scholarly journals Star Formation Along the Bars of Virgo Cluster and Isolated Spiral Galaxies

1996 ◽  
Vol 157 ◽  
pp. 105-107
Author(s):  
Rebecca A. Koopmann ◽  
Jeffrey D. P. Kenney
Keyword(s):  
Star Formation ◽  
Spiral Galaxies ◽  
Control Sample ◽  
Virgo Cluster ◽  
Early Type ◽  
Late Type ◽  
Barred Galaxies ◽  
Tidal Interactions ◽  
Isolated Galaxies ◽  
Gradient Measurements

Star formation along the bar is common in late-type barred galaxies (Phillips and Garcia-Barreto et al., these proceedings), which tend to have weak stellar bars. It is rarer in strongly barred galaxies, e.g., early-type spiral galaxies. Abundance gradient measurements (Martin & Roy 1995) and simulations (Friedli & Benz 1995) suggest that star formation along the bar of strongly barred galaxies may indicate a young bar. Since bars can be created in tidal interactions and mergers (Noguchi 1987), it is of interest to investigate the star formation properties of barred galaxies in different environments. We use Hα images to compare the star formation properties in the bar region of a sample of barred galaxies in the Virgo Cluster and a control sample of isolated galaxies. We focus on the three galaxies with the strongest star formation along the bar, including NGC 4424, a possible merger remnant.

scholarly journals Barred Galaxies: Intrinsic or Extrinsic?

1996 ◽  
Vol 157 ◽  
pp. 339-348 ◽  
Author(s):  
M. Noguchi
Keyword(s):  
Simple Model ◽  
Gravitational Instability ◽  
Dynamical Property ◽  
Disk Galaxies ◽  
Early Type ◽  
Late Type ◽  
Galactic Disks ◽  
Barred Galaxies ◽  
Tidal Interactions ◽  
Key Parameter

AbstractA unified picture is presented for the formation of bars in galaxies of different morphological types based on a simple model of the growth of galactic disks by gas infall from haloes. The infall timescale is found to be a key parameter which determines the dynamical property of the resulting disk. It is suggested that the bars in early-type disk galaxies have been formed in tidal interactions with other galaxies whereas those in late-type galaxies formed spontaneously due to gravitational instability (bar instability) in their disks.

scholarly journals Gas Flows in Galaxies: the Relative Importance of Mergers and Bars.

2010 ◽  
Vol 6 (S277) ◽  
pp. 178-181
Author(s):  
Sara L. Ellison ◽  
David R. Patton ◽  
Preethi Nair ◽  
Luc Simard ◽  
J. Trevor Mendel ◽  
...  
Keyword(s):  
Star Formation ◽  
Large Scale ◽  
Formation Rate ◽  
Control Sample ◽  
Central Star ◽  
Sloan Digital Sky Survey ◽  
Galaxy Interactions ◽  
Barred Galaxies ◽  
Isolated Galaxies ◽  
Stellar Masses

AbstractGalaxy-galaxy interactions and large scale galaxy bars are usually considered as the two main mechanisms for driving gas to the centres of galaxies. By using large samples of galaxy pairs and visually classified bars from the Sloan Digital Sky Survey (SDSS), we compare the relative efficiency of gas inflows from these two processes. We use two indicators of gas inflow: star formation rate (SFR) and gas phase metallicity, which are both measured relative to control samples. Whereas the metallicity of galaxy pairs is suppressed relative to its control sample of isolated galaxies, galaxies with bars are metal-rich for their stellar mass by 0.06 dex over all stellar masses. The SFRs of both the close galaxy pairs and the barred galaxies are enhanced by ~60%, but in the bars the enhancement is only seen at stellar masses M∗ > 1010 M⊙. Taking into account the relative frequency of bars and pairs, we estimate that at least three times more central star formation is triggered by bars than by interactions.

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.

scholarly journals Environmental Extremists in the Virgo Cluster

1999 ◽  
Vol 186 ◽  
pp. 387-392 ◽  
Author(s):  
Jeffrey Kenney ◽  
Rebecca Koopmann
Keyword(s):  
Spiral Galaxies ◽  
Rapid Evolution ◽  
Virgo Cluster ◽  
Early Type ◽  
Low Velocity ◽  
Galaxy Interactions ◽  
Cluster Galaxies ◽  
Tidal Interactions ◽  
Environmental Interactions ◽  
Density Relationship

