scholarly journals Virgo Cluster Early?Type Dwarf Galaxies with the Sloan Digital Sky Survey. II. Early?Type Dwarfs with Central Star Formation

2006 ◽  
Vol 132 (6) ◽  
pp. 2432-2452 ◽  
Author(s):  
Thorsten Lisker ◽  
Katharina Glatt ◽  
Pieter Westera ◽  
Eva K. Grebel
Keyword(s):  
Star Formation ◽  
Dwarf Galaxies ◽  
Central Star ◽  
Virgo Cluster ◽  
Sloan Digital Sky Survey ◽  
Early Type ◽  
Sky Survey

scholarly journals Virgo Cluster Early‐Type Dwarf Galaxies with the Sloan Digital Sky Survey. III. Subpopulations: Distributions, Shapes, Origins

2007 ◽  
Vol 660 (2) ◽  
pp. 1186-1197 ◽  
Author(s):  
Thorsten Lisker ◽  
Eva K. Grebel ◽  
Bruno Binggeli ◽  
Katharina Glatt
Keyword(s):  
Dwarf Galaxies ◽  
Virgo Cluster ◽  
Sloan Digital Sky Survey ◽  
Early Type ◽  
Sky Survey

scholarly journals Star formation in low-redshift cluster dwarf galaxies

2020 ◽  
Vol 493 (4) ◽  
pp. 5625-5635
Author(s):  
Cody M Rude ◽  
Madina R Sultanova ◽  
Gihan L Ipita Kaduwa Gamage ◽  
Wayne A Barkhouse ◽  
Sandanuwan P Kalawila Vithanage
Keyword(s):  
Star Formation ◽  
Dwarf Galaxies ◽  
Sloan Digital Sky Survey ◽  
Galaxy Interactions ◽  
Cluster Data ◽  
Luminosity Functions ◽  
Sky Survey ◽  
Ram Pressure ◽  
Low Mass ◽  
Central Concentration

ABSTRACT Evolution of galaxies in dense environments can be affected by close encounters with neighbouring galaxies and interactions with the intracluster medium. Dwarf galaxies (dGs) are important as their low mass makes them more susceptible to these effects than giant systems. Combined luminosity functions (LFs) in the r and u band of 15 galaxy clusters were constructed using archival data from the Canada–France–Hawaii Telescope. LFs were measured as a function of clustercentric radius from stacked cluster data. Marginal evidence was found for an increase in the faint-end slope of the u-band LF relative to the r-band with increasing clustercentric radius. The dwarf-to-giant ratio (DGR) was found to increase toward the cluster outskirts, with the u-band DGR increasing faster with clustercentric radius compared to the r-band. The dG blue fraction was found to be ∼2 times larger than the giant galaxy blue fraction over all clustercentric distance (∼5σ level). The central concentration (C) was used as a proxy to distinguish nucleated versus non-nucleated dGs. The ratio of high-C to low-C dGs was found to be ∼2 times greater in the inner cluster region compared to the outskirts (2.8σ level). The faint-end slope of the r-band LF for the cluster outskirts (0.6 ≤ r/r200 < 1.0) is steeper than the Sloan Digital Sky Survey field LF, while the u-band LF is marginally steeper at the 2.5σ level. Decrease in the faint-end slope of the r- and u-band cluster LFs towards the cluster centre is consistent with quenching of star formation via ram pressure stripping and galaxy–galaxy interactions.

scholarly journals Comparison of Composite and Star-forming Early-type Galaxies

2021 ◽  
Vol 163 (1) ◽  
pp. 28
Author(s):  
Yu-Zhong Wu
Keyword(s):  
Star Formation ◽  
Stellar Mass ◽  
Sloan Digital Sky Survey ◽  
Early Type ◽  
Massive Galaxies ◽  
Star Forming ◽  
Sky Survey ◽  
Excitation Mechanisms ◽  
Stellar Masses ◽  
Evolution Scheme

