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Observed HI accretion around nearby galaxies can only account for a fraction of the gas supply needed to sustain the currently observed star formation rates. It is possible that additional accretion happens in the form of low column density…

Astrophysics of Galaxies · Physics 2014-10-01 W. J. G. de Blok , Katie M. Keating , D. J. Pisano , F. Fraternali , F. Walter , T. Oosterloo , E. Brinks , F. Bigiel , A. Leroy

Aims: We offer a new, simpler picture of the local interstellar medium, made of a single continuous cloud enveloping the Sun. This new outlook enables the description of a diffuse cloud from within and brings to light some unexpected…

Astrophysics of Galaxies · Physics 2014-09-05 Cecile Gry , Edward B. Jenkins

The Square Kilometre Array mid-frequency array will enable high-redshift detections of neutral hydrogen (HI) emission in galaxies, providing important constraints on the evolution of cold gas in galaxies over cosmic time. Strong…

Astrophysics of Galaxies · Physics 2024-09-12 Roger P. Deane , Tariq Blecher , Danail Obreschkow , Ian Heywood

We obtained VLA 21-cm observations of the galaxy ESO 481-G017 to determine the environment and trigger of remote star formation traced by a HII region found 43 kpc from the galaxy (in projection). ESO 481-G017 is an early type spiral galaxy…

Cosmology and Nongalactic Astrophysics · Physics 2009-09-07 N. Santiago-Figueroa , M. Putman , J. Werk , E. Ryan-Weber , G. Meurer

HI 1225+01 is an intergalactic gas cloud located on the outskirts of Virgo cluster. Its main components are two large clumps of comparable HI masses (M_HI ~ 10^9 Msun) separated by about 100 kpc. One of the clumps hosts a blue…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 Y. Matsuoka , N. Ienaka , S. Oyabu , K. Wada , S. Takino

We present a catalog of 59 ultra-compact high velocity clouds (UCHVCs) extracted from the 40% complete ALFALFA HI-line survey. The ALFALFA UCHVCs have median flux densities of 1.34 Jy km/s, median angular diameters of 10', and median…

Cosmology and Nongalactic Astrophysics · Physics 2013-04-18 Elizabeth A. K. Adams , Riccardo Giovanelli , Martha P. Haynes

We present the analysis of the diffuse, low column density HI environment of 18 MHONGOOSE galaxies. We obtained deep observations with the Robert C. Byrd Green Bank Telescope, and reached down to a 3sigma column density detection limit of…

Astrophysics of Galaxies · Physics 2021-04-07 Amy Sardone , D. J. Pisano , N. M. Pingel , Amidou Sorgho , Claude Carignan , W. J. G. de Blok

We report the results of an HI blind survey of 80deg^2 of the Virgo cluster, based on the 08deg < delta < 16 deg strip of ALFALFA, the Arecibo Legacy Fast ALFA Survey. 187 HI sources of high significance are found providing a complete…

We report the discovery and follow-up observations of a system of three objects identified by the ALFALFA extragalactic HI survey, cataloged as (almost) dark extragalactic sources, i.e., extragalactic HI detections with no discernible…

We present Far Ultraviolet Spectroscopic Explorer (FUSE) observations of interstellar molecular hydrogen (H_2) in two Galactic high-velocity clouds (HVCs). Molecular hydrogen absorption is detected in the Magellanic Stream (abundance ~0.3…

Astrophysics · Physics 2009-11-07 Philipp Richter , Kenneth R. Sembach , Bart P. Wakker , Blair D. Savage

We present the largest catalogue to date of optical counterparts for HI radio-selected galaxies, Hopcat. Of the 4315 HI radio-detected sources from the HI Parkes All Sky Survey (Hipass) catalogue, we find optical counterparts for 3618 (84%)…

It has been suggested that high velocity clouds may be distributed throughout the Local Group and are therefore not in general associated with the Milky Way galaxy. With the aim of testing this hypothesis, we have made observations in the…

Astrophysics · Physics 2009-11-07 S. L. Tufte , J. D. Wilson , G. J. Madsen , L. M. Haffner , R. J. Reynolds

We report on neutral hydrogen observations of a ~ 5.5 x 5.5 degree field around the NGC 1566 galaxy group with the multibeam narrow-band system on the 64-m Parkes telescope. We detected thirteen HI sources in the field, including two…

The consortium for Galactic studies with the Arecibo L-band Feed Array (ALFA) is conducting a neutral hydrogen (HI) survey of the whole Arecibo sky (declination range from -1 to 38 degrees), with high angular (3.5') and velocity resolution…

We present results of two 21-cm HI surveys performed with the Australia Telescope Compact Array in the nearby Centaurus A and Sculptor galaxy groups. These surveys are sensitive to compact HI clouds and galaxies with HI masses as low as…

Astrophysics · Physics 2009-11-07 W. J. G. de Blok , M. A. Zwaan , M. Dijkstra , F. H. Briggs , K. C. Freeman

We combine the catalogs of compact high-velocity HI clouds extracted from the LDS and HIPASS surveys and analyze the all-sky properties of the ensemble. Five principal observables are defined for the CHVC population: (1) the spatial…

Astrophysics · Physics 2009-11-07 V. de Heij , R. Braun , W. B. Burton

We present a Parkes multibeam \HI survey of the Large Magellanic Cloud (LMC). This survey, which is sensitive to spatial structure in the range 200 pc to 10 kpc, complements the Australia Telescope Compact survey, which is sensitive to…

Astrophysics · Physics 2009-01-01 L. Staveley-Smith , S. Kim , M. R. Calabretta , R. F. Haynes , M. J. Kesteven

The Spitzer Space Telescope (formerly SIRTF) extragalactic First-Look Survey covered about 5 square degrees centered on J2000 17:18 +59:30 in order to characterize the infrared sky with high sensitivity. We used the 100-m Green Bank…

Astrophysics · Physics 2009-11-10 Felix J. Lockman , J. J. Condon

Simulations of an isolated Milky Way-like galaxy, in which supernovae power a galactic fountain, reproduce the observed velocity and 21cm brightness statistics of galactic neutral hydrogen (HI). The simulated galaxy consists of a thin HI…

Astrophysics · Physics 2012-03-19 C. M. Booth , Tom Theuns

We have conducted wide-field HI mapping of a ~5.5 x 5.5 degree region surrounding the NGC 3783 galaxy group, to an HI mass limit of ~4 x 10^8 Msun. The observations were made using the multibeam system on the Parkes 64-m radiotelescope, as…