Many types of galaxy interactions have been posited to occur in clusters, although it remains unclear which processes actually occur, and which ones might help explain the tendency for early type galaxies to inhabit high density environments, or cause the rapid evolution of cluster galaxies (e.g., Dressler et al. 1997). With these questions in mind, we have been conducting an environmental inventory of galaxies in the Virgo Cluster. Our approach is to combine surveys of spirals and S0s with detailed studies of the most interesting and peculiar galaxies. In this paper, we describe two main points. 1.) There is a population of spiral galaxies in the Virgo cluster with the small central light concentrations (bulge-to-disk ratios, or B/D's) characteristic of isolated Sb and Sc galaxies, but global star formation rates lower than those of isolated spirals of any Hubble class (Sa-Sc). These Virgo galaxies are generally classified as “early type” (e.g. Sa), and thus contribute to the morphology-density relationship. 2.) There are several types of environmental interactions occurring in Virgo, including low velocity tidal interactions and mergers, high velocity tidal interactions and collisions, HI accretion, and ICM-ISM stripping. We discuss examples of some of these interactions.

scholarly journals Evidence for a Morphological Evolution of Spiral Galaxies

2001 ◽  
Vol 204 ◽  
pp. 387-387
Author(s):  
Yvan Dutil ◽  
Jean-René Roy
Keyword(s):  
Detailed Analysis ◽  
Spiral Galaxies ◽  
Morphological Evolution ◽  
Theoretical Models ◽  
Morphological Type ◽  
Disk Galaxies ◽  
Early Type ◽  
Late Type ◽  
Barred Galaxies ◽  
Abundance Profile

A detailed analysis of the oxygen abundance profile has been carried out on a sample of spiral galaxies from which very good data was available. The early-type galaxies of our sample display gradients that are flatter, and overall levels of O/H abundances that are higher, than those of normal late-type galaxies. Early-type galaxies show an identical trend in the behavior of extrapolated central abundance versus morphological type to that shown by late-type galaxies with strong bars, even in the absence of a bar. On a diagram showing extrapolated central abundances versus morphological types, two clearly separated sequences appear: late-type barred galaxies and early-type (barred or unbarred) galaxies clearly fall on a sequence 0.5 dex in abundance below that of normal late-type galaxies. This behavior is consistent with theoretical models of morphological evolution of disk galaxies by the formation and dissolution of a bar over a period of a few 109 yr, where later type galaxies (Sd, Sc, SBc) evolve into earlier-type disk galaxies (Sb, Sa) through transitory SBc and SBb phases.

scholarly journals Distribution of star formation in galactic bars as seen with Hα and stacked GALEX UV imaging

2020 ◽  
Vol 644 ◽  
pp. A38
Author(s):  
S. Díaz-García ◽  
F. D. Moyano ◽  
S. Comerón ◽  
J. H. Knapen ◽  
H. Salo ◽  
...  
Keyword(s):  
Star Formation ◽  
Gas Flow ◽  
Control Sample ◽  
Morphological Type ◽  
Middle Part ◽  
Disk Galaxies ◽  
Late Type ◽  
Barred Galaxies ◽  
Uv Imaging ◽  
Uv Emission

Context. Stellar bars are known to gradually funnel gas to the central parts of disk galaxies. It remains a matter of debate why the distribution of ionized gas along bars and in the circumnuclear regions varies among galaxies. Aims. Our goal is to investigate the spatial distribution of star formation (SF) within bars of nearby low-inclination disk galaxies (i <  65°) from the S4G survey. We aim to link the loci of SF to global properties of the hosts (morphological type, stellar mass, gas fraction, and bar-induced gravitational torques), providing constraints for the conditions that regulate SF in bars. Methods. We use archival GALEX far- and near-UV imaging for 772 barred galaxies, and for a control sample of 423 non-barred galaxies. We also assemble a compilation of continuum-subtracted Hα images for 433 barred galaxies, 70 of which we produced from ancillary photometry and MUSE and CALIFA integral field unit data cubes. We employ two complementary approaches: (i) the analysis of bar (2D) and disk (1D) stacks built from co-added UV images (oriented and scaled with respect to the stellar bars and the extent of disks) of hundreds of galaxies that are binned based on their Hubble stage (T) and bar family; and (ii) the visual classification of the morphology of ionized regions (traced from Hα and UV data) in individual galaxies into three main SF classes: (A) only circumnuclear SF; (B) SF at the bar ends, but not along the bar; and (C) SF along the bar. Barred galaxies with active and passive inner rings are likewise classified. Results. Massive, gas-poor, lenticular galaxies typically belong to SF class A; this is probably related to bar-induced quenching of SF in the disk. The distribution of SF class B peaks for early- and intermediate-type spirals; this most likely results from the interplay of gas flow, shocks, and enhanced shear in massive centrally concentrated galaxies with large bar amplitudes (the latter is supported by the lack of a dip in the radial distribution of SF in non-barred galaxies). Late-type gas-rich galaxies with high gravitational torques are mainly assigned to SF class C; we argue that this is a consequence of low shear among the faintest galaxies. In bar stacks of spiral galaxies the UV emission traces the stellar bars and dominates on their leading side, as witnessed in simulations. Among early-type spirals the central UV emission is ∼0.5 mag brighter in strongly barred galaxies, relative to their weakly barred counterparts; this is probably related to the efficiency of strong bars sweeping the disk gas and triggering central starbursts. On the contrary, in later types the UV emission is stronger at all radii in strongly barred galaxies than in weakly barred and non-barred ones. We also show that the distributions of SF in inner-ringed galaxies are broadly the same in barred and non-barred galaxies, including a UV and Hα deficit in the middle part of the bar; this hints at the effect of resonance rings trapping gas that is no longer funneled inwards. Conclusions. Distinct distributions of SF within bars are reported in galaxies of different morphological types. Star-forming bars are most common among late-type gas-rich galaxies. Bars are important agents in the regulation of SF in disks.

