A Comparative Study of Star Formation Thresholds in Gas-Rich Low Surface Brightness Dwarf Galaxies

1997 ◽  
Vol 113 ◽  
pp. 1618 ◽  
Author(s):  
Liese van Zee ◽  
Martha P. Haynes ◽  
John J. Salzer ◽  
Adrick H. Broeils
Keyword(s):  
Star Formation ◽  
Comparative Study ◽  
Surface Brightness ◽  
Dwarf Galaxies ◽  
Low Surface Brightness

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.

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.

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 Dwarf Galaxies as Low Surface Brightness Galaxies

1999 ◽  
Vol 171 ◽  
pp. 169-176
Author(s):  
Evan D. Skillman
Keyword(s):  
Star Formation ◽  
Surface Density ◽  
Surface Brightness ◽  
Dwarf Galaxies ◽  
Lower Surface ◽  
Current Evidence ◽  
Chemical Abundance ◽  
Galaxy Surveys ◽  
Low Surface Brightness ◽  
Lsb Galaxies

AbstractBecause of the weak correlation between surface brightness and luminosity, as galaxy surveys reach to lower surface brightnesses, increasing numbers of dwarf galaxies are found. Thus, studies of dwarf galaxies are relevant to our understanding of the low surface brightness universe. In particular, studies of nearby LSB dwarfs may help to answer questions concerning: (1) star formation in low abundance and low mass surface density envrionments, (2) star formation histories of galaxies and the relative youth of LSB galaxies, and (3) the chemical evolution of LSB galaxies. HST WFPC2 photometry of the resolved stars in nearby dwarf galaxies is particularly useful for all three questions.H II region abundances remain the best probe of current ISM abundances. Current evidence favors total mass (or luminosity) as the primary factor for determining the present day chemical abundance in both LSB and HSB galaxies. It remains possible that mass surface density (or surface brightness) may be a second controlling parameter.

scholarly journals The Halos and Environments of Nearby Galaxies (HERON) Survey

2016 ◽  
Vol 11 (S321) ◽  
pp. 186-189 ◽  
Author(s):  
R. Michael Rich ◽  
Noah Brosch ◽  
James Bullock ◽  
Andreas Burkert ◽  
Michelle Collins ◽  
...  
Keyword(s):  
Star Formation ◽  
Surface Brightness ◽  
Spiral Galaxies ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
General Survey ◽  
Tidal Disruption ◽  
Local Volume ◽  
Low Surface Brightness ◽  
Nearby Galaxies

AbstractWe have used dedicated 0.7m telescopes in California and Israel to image the halos of ~ 200 galaxies in the Local Volume to 29 mag/sq arcsec, the sample mainly drawn from the 2MASS Large Galaxy Atlas (LGA). We supplement the LGA sample with dwarf galaxies and more distant giant ellipticals. Low surface brightness halos exceeding 50 kpc in diameter are found only in galaxies more luminous than L*, and classic interaction signatures are relatively infrequent. Halo diameter is correlated with total galaxy luminosity. Extended low surface brightness halos are present even in galaxies as faint as MV = - 18. Edge-on galaxies with boxy bulges tend to lack extended spheroidal halos, while those with large classical bulges exhibit extended round halos, supporting the notions that boxy or barlike bulges originate from disks. Most face-on spiral galaxies present features that appear to be irregular extensions of spiral arms, although rare cases show smooth boundaries with no sign of star formation. Although we serendipitously discovered a dwarf galaxy undergoing tidal disruption in the halo of NGC 4449, we found no comparable examples in our general survey. A search for similar examples in the Local Volume identified hcc087, a tidally disrupting dwarf galaxy in the Hercules Cluster, but we do not confirm an anomalously large half-light radius reported for the dwarf VCC 1661.

scholarly journals Photometric Structure and Star Formation in Blue Compact Dwarf Galaxies

2006 ◽  
Vol 2 (S235) ◽  
pp. 327-327
Author(s):  
P. Papaderos
Keyword(s):  
Star Formation ◽  
Surface Brightness ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
Star Formation History ◽  
Host Galaxy ◽  
Star Forming ◽  
Formation History ◽  
Low Surface Brightness ◽  
Low Mass

