scholarly journals HI shells in the Leiden/Argentina/Bonn HI survey

2013 ◽  
Vol 550 ◽  
pp. A23 ◽  
Author(s):  
S. Ehlerová ◽  
J. Palouš
Keyword(s):  
Hi Shells

scholarly journals The Magnetic Field Near the Local Bubble

1997 ◽  
Vol 166 ◽  
pp. 227-238
Author(s):  
Carl Heiles
Keyword(s):  
Magnetic Field ◽  
Large Scale ◽  
Zeeman Splitting ◽  
Relativistic Electrons ◽  
Local Bubble ◽  
Scale Field ◽  
Large Scale Field ◽  
Field Lines ◽  
Hi Shells ◽  
The Magnetic Field

AbstractThere are almost no direct observational indicators of the magnetic field inside the local bubble. Just outside the bubble, the best tracers are stellar polarization and HI Zeeman splitting. These show that the local field does not follow the large-scale Galactic field. Here we discuss whether the deformation of the large-scale field by the local HI shells is consistent with the observations. We concentrate on the Loop 1 region, and find that the field lines are well-explained by this idea; in addition, the bright radio filaments of Radio Loop 1 delineate particular field lines that are “lit up” by an excess of relativistic electrons.

scholarly journals Study of HI and Star Formation Sites in the Magellanic Bridge

2004 ◽  
Vol 217 ◽  
pp. 506-508 ◽  
Author(s):  
Erik Muller ◽  
Lister Staveley-Smith ◽  
William Zealey
Keyword(s):  
Star Formation ◽  
Spatial Correlation ◽  
Spatial Scales ◽  
Neutral Hydrogen ◽  
Important Process ◽  
Ob Associations ◽  
Active Processes ◽  
Hi Shells

Tidal features represent an important process for the recycling of matter across extremely large spatial scales. The Magellanic Bridge is the closest gaseous tidal feature to our own Galaxy, and offers an ideal opportunity to study the active processes in such phenomena at high spatial resolutions otherwise unavailable. The neutral hydrogen of the western Magellanic Bridge, has been observed with both the Parkes 64m telescope and ATCA interferometer and the resulting dataset has revealed an extremely complex and chaotic morphology. We discuss these observations here with reference to a variety of analyses: the spatial correlation of apparently expanding HI shells with OB associations and the outcome of sensitive Hα and CO surveys.

scholarly journals VLA HI Imaging of the Low Surface Brightness Dwarf Galaxy DDO 47

1999 ◽  
Vol 171 ◽  
pp. 224-227 ◽  
Author(s):  
F. Walter ◽  
E. Brinks
Keyword(s):  
Surface Brightness ◽  
Dwarf Galaxy ◽  
Dynamical Analysis ◽  
Stellar Winds ◽  
Mass Model ◽  
Dynamical Mass ◽  
Systemic Velocity ◽  
Low Surface Brightness ◽  
Simple Mass ◽  
Hi Shells

AbstractWe present high resolution VLA-observations of the nearby Low Surface Brightness Dwarf Galaxy DDO 47. This object shows many hole-like structures in its neutral interstellar medium. The majority of the detected H I-shells are found to be expanding. Their origin is therefore believed to be due to stellar winds of the most massive stars and their subsequent supernova (SN type II) explosions within regions of recent star formation (SF). Current SF in DDO 47 is predominantly present on the rims of the HI-shells suggesting propagating SF. At a projected distance of 20 kpc (adopting a distance to DDO 47 of 4 Mpc), a companion galaxy was detected at almost the same systemic velocity (DDO 47 B). A search for an optical identification suggests that CGCG 087-033 is the optical counterpart of the companion. A preliminary dynamical analysis based on DDO 47’s rotation curve yields that it is dark matter dominated (about 80% of its dynamical mass is in some non-visible form). A simple mass model suggests that DDO 47 is one of the ‘thickest’ dwarf galaxies studied so far.

scholarly journals An automatic identification of HI shells in the 2nd and 3rd Galactic Quadrants

2006 ◽  
Vol 2 (S237) ◽  
pp. 91-95
Author(s):  
Soňa Ehlerová
Keyword(s):  
Size Distribution ◽  
Power Law ◽  
Radial Distribution ◽  
Milky Way ◽  
Hii Regions ◽  
Automatic Identification ◽  
Automatic Method ◽  
Hi Shells ◽  
Scale Length

AbstractWe briefly discuss different methods used to identify HI shells in TB datacubes. Then we give results for our automatic method applied to LDS and LAB HI surveys of the Milky Way (2nd and 3rd quadrants). We fit the radial distribution of HI shells (the exponential profile with the scale length of 3 kpc) and the size distribution (the power law with the index of 2.1). We compare the distribution of identified HI shells with HII regions and study the differences between identifications in the 2nd and 3rd quadrants.

scholarly journals Fast-Expanding Hi Shells Associated with Supernova Remnants in the I-GALFA Survey

2013 ◽  
Vol 9 (S296) ◽  
pp. 386-387
Author(s):  
Geumsook Park ◽  
Bon-Chul Koo ◽  
Steven J. Gibson ◽  
Ji-hyun Kang
Keyword(s):  
Physical Properties ◽  
Survey Data ◽  
Supernova Remnants ◽  
Good Sensitivity ◽  
Velocity Range ◽  
Statistical Nature ◽  
Low Resolution ◽  
Excess Emission ◽  
L Band ◽  
Hi Shells