scholarly journals Dorado and its member galaxies

2020 ◽  
Vol 643 ◽  
pp. A176
Author(s):  
R. Rampazzo ◽  
S. Ciroi ◽  
P. Mazzei ◽  
F. Di Mille ◽  
E. Congiu ◽  
...  
Keyword(s):  
Star Formation ◽  
Spiral Galaxies ◽  
Star Formation Rate ◽  
Large Fraction ◽  
Formation Rate ◽  
Morphological Type ◽  
Gas Content ◽  
Early Type ◽  
Late Type ◽  
Star Formation Activity

Context. Dorado is a nearby, rich and clumpy galaxy group that extends for several degrees in the southern hemisphere. Although several studies have been dedicated to defining its members, their kinematics, and the hot and cold gas content, in particular H I, their present star formation activity remains unknown. Aims. For the first time, we map the Hα distribution as a possible indicator of the star formation activity of Dorado members, a large fraction of which show interaction and merging signatures independently of their morphological type. Methods. With the 2.5 m du Pont and the 1m Swope telescopes, we obtained narrow-band calibrated images of 14 galaxies that form the backbone of the group, mapping Hα+[N II] down to a few 10−17 erg cm−2 s−1 arcsec−2. We estimated the galaxy star formation rate from the Hα fluxes and corrected for Galaxy foreground extinction and [N II] contamination. Results. We detected Hα+[N II] emission in all galaxies. H II regions clearly emerge in late-type galaxies, while in early-type galaxies the Hα+[N II] emission is dominated by [N II], especially in the central regions. However, H II complexes are revealed in four early-type galaxies. Even in the compact group SGC 0414-5559, in the projected centre of Dorado, H II regions are found both throughout the late-type galaxies and in the very outskirts of early-type members. Considering the Dorado group as a whole, we notice that the Hα+[N II] equivalent width, a measure of the specific star formation, increases with morphological type from early- to late-type members, although it remains lower than that observed in similar surveys of spiral galaxies. The star formation rate of the spiral members is in the range of what is observed in similar galaxies surveys (James et al., 2004). However, in three spiral galaxies, NGC 1536, PGC 75125, and IC 2058, the star formation rate is well below the median for their morphological classes. Conversely, the star formation rate of some early-type members tends to be higher than the average derived from Hα+[N II] surveys of this morphological family. Conclusions. We detected Hα+[N II] in all the early-type galaxies observed and half of them show H II regions in well-shaped rings as well as in their outskirts. These findings suggest that early-type galaxies in this group are not dead galaxies: their star formation has not yet shut down. Mechanisms such as gas stripping and gas accretion through galaxy–galaxy interaction seem relevant in modifying star formation in this evolutionary phase of Dorado.

scholarly journals Dawes Review 4: Spiral Structures in Disc Galaxies

2014 ◽  
Vol 31 ◽  
Author(s):  
Clare Dobbs ◽  
Junichi Baba
Keyword(s):  
Star Formation ◽  
Spiral Galaxies ◽  
Fundamental Problem ◽  
Current Status ◽  
Spiral Arms ◽  
Barred Galaxies ◽  
Tidal Interactions ◽  
Star Formation In Galaxies ◽  
1960S And 1970S ◽  
The 1960S