The star-formation history and chemodynamical evolution of Blue Compact Dwarf (BCD) galaxies are central issues in dwarf galaxy research. In spite of being old in their vast majority, BCDs resemble in many aspects unevolved low-mass galaxies in the early universe. They are gas-rich (Hi mass fraction of typically > 30%) and metal-deficient (7.1 $\la$ 12+log(O/H) $\la$ 8.3) extragalactic systems, undergoing intense star-forming (SF) activity within an underlying low-surface brightness (LSB) host galaxy.

scholarly journals Low Surface Brightness Dwarf Galaxies in Nearby Clusters

1999 ◽  
Vol 171 ◽  
pp. 157-159
Author(s):  
Kristin Chiboucas ◽  
Mario Mateo
Keyword(s):  
Galaxy Clusters ◽  
Surface Brightness ◽  
Dwarf Galaxies ◽  
Cluster Galaxy ◽  
V Band ◽  
Luminosity Functions ◽  
Low Surface Brightness ◽  
Initial Results

AbstractWe present initial results of a study of low surface brightness dwarf galaxies within galaxy clusters at z ≤ .03 as part of our program to determine the clustering properties, luminosity functions, and morphologies of dwarf galaxies in a wider range of cluster environments. In addition to deep V-band images covering up to 1 deg2 in each of 13 different clusters, we have obtained velocities from fiber spectroscopy for 235 galaxies in A3526. In A3526, we find a drop in cluster galaxy counts at intermediate magnitudes which is supported by our spectroscopic results.

scholarly journals Low Surface Brightness Galaxies in Deep Surveys

1999 ◽  
Vol 171 ◽  
pp. 76-83
Author(s):  
Henry C. Ferguson
Keyword(s):  
Surface Brightness ◽  
Dwarf Galaxies ◽  
Recent Literature ◽  
Solid Angle ◽  
Large Space ◽  
Space Density ◽  
Faint Galaxy ◽  
Low Surface Brightness ◽  
Low Surface Brightness Galaxies ◽  
Lsb Galaxies

AbstractWe examine the constraints that can be placed on the space density of low-surface-brightness galaxies from deep HST images. Such images, while covering only a small solid angle, provide enough depth and spatial resolution to detect LSB galaxies at moderate redshift and distinguish them from galaxies of higher surface brightness.We consider five simple models of the non-evolving or slowly-evolving population of LSB galaxies, motivated by various discussions in the recent literature. The basic results are (1) models with a large space-density of giant LSB galaxies at moderate redshift do not look like the real world and, (2) models with a large space-density of dwarf LSB galaxies are consistent with HST data (that is, they do not produce more faint LSB galaxies per unit solid angle than are detected at magnitudes I ≳ 23), but these LSB dwarf galaxies do not contribute much to faint galaxy counts unless they formed their stars in a rapid burst.

scholarly journals The Ghosts of Galaxies: Tidal Debris in Clusters

2004 ◽  
Vol 217 ◽  
pp. 70-76
Author(s):  
Michael D. Gregg ◽  
Michael J. West
Keyword(s):  
Globular Clusters ◽  
Surface Brightness ◽  
Large Scale ◽  
Dwarf Galaxies ◽  
Cluster Formation ◽  
X Ray ◽  
Cluster Evolution ◽  
Low Surface Brightness ◽  
Intergalactic Space ◽  
Formation And Evolution

Gravitational interactions in rich clusters can strip material from the outer parts of galaxies or even completely disrupt entire systems, giving rise to large scale, low surface brightness ghostly features stretching across intergalactic space. The nearby Coma and Centaurus clusters both have striking examples of galaxy ghosts, in the form of 100 kpc-long plumes of intergalactic debris. By searching HST archival images, we have found numerous other examples of galaxy ghosts in rich clusters at low redshift, evidence that galaxy destruction and recycling are ubiquitous, important in cluster formation and evolution, and continue to mold clusters at the present epoch. Many ghosts appear in X-ray bright clusters, perhaps signaling a connection with energetic subcluster mergers.The fate of such material has important ramifications for cluster evolution. Our new HST WFPC2 V & I images of a portion of the Centaurus plume reveal that it contains an excess of discrete objects with −12 < MV < −6, consistent with being globular clusters or smaller dwarf galaxies. This tidally liberated material is being recycled directly into the intracluster population of stars, dwarf galaxies, globular clusters, and gas, which may have been built largely from a multitude of similar events over the life of the cluster.

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