The Structure of the Superthin Spiral Galaxy UGC7321

1999 ◽  
Vol 171 ◽  
pp. 207-209
Author(s):  
L.D. Matthews ◽  
J.S. Gallagher ◽  
W. van Driel
Keyword(s):  
Star Formation ◽  
Spiral Galaxy ◽  
Surface Brightness ◽  
Scale Height ◽  
Vertical Scale ◽  
Low Surface Brightness ◽  
Galaxy Disk ◽  
Color Gradients

AbstractUGC 7321 is an edge-on low surface brightness (LSB) spiral galaxy with a number of extraordinary properties. Its vertical scale height (~70 pc) is one of the smallest ever measured for a galaxy disk. Its disk also exhibits strong vertical and radial color gradients. UGC 7321 appears to be an extremely unevolved galaxy in both a dynamical and in a star-formation sense.

scholarly journals Gas-rich LSB Galaxies – Progenitors of Blue Compact Dwarfs?

1999 ◽  
Vol 171 ◽  
pp. 253-260 ◽  
Author(s):  
John J. Salzer ◽  
Stuart A. Norton
Keyword(s):  
Star Formation ◽  
Surface Brightness ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
Mass Density ◽  
Central Mass ◽  
Galaxy Distribution ◽  
Low Surface Brightness ◽  
Central Regions ◽  
Lsb Galaxies

AbstractWe analyze deep CCD images of nearby Blue Compact Dwarf (BCD) galaxies in an attempt to understand the nature of the progenitors which are hosting the current burst of star formation. In particular, we ask whether BCDs are hosted by normal or low-surface-brightness dI galaxies. We conclude that BCDs are in fact hosted by gas-rich galaxies which populate the extreme high-central-mass-density end of the dwarf galaxy distribution. Such galaxies are predisposed to having numerous strong bursts of star formation in their central regions. In this picture, BCDs can only occur in the minority of dwarf galaxies, rather than being a common phase experienced by all gas-rich dwarfs.

scholarly journals Star Formation Thresholds in Low Surface Brightness Dwarf Galaxies

1999 ◽  
Vol 171 ◽  
pp. 274-281
Author(s):  
Liese van Zee
Keyword(s):  
Star Formation ◽  
Comparative Study ◽  
Column Density ◽  
Surface Brightness ◽  
Dwarf Galaxies ◽  
Critical Threshold ◽  
Active Star ◽  
Comparison Sample ◽  
Active Star Formation ◽  
Low Surface Brightness

AbstractThe results of a comparative study of star formation thresholds in gas-rich, low surface brightness, dwarf galaxies are presented. Approximately half the galaxies in the study were “high MH/LB” galaxies, which appear to have inefficient star formation properties. The comparison sample comprised of otherwise “normal” dwarf galaxies, with moderate current star formation rates. In all systems, sites of active star formation were associated with local peaks in the HI column density. For both types of galaxies, the azimuthally averaged gas column density is low. Similar to other LSB systems, the global gas densities are well below the critical threshold for star formation throughout the system. Thus, star formation is inhibited globally, but occurs locally in these gas-rich dwarf galaxies.

The Hi Neighborhoods Around STARBIRDS

2018 ◽  
Vol 14 (S344) ◽  
pp. 280-282
Author(s):  
Megan C. Johnson ◽  
Kristen B. W. McQuinn ◽  
John Cannon ◽  
Charlotte Martinkus ◽  
Evan Skillman ◽  
...  
Keyword(s):  
Star Formation ◽  
Surface Brightness ◽  
Spiral Galaxies ◽  
Dwarf Galaxies ◽  
Neutral Hydrogen ◽  
Tidal Interactions ◽  
Low Surface Brightness ◽  
The Galaxy ◽  
Green Bank Telescope ◽  
Intense Star Formation