Abstract I assemble 4684 star-forming early-type galaxies (ETGs) and 2011 composite ETGs (located in the composite region on the BPT diagram) from the catalog of the Sloan Digital Sky Survey Data Release 7 MPA-JHU emission-line measurements. I compare the properties of both ETG samples and investigate their compositions, stellar masses, specific star formation rates (sSFRs), and excitation mechanisms. Compared with star-forming ETGs, composite ETGs have higher stellar mass and lower sSFR. In the stellar mass and u − r color diagram, more than 60% of star-forming ETGs and composite ETGs are located in the green valley, showing that the two ETG samples may have experienced star formation and that ∼17% of star-forming ETGs lie in the blue cloud, while ∼30% of composite ETGs lie in the red sequence. In the [N II]/Hα versus EWHα (the Hα equivalent width) diagram, all star-forming ETGs and most of the composite ETGs are located in the star-forming galaxy region, and composite ETGs have lower EWHα than their counterparts. We show the relations between 12+log(O/H) and log(N/O) for both ETG samples, and suggest that nitrogen production of some star-forming ETGs can be explained by the evolution scheme of Coziol et al., while the prodution of composite ETGs may be a consequence of the inflowing of metal-poor gas and these more evolved massive galaxies.

scholarly journals The Last Stages of Star Formation in dEs?

2006 ◽  
Vol 2 (S235) ◽  
pp. 317-317
Author(s):  
T. Lisker ◽  
K. Glatt ◽  
P. Westera ◽  
E. K. Grebel
Keyword(s):  
Spectral Analysis ◽  
Star Formation ◽  
Dwarf Galaxies ◽  
Stellar Mass ◽  
Virgo Cluster ◽  
Significant Fraction ◽  
Early Type ◽  
Late Type ◽  
Morphological Transformation

AbstractA significant fraction of Virgo cluster early-type dwarf galaxies have blue central colours caused by recent or ongoing star formation. A spectral analysis shows that even in their centers, stellar mass is dominated by an old population. These galaxies are an unrelaxed cluster population that possibly formed from morphological transformation of late-type galaxies.

Isolated groups of extremely blue dwarf galaxies

2020 ◽  
Vol 15 (S359) ◽  
pp. 168-169
Author(s):  
Vitor Bootz ◽  
Marina Trevisan ◽  
Trinh Thuan ◽  
Yuri Izotov ◽  
Angela Krabbe ◽  
...  
Keyword(s):  
Star Formation ◽  
Dwarf Galaxies ◽  
Statistical Tests ◽  
Formation Rate ◽  
Sloan Digital Sky Survey ◽  
Tidal Forces ◽  
Star Formation Activity ◽  
Sky Survey ◽  
Blue Galaxies ◽  
Very High

AbstractInteractions and mergers between dwarf galaxies are mostly gas-rich and should be marked by an intense star formation activity. But these processes, which are expected to be common at earlier times, are very difficult to observe at low redshifts. To investigate that, we look in the Sloan Digital Sky Survey (SDSS) for compact groups that contain one luminous compact galaxy (LCG) with very high specific star formation rate (sSFR) and at least two other blue galaxies. We found 24 groups that satisfy these criteria, among which 12 groups have SDSS spectroscopic data for at least 2 member galaxies. Here we want to investigate, using the tidal strength estimator Q, how interactions between neighbouring galaxies affect the sSFR and concentration of each LCG. Statistical tests reveal a correlation between Q and their sSFR, indicating that tidal forces between neighbouring galaxies might be inducing bursts of star formation in the LCGs.

scholarly journals Virgo Early-Type Dwarfs in ALFALFA

2007 ◽  
Vol 3 (S244) ◽  
pp. 364-365
Author(s):  
Rebecca A. Koopmann
Keyword(s):  
Star Formation ◽  
Environmental Effects ◽  
Dwarf Galaxies ◽  
Virgo Cluster ◽  
Morphological Transition ◽  
Early Type ◽  
Show Evidence

AbstractEarly-type dwarf galaxies dominate cluster populations, but their formation and evolutionary histories are poorly understood. The ALFALFA (Arecibo Legacy Fast ALFA) survey has completed observations of the Virgo Cluster in the declination range of 6 – 16 degrees. Less than 2% of the early-type dwarf population is detected, a significantly lower fraction than reported in previous papers based on more limited samples. In contrast ~30% of the irregular/BCD dwarf population is detected. The detected early-type galaxies tend to be located in the outer regions of the cluster, with a concentration in the direction of the M Cloud. Many show evidence for ongoing/recent star formation. Galaxies such as these may be undergoing morphological transition due to cluster environmental effects.

scholarly journals Origin of Non-axisymmetric Features of Virgo Cluster Early-type Dwarf Galaxies. I. Bar Formation and Recurrent Buckling

2017 ◽  
Vol 839 (1) ◽  
pp. 24 ◽  
Author(s):  
SungWon Kwak ◽  
Woong-Tae Kim ◽  
Soo-Chang Rey ◽  
Suk Kim
Keyword(s):  
Dwarf Galaxies ◽  
Virgo Cluster ◽  
Early Type ◽  
Bar Formation
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