AbstractThe majority of astrophysics involves the study of spiral galaxies, and stars and planets within them, but how spiral arms in galaxies form and evolve is still a fundamental problem. Major progress in this field was made primarily in the 1960s, and early 1970s, but since then there has been no comprehensive update on the state of the field. In this review, we discuss the progress in theory, and in particular numerical calculations, which unlike in the 1960s and 1970s, are now commonplace, as well as recent observational developments. We set out the current status for different scenarios for spiral arm formation, the nature of the spiral arms they induce, and the consequences for gas dynamics and star formation in different types of spiral galaxies. We argue that, with the possible exception of barred galaxies, spiral arms are transient, recurrent and initiated by swing amplified instabilities in the disc. We suppose that unbarredm= 2 spiral patterns are induced by tidal interactions, and slowly wind up over time. However the mechanism for generating spiral structure does not appear to have significant consequences for star formation in galaxies.

scholarly journals Dust properties in the cold and hot gas phases of the ATLAS3D early-type galaxies as revealed by AKARI

2019 ◽  
Vol 622 ◽  
pp. A87 ◽  
Author(s):  
T. Kokusho ◽  
H. Kaneda ◽  
M. Bureau ◽  
T. Suzuki ◽  
K. Murata ◽  
...  
Keyword(s):  
Star Formation ◽  
Virgo Cluster ◽  
Spectral Energy ◽  
X Rays ◽  
Early Type ◽  
Late Type ◽  
X Ray ◽  
Gas Phases ◽  
Hot Gas ◽  
Fast Rotating

Context. The properties of the dust in the cold and hot gas phases of early-type galaxies (ETGs) are key to understanding ETG evolution. Aims. We aim to conduct a systematic study of the dust in a large sample of local ETGs, focusing on relations between the dust and the molecular, atomic, and X-ray gas of the galaxies, as well as their environment. Methods. We estimated the dust temperatures and masses of the 260 ETGs from the ATLAS3D survey, using fits to their spectral energy distributions primarily constructed from AKARI measurements. We also used literature measurements of the cold (CO and H I) and X-ray gas phases. Results. Our ETGs show no correlation between their dust and stellar masses, suggesting inefficient dust production by stars and/or dust destruction in X-ray gas. The global dust-to-gas mass ratios of ETGs are generally lower than those of late-type galaxies, likely due to dust-poor H I envelopes in ETGs. They are also higher in Virgo Cluster ETGs than in group and field ETGs, but the same ratios measured in the central parts of the galaxies only are independent of galaxy environment. Slow-rotating ETGs have systematically lower dust masses than fast-rotating ETGs. The dust masses and X-ray luminosities are correlated in fast-rotating ETGs, whose star formation rates are also correlated with the X-ray luminosities. Conclusions. The correlation between dust and X-rays in fast-rotating ETGs appears to be caused by residual star formation, while slow-rotating ETGs are likely well evolved, and have therefore exhausted their dust. These results appear consistent with the postulated evolution of ETGs, whereby fast-rotating ETGs form by mergers of late-type galaxies and associated bulge growth, while slow-rotating ETGs form by (dry) mergers of fast-rotating ETGs. Central cold dense gas appears to be resilient against ram pressure stripping, suggesting that Virgo Cluster ETGs may not suffer strong related suppression of star formation.

scholarly journals Variations in the 24 μm morphologies of nearby galaxies

2007 ◽  
Vol 3 (S245) ◽  
pp. 121-124
Author(s):  
G. J. Bendo
Keyword(s):  
Star Formation ◽  
Spiral Galaxies ◽  
Dust Emission ◽  
Wave Band ◽  
Morphological Parameters ◽  
Early Type ◽  
Late Type ◽  
The Real ◽  
Hubble Sequence ◽  
Nearby Galaxies

AbstractTo study the distribution of star formation and dust emission within nearby galaxies, we measured five morphological parameters in the 24 μm wave band for 73 galaxies observed as part of the Spitzer Infrared Nearby Galaxies Survey. The morphological parameters demonstrate strong variations along the Hubble sequence, including statistically significant differences between S0/a-Sab and Sc-Sd galaxies. Early-type spiral galaxies are generally found to be compact, centralized, symmetric sources in the 24 μm band, whereas late-type spiral galaxies are generally found to be extended, asymmetric 24 μm sources. These results suggest that processes that increase the real or apparent sizes of galaxies' bulges also lead to more centralized 24 μm emission.

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