ability to put the stars among the PARSEC and MIST theoretical isochrones in the Hertzsprung-Russell diagram based on the precise Gaia, Tycho-2, 2MASS and WISE photometry. The 3D reddening map of Gontcharov provides both the minimal number of outliers bluer than any reasonable isochrone and the correct number of stars younger than 3Gyr in agreement with the Besancon Galaxy model. In another test Gaia DR1 TGAS parallaxes, Tycho-2 photometry and reddening/extinction estimates from nine data sources for 38,074 giants within 415pc from the Sun are used to compare their position in the Hertzsprung-Russell diagram with theoretical estimates, which are based on the PARSEC and MIST isochrones and the TRILEGAL model of the Galaxy with its parameters being widely varied. We conclude that, again, the estimates from the 3D reddening map of Gontcharov, including the median reddening E(B-V)=0.06mag at |b|>50{deg}, give the best fit of the empirical and theoretical data with each other. Based on these studies we present here the best up-to-date reddening, extinction and extinction-to-reddening estimates for the Gaia DR1 TGAS and Hipparcos stars within 415pc from the Sun. The accuracy of the E(B-V) estimates is proved to be better than 0.04mag everywhere in this space.
- ID:
- ivo://CDS.VizieR/J/AJ/123/873
- Title:
- HIPASS high-velocity clouds
- Short Name:
- J/AJ/123/873
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A catalog of southern anomalous-velocity HI clouds at {delta}<+2{deg} is presented. This catalog is based on data from the HI Parkes All-Sky Survey (HIPASS) reprocessed with the MINMED5 procedure and searched with a new high-velocity cloud-finding algorithm. The improved sensitivity (5{sigma}: {Delta}T_B_=0.04K), resolution (15.5'), and velocity range (-500km/s<V_LSR_<+500km/s) of the HIPASS data result in a substantial increase in the number of individual clouds (1956, as well as 41 galaxies) compared with what was known from earlier southern data. The method of cataloging the anomalous-velocity objects is described, and a catalog of key cloud parameters, including velocity, angular size, peak column density, total flux, position angle, and degree of isolation, is presented.
- ID:
- ivo://CDS.VizieR/J/A+A/594/A116
- Title:
- HI4PI spectra and column density maps
- Short Name:
- J/A+A/594/A116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Measurement of the Galactic neutral atomic hydrogen (HI) column density, NHI, and brightness temperatures, Tb, is of high scientific value for a broad range of astrophysical disciplines. In the past two decades, one of the most-used legacy HI datasets has been the Leiden/Argentine/Bonn Survey (LAB). We release the HI 4-pi survey (HI4PI), an all-sky database of Galactic HI, which supersedes the LAB survey. The HI4PI survey is based on data from the recently completed first coverage of the Effelsberg-Bonn HI Survey (EBHIS) and from the third revision of the Galactic All-Sky Survey (GASS). EBHIS and GASS share similar angular resolution and match well in sensitivity. Combining both, they are ideally suited to be a successor to LAB. The new HI4PI survey outperforms the LAB in angular resolution (16.1', FWHM) and sensitivity (43mK RMS). Moreover, it has full spatial sampling and thus overcomes a major issue of LAB, which severely undersamples the sky. We publish all-sky column density maps of the neutral atomic hydrogen in the Milky Way, along with full spectroscopic data, in several map projections including HEALPix.
- ID:
- ivo://CDS.VizieR/J/ApJ/626/195
- Title:
- HI self-absorption (HISA) survey in the CGPS
- Short Name:
- J/ApJ/626/195
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a 21cm line HI self-absorption (HISA) survey of cold atomic gas within Galactic longitudes l=75{deg} to 146{deg} and latitudes b=-3{deg} to +5{deg}. We identify HISA as spatially and spectrally confined dark HI features and extract it from the surrounding HI emission in the arcminute-resolution Canadian Galactic Plane Survey (CGPS). We compile a catalog of the most significant features in our survey and compare our detections against those in the literature. Within the parameters of our search, we find nearly all previously detected features and identify many new ones.
