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                    Region Oxygen Abundances in Starbursting Transition Dwarf Galaxies

Dellenbusch, Kate E.; Gallagher, John S.; Knezek, Patricia

doi:10.1086/511678

Cited by 15 publications

(25 citation statements)

References 28 publications

(44 reference statements)

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“…In some cases the gas kinematics are not regular; e.g., Lake et al note the H i in the outer parts of NGC 3265 has confused kinematics, which they summarize as "infall, outflow, no-flow." Lake et al and Sadler et al consider that some of the H i could have been recently accreted, but this now seems unlikely given the high gas phase chemical abundances that we find in Dellenbusch et al (2007).…”

Section: Internal Chemo-dynamical Star-formation Regulationmentioning

confidence: 56%

“…On the other hand, the Virgo Cluster of galaxies appears to contain a complete sequence of more luminous dwarfs with declining and increasingly concentrated star formation, extending from typical BCDs through to blue core dEs (Gallagher & Hunter 1989;Lisker et al 2006Lisker et al , 2007. While moderate luminosity galaxies with early-type outer structures and young stellar populations in their centers also exist in less dense environments (e.g., NGC 404, del Rio et al 2004;NGC 5102, Deharveng et al 1997), they are sufficiently rare that it is difficult to determine if evolutionary sequences exist.…”

Section: Introductionmentioning

confidence: 99%

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Deep Optical Imaging of Starbursting “Transition” Dwarf Galaxies

Dellenbusch

Gallagher

Knezek³

et al. 2007

The Astronomical Journal

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A subgroup of dwarf galaxies have characteristics of a possible evolutionary transition between star-forming systems and dwarf ellipticals. These systems host significant starbursts in combination with smooth, elliptical outer envelopes, and small H i content; they are low on gas and unlikely to sustain high star-formation rates over significant cosmic time spans. We explore possible origins of such starburst "transition" dwarfs using moderately deep optical images. While galaxy-galaxy interactions could produce these galaxies, no optical evidence exists for tidal debris or other outer disturbances, and they also lack nearby giant neighbors which could supply recent perturbations. Colors of the outer regions indicate that star formation ceased >1 Gyr in the past, a longer time span than can be reasonably associated with the current starbursts. We consider mechanisms where the starbursts are tied either to interactions with other dwarfs or to the state of the interstellar medium, and discuss the possibility of episodic star-formation events associated with gas heating and cooling in low specific angular-momentum galaxies.

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Section: Internal Chemo-dynamical Star-formation Regulationmentioning

confidence: 56%

Section: Introductionmentioning

confidence: 99%

Deep Optical Imaging of Starbursting “Transition” Dwarf Galaxies

Dellenbusch

Gallagher

Knezek³

et al. 2007

The Astronomical Journal

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“…In this respect, BCDs are particularly Appendices are available in electronic form at http://www.aanda.org interesting as the burst durations are typically of a few 100 Myr (McQuinn et al 2010a), thus they must evolve into another type of dwarf as the starburst fades. The possibility of morphological transformations between low-mass galaxies is also suggested by the existence of "transition type" dwarfs, which have intermediate properties between Sphs and Irrs/BCDs (e.g., Sandage & Hoffman 1991;Mateo 1998;Dellenbusch et al 2007Dellenbusch et al , 2008.…”

Section: Introductionmentioning

confidence: 99%

Evolution of dwarf galaxies: a dynamical perspective

Lelli

Fraternali

Verheijen

2014

A&A

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For a rotating galaxy, the inner circular-velocity gradient d R V(0) provides a direct estimate of the central dynamical mass density, including gas, stars, and dark matter. We consider 60 low-mass galaxies with high-quality H I and/or stellar rotation curves (including starbursting dwarfs, irregulars, and spheroidals), and estimatewhere R d is the galaxy scale length. For gas-rich dwarfs, we find that V R d /R d correlates with the central surface brightness μ 0 , the mean atomic gas surface density Σ gas , and the star formation rate surface density Σ SFR . Starbursting galaxies, such as blue compact dwarfs (BCDs), generally have higher values of V R d /R d than dwarf irregulars, suggesting that the starburst is closely related to the inner shape of the potential well. There are, however, some "compact" irregulars with values of V R d /R d similar to BCDs. Unless a redistribution of mass takes place, BCDs must evolve into compact irregulars. Rotating spheroidals in the Virgo cluster follow the same correlation between V R d /R d and μ 0 as gasrich dwarfs. They have values of V R d /R d comparable to those of BCDs and compact irregulars, pointing to evolutionary links between these types of dwarfs. Finally, we find that, as for spiral galaxies and massive starbursts, the star-formation activity in dwarfs can be parametrized as Σ SFR = Σ gas /τ orb , where τ orb is the orbital time and 0.02.

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“…Significant constraints to such models could only be provided with a better understanding of dE formation. In contrast to giant ellipticals, formation mechanisms proposed for dEs in clusters are typically not based on an early formation epoch, but rather on infall and subsequent transformation of late-type galaxies through gas-stripping and tidally enhanced star formation (e.g., Davies & Phillipps 1988;Moore et al 1996;van Zee et al 2004;Sabatini et al 2005;Dellenbusch et al 2007). …”

Section: Introductionmentioning

confidence: 99%

Virgo Cluster Early-Type Dwarf Galaxies With the Sloan Digital Sky Survey. Iv. The Color-Magnitude Relation

Lisker

Grebel

Binggeli

2007

The Astronomical Journal

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We present an analysis of the optical colors of 413 Virgo cluster early-type dwarf galaxies (dEs), based on Sloan Digital Sky Survey imaging data. Our study comprises (1) a comparison of the color-magnitude relation (CMR) of the different dE subclasses that we identified in paper III of this series, (2) a comparison of the shape of the CMR in low-and high-density regions, (3) an analysis of the scatter of the CMR, and (4) an interpretation of the observed colors with ages and metallicities from population synthesis models. We find that the CMRs of nucleated (dE(N)) and non-nucleated (dE(nN)) dEs are significantly different from each other, with similar colors at fainter magnitudes (m r 17 mag), but increasingly redder colors of the dE(N)s at brighter magnitudes. We interpret this with older ages and/or higher metallicities of the brighter dE(N)s. The dEs with disk features have similar colors as the dE(N)s and seem to be only slightly younger and/or less metal-rich on average. Furthermore, we find a small but significant dependence of the CMR on local projected galaxy number density, consistently seen in all of u − r, g − r, and g − i, and weakly i − z. We deduce that a significant intrinsic color scatter of the CMR is present, even when allowing for a distance spread of our galaxies. No increase of the CMR scatter at fainter magnitudes is observed down to m r ≈ 17 mag (M r ≈ −14 mag). The color residuals, i.e. the offsets of the data points from the linear fit to the CMR, are clearly correlated with each other in all colors for the dE(N)s and for the full dE sample, implying that, at a given magnitude, a galaxy with an older stellar population than average typically also exhibits a higher metallicity than average. Given the observational data for Virgo dEs presented here and in the previous papers of this series, we conclude that there must be at least two different formation channels for early-type dwarfs in order to explain the heterogeneity of this class of galaxy.

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H ii Region Oxygen Abundances in Starbursting Transition Dwarf Galaxies

Cited by 15 publications

References 28 publications

Deep Optical Imaging of Starbursting “Transition” Dwarf Galaxies

Deep Optical Imaging of Starbursting “Transition” Dwarf Galaxies

Evolution of dwarf galaxies: a dynamical perspective

Virgo Cluster Early-Type Dwarf Galaxies With the Sloan Digital Sky Survey. Iv. The Color-Magnitude Relation

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