AbstractWe examine excess emission at high positive and negative velocities toward known Galactic supernova remnants (SNRs) in the “Inner-Galaxy Arecibo L-band Feed Array (I-GALFA)” Hi 21-cm survey data. The I-GALFA survey covers ℓ = 32° to 77°, and has a velocity range of ±700 km s−1 with high angular and velocity resolutions (4′ and 0.18 km s−1, respectively) and good sensitivity (0.2 K). The excess emission which is thought to be part of a fast-expanding Hi shell of a SNR is detected from four among 39 SNRs in the I-GALFA area: W44, G54.4–0.3, W51C, and CTB 80. Although the Hi shells of the four SNRs were already reported in low-resolution studies, the first detection of both sides of an expanding Hi shell associated with W44 is very inspiring. We discuss physical properties of these four SNRs and their statistical nature.

scholarly journals A new class of extraordinary HI shell

1979 ◽  
Vol 84 ◽  
pp. 301-305
Author(s):  
Carl Heiles
Keyword(s):  
Galactic Plane ◽  
Galactic Rotation ◽  
New Class ◽  
Background Gas ◽  
Hi Shells ◽  
Ordinary Means

I consider an ordinary shell to be one which can be produced by ordinary means such as a supernova. Good examples are the HI shells associated with the prominent radio loops, discussed today by Prof. Weaver, and the large HI shell in Eridanus (Heiles, 1976). Figure 1 shows the shell which is associated with radio Loop I, made from a consolidation of data from Martha Cleary of Australia, Raul Colomb and Wolfgang Poppel of Argentina, and myself. It changes size with velocity in the manner expected for an expanding shell. The distance is only 100 pc or so. Similar shells should be easily resolvable in the galactic plane, even with a modest telescope, because differential galactic rotation eliminates the confusing effects of foreground and background gas.

scholarly journals Evidence for triggered star formation in the Carina Flare supershell

2006 ◽  
Vol 2 (S237) ◽  
pp. 406-406 ◽  
Author(s):  
Joanne Dawson ◽  
A. Kawamura ◽  
N. Mizuno ◽  
T. Onishi ◽  
Y. Fukui
Keyword(s):  
Molecular Clouds ◽  
Large Scale ◽  
Mass Star ◽  
Intermediate Mass ◽  
Star Forming ◽  
Star Forming Regions ◽  
Active Intermediate ◽  
Ambient Gas ◽  
Hi Shells ◽  
Intermediate Mass Star

AbstractTheory predicts the triggered formation of molecular clouds stars through the fragmentation and collapse of swept-up ambient gas. Yet the majority of Galactic HI shells show no more than a scattering of small molecular clouds. The Carina Flare supershell (Fukui et al. 1999) is a rare example of an HI shell with a striking molecular component. Here we present the large-scale morphology of the molecular and atomic gas and the location of YSO candidates. A detailed look at two molecular clumps in the shell walls reveals active, intermediate mass star forming regions at various stages of early evolution.

scholarly journals HI Supergiant Shells in the Large Magellanic Cloud

1998 ◽  
Vol 15 (1) ◽  
pp. 132-135 ◽  
Author(s):  
S. Kim ◽  
L. Staveley-Smith ◽  
R. J. Sault ◽  
M. J. Kesteven ◽  
D. McConnell ◽  
...  
Keyword(s):  
Interstellar Medium ◽  
Complex Structure ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Camera Lens ◽  
Hi Shells

AbstractThe recently completed HI mosaic survey of the Large Magellanic Cloud (Kim et al. 1997) reveals complex structure in the interstellar medium, including filaments, arcs, holes and shells. We have catalogued giant and supergiant HI shells and searched for correlations with Hα emission, using a new image taken with a camera lens mounted on the 16-inch telescope at Siding Spring Observatory.

scholarly journals Discussion following Mezger's Report

1970 ◽  
Vol 39 ◽  
pp. 347-361
Author(s):  
I. S. Shklovskii
Keyword(s):  
Star Formation ◽  
Dust Cloud ◽  
Hii Regions ◽  
Recombination Line ◽  
Hi Shells

The Discussion has been rearranged into five sections: 1. Density Concentrations, Cocoon Stars, and OH Sources; 2. The Carbon Recombination Line; 3. The He/H Abundance; 4. Various Shorter Comments; 5. A New Mechanism for Star Formation. A part of the Discussion which related to Spiegel's Report has been transferred to Chapter 13. A short exchange on Hi shells around Hii regions has been deleted and added to Chapter 5. A short part on the dust cloud in Orion at the end of Section 4 has been transferred from Tuesday, September 16.

scholarly journals Hi Shells and Supershells

1983 ◽  
Vol 101 ◽  
pp. 367-372
Author(s):  
Carl Heiles
Keyword(s):  
Angular Resolution ◽  
Galactic Plane ◽  
The North ◽  
Hi Shells

The entire sky has now been surveyed in the 21-cm line with an angular resolution of about 0.5 degree. In the north, above declination −20° or so, the “galactic plane” |b|<10° has been completely sampled Weaver and Williams (1973; 1974). Above declination −30° or so, the sky outside the galactic plane has been almost completely sampled (Heiles and Habing, 1974; Heiles, 1975).

Sign in / Sign up

Export Citation Format

Share Document