- ID:
- ivo://CDS.VizieR/J/A+A/550/A23
- Title:
- HI shells in Leiden/Argentina/Bonn HI survey
- Short Name:
- J/A+A/550/A23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyse the all-sky Leiden/Argentina/Bonn HI survey, where we identify shells belonging to the Milky Way. We used an identification method based on the search of continuous regions of a low brightness temperature that are compatible with given properties of HI shells. We found 333 shells in the whole Galaxy. The size distribution of shells in the outer Galaxy is fitted by a power law with the coefficient of 2.6 corresponding to the index 1.8 in the distribution of energy sources. Their surface density decreases exponentially with a scale length of 2.8kpc. The surface density of shells with radii >100pc in the solar neighbourhood is around 4 per kpc^2^ and the 2D porosity is around 0.7.
- ID:
- ivo://CDS.VizieR/J/A+A/437/101
- Title:
- HI shells in the outer Milky Way
- Short Name:
- J/A+A/437/101
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of a method for an automatic search for HI shells in 3D data cubes and apply it to the Leiden-Dwingeloo HI survey of the northern Milky Way. In the 2nd Galactic quadrant, where identifications of structures are not substantially influenced by overlapping, we find nearly 300 structures.
- ID:
- ivo://CDS.VizieR/J/A+A/658/A103
- Title:
- History independent tracers
- Short Name:
- J/A+A/658/A103
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Molecular line emission is a powerful probe of the physical conditions of astrophysical objects but can be complex to model and it is often unclear which transitions would be the best targets for observers who wish to constrain a given parameter. We produce a list of molecular species for which the gas history can be ignored, removing a major modelling complexity. We then determine the best of these species to observe in order to constrain various physical parameters. We use a large set of chemical models with different chemical histories to determine which species have abundances at 1 MYr which are insensitive to the initial conditions. We then use radiative transfer modelling to produce the intensity of every transition of these molecules. We finally compute the mutual information between the physical parameters and all transitions and transition ratios in order to rank their usefulness in determining the value of a given parameter. We find 48 species which are insensitive to the chemical history of the gas, 23 of which have collisional data available. We produce a ranked list of all transitions and ratios of these species by their mutual information with various gas properties. We show mutual information is an adequate measure of how well a transition can constrain a physical parameter by recovering known probes and demonstrating random forest regression models become more accurate predictors when high scoring features are included. Therefore, this list can be used to select target transitions for observations in order to maximise knowledge about those physical parameters.
- ID:
- ivo://CDS.VizieR/J/A+A/564/A116
- Title:
- HI supershells catalogue
- Short Name:
- J/A+A/564/A116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The HI supershells catalogue was carried out making use of the Leiden-Argentine-Bonn (LAB) HI survey in the outer part of the Galaxy. The identification of the supershell candidates was made using a combination of two techniques: a visual inspection one plus an automatic searching algorithm. A total of 566 supershell candidates were identified. Most of them (347) are located in the second galactic quadrant, while 219 were found in the third one.
- ID:
- ivo://CDS.VizieR/J/A+AS/52/63
- Title:
- H I Survey of the Galactic Center Region
- Short Name:
- J/A+AS/52/63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Presented here are 21-cm (1.42GHz) observations of neutral hydrogen emission from the core of our Galaxy made over a period of several years with the 140-foot telescope of the National Radio Astronomy Observatory. The survey covers the region 348 < l < 10, -10 < b < 10 with an angular resolution of 21' and a grid spacing of 0.5 degrees in both l and b, and the velocity range |v| < 310 km/s with a kinematic resolution of 5.5 km/s. The sensitivity of the data generally corresponds to an antenna-temperature rms level of 0.02 K or better. The H I spectra from the survey are archived in a single three-dimensional (v, l, b) data cube in FITS image format. There are 224 velocity channels with a step of 2.75 km/s between channels. The intensities are given in units of antenna temperature and can be converted to brightness temperature units by multiplying by a factor of (1.52).
