Related papers: Neutral Hydrogen Clouds in the M81/M82 Group

Neutral hydrogen observations of the nearby, edge-on spiral galaxy NGC 891 reveal the presence of an HI halo extending up to at least 5 kpc from the plane. This halo gas appears to rotate 25 to 100 km/s more slowly than the gas in the…

An extended HI cloud (VIRGOHI 21) with an HI mass of $\sim10^8$ M$_{\odot}$ and no apparent optical counterpart was recently discovered in the Virgo cluster. In order to understand the origin of physical properties of apparently isolated HI…

We present the initial results from an [O III] lambda 5007 survey for intra-group planetary nebulae in the M 81 group of galaxies. A total of 0.36 square degrees of the survey have been analyzed thus far, and a total of four intra-group…

We present HI observations of the galaxies in the first list of the Karachentsev catalog of previously unknown nearby dwarf galaxies (Karachentseva & Karachentsev 1998). This survey covers all known nearby galaxy groups within the Local…

A distinct sub-class of anomalous velocity HI emission features has emerged from recent high quality surveys of the Local Group environment, namely the compact high velocity clouds (CHVCs). A program of high-resolution imaging with the…

We examine the clustering properties of HI-selected galaxies through an analysis of the HI Parkes All-Sky Survey Catalogue (HICAT) two-point correlation function. Various sub-samples are extracted from this catalogue to study the overall…

Studies of the Milky Way's disk-halo interface have historically identified inflowing and outflowing gas incompatible with disk rotation on the basis of radial velocity, leading to the well-known categories of intermediate-velocity clouds…

We present new multi-configuration VLA HI spectral line observations of the M81 group dIrr post-starburst galaxy DDO 165. The HI morphology is complex, with multiple column density peaks surrounding a large region of very low HI surface…

We discuss the possibility of performing blind surveys to detect large-scale features of the universe using 21cm emission. Using instruments with approx. 5'-10' resolution currently in the planning stage, it should be possible to detect…

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)…

Results are presented of the first blind HI survey of the M81 group of galaxies. The data were taken as part of the HI Jodrell All Sky Survey (HIJASS). The survey reveals several new aspects to the complex morphology of the HI distribution…

We present an analysis comparing the properties of 45 giant molecular clouds (GMCs) in M33 and the atomic hydrogen (HI) with which they are associated. High-resolution VLA observations are used to measure the properties of HI in the…

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…

We present the catalog of galaxy groups in the Local Supercluster. Our algorithm bases on assumption that a total energy of physical pair of galaxies must be negative. About 54% of the galaxies in our sample have been gathered in 1082…

A high latitude HI 21 cm-line absorption survey toward extragalactic sources was recently completed using the Giant Meterwave Radio Telescope (GMRT). A total of 104 sources with mod(b) > 15 deg. and with a 21 cm flux density greater than 1…

We report the detection of a largely ionized very-high velocity cloud (VHVC; $v_{\rm LSR}\sim-350$ km/s) toward M33 with the Hubble Space Telescope/Cosmic Origin Spectrograph. The VHVC is detected in OI, CII, SiII, and SiIII absorption…

We report the discovery by the Arecibo Legacy Fast ALFA (ALFALFA) survey of eight HI features not coincident with stellar counterparts in the Virgo Cluster region. All of the HI clouds have cz < 3000 km/s and, if at the Virgo distance, HI…

To determine the relative distances and peculiar velocities of 140 groups and clusters of galaxies at low redshifts ($z$ < 0.12), we used the fundamental plane (FP) of early-type galaxies (from the Sloan Digital Sky Survey (SDSS) data). We…

Atomic hydrogen constitutes the gas reservoir from which molecular gas and star formation in galaxies emerges. However, the weakness of the line means it has been difficult to directly detect in all but the very local Universe. Here we…

Recent spectroscopic observations of intermediate- and high-velocity clouds (IVCs and HVCs) in the Milky Way halo have unveiled the presence of diffuse interstellar molecular hydrogen (H_2) several kpc away from the Galactic disk. Most of…