Tracing Rejuvenation Events in Nearby S0 Galaxies

Marino, A.; Bianchi, Luciana; Rampazzo, R.; Thilker, David A.; Annibali, F.; Bressan, A.; Buson, L. M.

doi:10.1088/0004-637x/736/2/154

Cited by 44 publications

(41 citation statements)

References 58 publications

(62 reference statements)

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“…The position of star-forming blue ETGs on the colour-magnitude/colour-stellar mass diagrams has been interpreted as possible migration from the red sequence to the blue cloud after acquiring sufficient fuel for star formation or fading post-starburst galaxies (Kannappan et al 2009;Huertas-Company et al 2010;Thilker et al 2010;Marino et al 2011;Moffett et al 2012;McIntosh et al 2014;Rutkowski et al 2014;Moffett et al 2015;Wong et al 2015). The sample of a few blue ETGs from other studies was found to host a significant amount of molecular gas (∼ 10 7−9 M⊙) with a linear dependence on star formation surface density within the galaxy and a higher molecular gas star formation efficiency than in normal star-forming late-type galaxies (Wei et al 2010;Stark et al 2013).…”

Section: Discussionmentioning

confidence: 99%

Structural analysis of star-forming blue early-type galaxies

George

2017

A&A

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Context. Star-forming blue early-type galaxies at low redshift can give insight to the stellar mass growth of L * elliptical galaxies in the local Universe. Aims. We wish to understand the reason for star formation in these otherwise passively evolving red and dead stellar systems. The fuel for star formation can be acquired through recent accretion events such as mergers or flyby. The signatures of such events should be evident from a structural analysis of the galaxy image. Methods. We carried out structural analysis on SDSS r-band imaging data of 55 star-forming blue elliptical galaxies, derived the structural parameters, analysed the residuals from best-fit to surface brightness distribution, and constructed the galaxy scaling relations. Results. We found that star-forming blue early-type galaxies are bulge-dominated systems with axial ratio > 0.5 and surface brightness profiles fitted by Sersic profiles with index (n) mostly > 2. Twenty-three galaxies are found to have n < 2; these could be hosting a disc component. The residual images of the 32 galaxy surface brightness profile fits show structural features indicative of recent interactions. The star-forming blue elliptical galaxies follow the Kormendy relation and show the characteristics of normal elliptical galaxies as far as structural analysis is concerned. There is a general trend for high-luminosity galaxies to display interaction signatures and high star formation rates. Conclusions. The star-forming population of blue early-type galaxies at low redshifts could be normal ellipticals that might have undergone a recent gas-rich minor merger event. The star formation in these galaxies will shut down once the recently acquired fuel is consumed, following which the galaxy will evolve to a normal early-type galaxy.

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Section: Discussionmentioning

confidence: 99%

Structural analysis of star-forming blue early-type galaxies

George

2017

A&A

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“…There are only very few massive Galactic GCs whose stars display a spread in iron (and/or calcium) abundance, either large (ω Cen, see Johnson & Pilachowski 2010;Marino et al 2011a and references therein; Terzan5, Ferraro et al 2009;Origlia et al 2011) or small (M54, Bellazzini et al 2008;Carretta et al 2010b;M22, see Da Costa et al 2009;Marino et al 2011b and references therein; NGC 2419, Cohen et al 2010;Ibata et al 2011;Cohen & Kirby 2011;NGC 1851, Carretta et al 2011. At present there is no firmly established case for a correlation between iron abundance (or metallicity, in general) and star kinematics in these clusters.…”

Section: Kinematics and Chemical Compositionmentioning

confidence: 99%

Na-O anticorrelation and HB

Bellazzini

Bragaglia

Carretta

et al. 2012

A&A

100

204

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We use accurate radial velocities for 1981 member stars in 20 Galactic globular clusters, collected within our large survey aimed at analyzing the Na-O anti-correlation, to study the internal kinematics of the clusters. We performed the first systematic exploration of the possible connections between cluster kinematics and the multiple populations phenomenon in GCs. We did not find any significant correlation between Na abundance and either velocity dispersion or systemic rotation. We searched for systemic rotation in the eight clusters of our sample that lack this analysis from previous works in the literature (NGC 2808, NGC 5904, NGC 6171, NGC 6254, NGC 6397, NGC 6388, NGC 6441, and NGC 6838). These clusters are found to span a wide range of rotational amplitudes from ∼0.0 km s −1 (NGC 6397) to ∼13.0 km s −1 (NGC 6441). We found a significant correlation between the ratio of rotational velocity to central velocity dispersion (V rot /σ 0 ) and the horizontal branch morphology parameter (B − R)/(B + R + V). The ratio V rot /σ 0 is found to correlate also with metallicity, possibly hinting at a significant role for dissipation in the process of formation of globular clusters; V rot is found to correlate well with (B − R)/(B + R + V), M V , σ 0 , and [Fe/H]. All these correlations strongly suggest that systemic rotation may be intimately linked with the processes that led to the formation of globular clusters and the stellar populations they host.

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“…We compute FUV, NUV and optical magnitudes of the outer ring structures using surface brightness profiles after subtracting the galaxy contribution as described by Marino et al (2010b). About 25%, 71%, 30%, 33% and 60% of the total FUV luminosity of NGC 1533, NGC 2962, NGC 2974, NGC 4245, NGC 5636 comes from the ring structure.…”

Section: Observationsmentioning

confidence: 99%

“…For the ring structures we derive very young ages ( 200 Myr) adopting a Single Stellar population (SSP), and ∼ 1 Gyr with an Elliptical SFH while assuming Spiral SFH ages are between 2 and 4 Gyr. The stellar mass of the outer rings is about 1-4%, 1%, 1% and 5-8% of the total stellar mass of NGC 1533, NGC 2962, NGC 2974, NGC 4245, NGC 5636, respectively (details are provided in Marino et al 2010b).…”

Section: Characterizing the Star Formation Historymentioning

confidence: 99%

Signatures of recent star formation in ring S0 galaxies

Marino

Bianchi

Rampazzo

et al. 2011

Astrophys Space Sci

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We present a study of the stellar populations of ring and/or arm-like structures in a sample of S0 galaxies using GALEX far-and near-ultraviolet imaging and SDSS optical data. Such structures are prominent in the UV and reveal recent star formation. We quantitatively characterize these rejuvenation events, estimating the average age and stellar mass of the ring structures, as well as of the entire galaxy. The mass fraction of the UV−bright rings is a few percent of the total galaxy mass, although the UV ring luminosity reaches 70% of the galaxy luminosity. The integrated colors of these S0s locates them in the red sequence (NGC 2962) and in the so-called green valley. We suggest that the star formation episodes may be induced by different triggering mechanisms, such as the inner secular evolution driven by bars, and interaction episodes.

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Tracing Rejuvenation Events in Nearby S0 Galaxies

Cited by 44 publications

References 58 publications

Structural analysis of star-forming blue early-type galaxies

Structural analysis of star-forming blue early-type galaxies

Na-O anticorrelation and HB

Signatures of recent star formation in ring S0 galaxies

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