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A head-tail high-velocity cloud (HVC) is a neutral hydrogen halo cloud that appears to be interacting with the diffuse halo medium as evident by its compressed head trailed by a relatively diffuse tail. This paper presents a sample of 116…

Astrophysics of Galaxies · Physics 2015-05-30 M. E. Putman , D. R. Saul , E. Mets

We describe a population of small, high velocity, atomic hydrogen clouds, loops, and filaments found above and below the disk near the Galactic Center. The objects have a mean radius of 15 pc, velocity widths of $\sim 14$ km/s and are…

Astrophysics of Galaxies · Physics 2015-06-15 N. M. McClure-Griffiths , J. A. Green , A. S. Hill , F. J. Lockman , J. M. Dickey , B. M. Gaensler , A. J. Green

We present deep HI observations of the moderately inclined spiral galaxy, NGC 2997. The goal of these observations was to search for HI clouds in the vicinity of NGC 2997 analogous to the high velocity clouds of the Milky Way and gain…

Astrophysics of Galaxies · Physics 2009-06-25 Kelley M. Hess , D. J. Pisano , Eric M. Wilcots , Jayaram N. Chengular

We perform an analysis of the spatial clustering properties of HI selected galaxies from the HI Parkes All Sky Survey (HIPASS) using the formalism of the halo occupation distribution (HOD). The resulting parameter constraints show that the…

Cosmology and Nongalactic Astrophysics · Physics 2009-08-21 Stuart Wyithe , Michael J. I. Brown , Martin A. Zwaan , Martin J. Meyer

The neutral hydrogen structure of high-velocity cloud A0 (at about -180 km/s) has been mapped with a 9.1 arcmin resolution. Gaussian decomposition of the profiles is used to separately map families of components defined by similarities in…

Astrophysics of Galaxies · Physics 2015-06-15 Gerrit L. Verschuur

High-velocity clouds (HVCs) are interstellar gas clouds whose velocities are incompatible with Galactic rotation. Since the first discovery of HVCs in 1963, their origins have been debated for decades but are still not settled down, because…

Astrophysics of Galaxies · Physics 2025-06-19 Yu-Ting Wang , Chao Liu , Zhi-Yu Zhang

This study developed an automated identification procedure for compact clouds with broad velocity widths in the spectral line data cubes of highly crowded regions. The procedure was applied to the CO J=3-2 line data, obtained using the…

Astrophysics of Galaxies · Physics 2022-09-27 Tomoharu Oka , Asaka Uruno , Rei Enokiya , Taichi Nakamura , Yuto Yamasaki , Yuto Watanabe , Sekito Tokuyama , Yuhei Iwata

It was proposed by Blitz et al. (1999) that High Velocity Clouds (HVCs) are remnants of Local Group formation and the average distance of HVCs is 1 Mpc, which is the result of a simple dynamical calculation leading to match the observed…

Astrophysics · Physics 2016-08-30 Kui-Yun Huang , Ing-Guey Jiang

New observations of the neutral hydrogen (HI) in and around the line of sight of the Sculptor dwarf spheroidal (dSph) are presented. The data obtained with the single-dish Parkes telescope cover a large area of 7\degr x 7\degr in the…

Astrophysics · Physics 2009-11-07 Antoine Bouchard , Claude Carignan , Sergey Mashchenko

We present Arecibo, GBT, VLA and WIYN/pODI observations of the ALFALFA source AGC 226067. Originally identified as an ultra-compact high velocity cloud and candidate Local Group galaxy, AGC 226067 is spatially and kinematically coincident…

We offer a new, more inclusive, picture of the local interstellar medium, where it is composed of a single, monolithic cloud that surrounds the Sun in all directions. Our study of velocities based on Mg II and Fe II ultraviolet absorption…

Astrophysics of Galaxies · Physics 2015-06-23 Cecile Gry , Edward B. Jenkins

Using data from the Arecibo Galaxy Environment Survey, we report the discovery of five HI clouds in the Leo I group without detected optical counterparts. Three of the clouds are found midway between M96 and M95, one is only 10$^{\prime}$…

We present HI imaging of GBT 1355+5439 performed with the Westerbork Synthesis Radio Telescope. This is a dark HI object recently discovered close to the nearby galaxy M101. We find GBT 1355+5439 to be an HI cloud 5x3 arcmin in size. The…

Astrophysics of Galaxies · Physics 2015-06-16 T. A. Oosterloo , G. H. Heald , W. J. G. de Blok

We present a pilot HI survey of 17 Planck Galactic Cold Clumps (PGCCs) with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). HI Narrow Self-Absorption (HINSA) is an effective method to detect cold HI being mixed with…

We found that an intermediate velocity cloud (IVC) IVC 86-36 in HI 21 cm emission shows a head-tail distribution toward the Galactic plane with marked parallel filamentary streamers, which is extended over 40 degrees in the sky. The…

We present 21 cm observations of a 10 $\times$ 2 degree region in the Virgo cluster, obtained as part of the Arecibo Galaxy Environment Survey. 289 sources are detected over the full redshift range (-2,000 $<$ $v$$_{hel}$ $<$ + 20,000 km/s)…

Astrophysics of Galaxies · Physics 2015-06-04 R. Taylor , J. I. Davies , R. Auld , R. F. Minchin

The blind HI survey Arecibo Galaxy Environment Survey (AGES) detected several unresolved sources in the Virgo cluster, which do not have optical counterparts in the Sloan Digital Sky Survey. The origin of these dark clouds is unknown. They…

Astrophysics of Galaxies · Physics 2020-10-14 Michal Bílek , Oliver Müller , Ana Vudragović , Rhys Taylor

Galactic neutral hydrogen (HI) within a few hundred parsecs of the Sun contains structure with an angular distribution that is similar to small-scale structure observed by the Wilkinson Microwave Anisotropy Probe (WMAP). A total of 108…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 Gerrit L. Verschuur

In this contribution, we present some preliminary observational results from the completed ultra-deep survey of 21cm emission from neutral hydrogen at redshifts z=0.164-0.224 with the Westerbork Synthesis Radio Telescope. In two separate…

So far, GJ 710 is the only known star supposed to pass through outskirts of the solar system within 1 ly. We have reexamined the SIMBAD database for additional stellar candidates (from highest ratios of squared parallax to total proper…

Solar and Stellar Astrophysics · Physics 2010-03-30 Igor Yu. Potemine
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