AbstractStarbursts are finite periods of intense star formation (SF) that can dramatically impact the evolutionary state of a galaxy. Recent results suggest that starbursts in dwarf galaxies last longer and are distributed over more of the galaxy than previously thought, with star formation efficiencies (SFEs) comparable to spiral galaxies, much higher than those typical of non-bursting dwarfs. This difference might be explainable if the starburst mode is externally triggered by gravitational interactions with other nearby systems. We present new, sensitive neutral hydrogen observations of 18 starburst dwarf galaxies, which are part of the STARburst IRregular Dwarf Survey (STARBIRDS) and each were mapped with the Green Bank Telescope (GBT) and/or Parkes Telescope in order to study the low surface brightness gas distributions, a common tracer for tidal interactions.

scholarly journals On the nature of the peculiar superthin LSB galaxy UGC 12281

2011 ◽  
Vol 7 (S284) ◽  
pp. 138-140
Author(s):  
Philip Günster ◽  
Dominik J. Bomans
Keyword(s):  
Star Formation ◽  
Surface Brightness ◽  
Ionized Gas ◽  
Low Surface Brightness ◽  
Lsb Galaxies

AbstractUGC 12281 has been classified as having a pure disk and being a low surface brightness galaxy (LSBG), thus being an obvious member of the so-called superthin galaxies. At the same time it represents an extremely untypical type of LSBG due to its remarkable amount of current star formation and evidence for extraplanar ionized gas. This makes it become a perfect tool to investigate the triggering of star formation in LSB galaxies, located in an alleged isolated area. By means of deep photometry and long-slit spectroscopy we analyse the Hα halo and verify the existence of a potential dwarf companion which we found on processed SDSS images.

scholarly journals Tidal Remnants and Intergalactic H II Regions

2004 ◽  
Vol 217 ◽  
pp. 486-491 ◽  
Author(s):  
Tom Oosterloo ◽  
Raffaella Morganti ◽  
Elaine M. Sadler ◽  
Annette Ferguson ◽  
Thijs van der Hulst ◽  
...  
Keyword(s):  
Star Formation ◽  
Surface Brightness ◽  
Small Scale ◽  
H Ii Regions ◽  
Tidal Disruption ◽  
Tidal Interactions ◽  
Sky Survey ◽  
Low Surface Brightness ◽  
Intergalactic Space ◽  
Star Formation Regions

We report the discovery of two small intergalactic H II regions in the loose group of galaxies around the field elliptical NGC 1490. The H II regions are located at least 100 kpc from any optical galaxy but are associated with a number of large H I clouds that are lying along an arc 500 kpc in length and that have no optical counterpart on the Digital Sky Survey. The sum of the H I masses of the clouds is almost 1010M⊙ and the largest H I cloud is about 100 kpc in size. Deep optical imaging reveals a very low surface brightness counterpart to this largest H I cloud, making this one of the H I richest optical galaxies known (MHI/LV ~ 200). Spectroscopy of the H II regions indicates that the abundance in these H II regions is only slightly sub-solar, excluding a primordial origin of the H I clouds. The H I clouds are perhaps remnants resulting from the tidal disruption of a reasonably sized galaxy, probably quite some time ago, by the loose group to which NGC 1490 belongs. Alternatively, they are remnants of the merger that created the field elliptical NGC 1490. The isolated H II regions show that star formation on a very small scale can occur in intergalactic space in gas drawn from galaxies by tidal interactions. Many such intergalactic small star formation regions may exist near tidally interacting galaxies.

scholarly journals Molecular Gas and Star-formation in Low Surface Brightness Galaxies

2017 ◽  
Vol 154 (3) ◽  
pp. 116 ◽  
Author(s):  
Tian-Wen Cao ◽  
Hong Wu ◽  
Wei Du ◽  
Feng-Jie Lei ◽  
Ming Zhu ◽  
...  
Keyword(s):  
Star Formation ◽  
Surface Brightness ◽  
Molecular Gas ◽  
Low Surface Brightness ◽  
Low Surface Brightness Galaxies
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