Cool Gas and Massive Stars: The Nuclear Ring in M100

Allard, Emma L.; Peletier, Reynier F.; Knapen, Johan H.

doi:10.1086/498264

Cited by 30 publications

(37 citation statements)

References 23 publications

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“…Abundant star formation occurs within and near the ring, with 2 hot spots at the end of the inner bar. Young stars are formed where the velocity dispersion of the gas is low (Allard et al 2005). At present we are studying the stellar populations of the sample of Sa galaxies of Falcón-Barroso et al (2006) in the same way.…”

Section: Discussionmentioning

confidence: 99%

Stars and gas in the inner parts of galaxies seen in SAURON integral field observations

Peletier

Fathi

Allard

et al. 2007

New Astronomy Reviews

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We give two examples of spiral galaxies that show non-circular gas motions in the inner kiloparsecs, from SAURON integral field spectroscopy. We use harmonic decomposition of the velocity field of the ionized gas to study the underlying mass distribution, employing linear theory. The higher order harmonic terms and the main kinematic features of the observed data are consistent with an analytically constructed simple bar model. We also present maps of a number of strong absorption lines in M 100, derive simple stellar populations and correlate them with features in the gas kinematics.

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Section: Discussionmentioning

confidence: 99%

Stars and gas in the inner parts of galaxies seen in SAURON integral field observations

Peletier

Fathi

Allard

et al. 2007

New Astronomy Reviews

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“…This picture requires that substantial amounts of gas are directed towards the central regions, the gas cools and forms stars. The newly-born stars are thus concentrated toward the centre, and since they are formed from the low-dispersion gas component, their σ is lower than that of the old stellar component (Allard et al 2005;Barbosa et al 2006;Falcón-Barroso et al 2006;Fathi et al 2006). This is quite plausible under the circumstances that gas accumulates in a nuclear disc or a bar, where dissipative cooling can be quite effective in producing the condensation required to form stars.…”

Section: The Innermost Kiloparsecmentioning

confidence: 99%

Evolution of structure in late-type spiral galaxies

Fathi

Beckman

Zurita

et al. 2007

A&A

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Aims. We study two dimensional Fabry-Perot interferometric observations of the nearby face-on late-type spiral galaxy, NGC 628, in order to analyse the ionized gas component of the interstellar medium. Covering the galaxy out to a radius larger than 12 kpc, and with a spatial sampling of 1. 6, we aim to investigate the large-scale dynamics as well as feedback from individual H  regions into their surrounding medium. Methods. The observed Hα emission distribution and kinematics are compared with auxiliary data from molecular and atomic gas observations, which display many similarities. We decompose the observed line-of-sight velocities into rotational and higher-order harmonic components, and study the role of gravitational perturbations along with that of external triggers which can disturb the kinematics and morphology of NGC 628. We calculate radial profiles of the emission-line velocity dispersion which we use to study the role of feedback from individual H  regions.Results. We verify the presence of an inner rapidly rotating disc-like component in NGC 628, which we interpret as caused by slow secular evolution of the large-scale spiral arms and oval structure. In combination with auxiliary data, we find indication for that gas is falling in from the outer parts towards the central regions, where a nuclear ring has formed at the location of the inner Lindblad resonance radius of an an m = 2 perturbation. Complementary continuum subtracted narrow band images in Hα have been used to identify 376 H  regions with calibrated luminosities. The mean velocity dispersion for the ionized gas (even when excluding pixels belonging to H  regions) is almost constant out to 12 kpc, although it varies from 14 to 20 km s −1 , with a steady decline in the outer parts. Conclusions. We have found kinematic signatures of radial motions caused by an m = 2 perturbation. Such a perturbation may well be responsible for the inflow of material forming the nuclear ring and the inner rapidly rotating disc-like structure. The latter, in turn, could help build a pseudo-bulge in NGC 628. The current paper demonstrates a number of tools that we have developed for building a solid frame work for studying the evolution of structure in spiral galaxies using two dimensional kinematic observations.

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“…The stars inherit the velocity pattern of the gas from which they form, so their velocity dispersion is lower than that of the older, 'underlying' stars. A young stellar population dominates an older population in luminosity, so the resulting spectrum is dominated by the lower velocity dispersion of the younger stars (see, e.g., Wozniak et al 2003, also Allard et al 2005Allard et al , 2006. This effect can be enhanced by a falling velocity dispersion of the gas towards the centre of a galaxy, due to a strong accumulation of gas in a dissipative disc that would cool the gas in a cold component (i.e., a cold disc as shown in Falcón-Barroso et al 2006).…”

Section: Introductionmentioning

confidence: 99%

On the morphology of sigma-drop galaxies

Comerón

Knapen

Beckman

2008

A&A

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Context. Local reductions of the stellar velocity dispersion in the central regions of galaxies are known as sigma-drops (σ-drops). Knowing the origin of these features can lead to better understanding of inner galactic dynamics. Aims. We present a sample of 20 σ-drop galaxies matched with a control sample of galaxies without σ-drop in order to search for correlations between σ-drops and the properties, primarily morphological, of the nuclear zones and discs of their host galaxies. Methods. We study the dust and Hα distribution at 0.1 arcsec scale, using Hubble Space Telescope imaging, in the circumnuclear zones of the two samples of galaxies, searching for differences and trying to establish a link between the nuclear kinematics and the host morphology. We have also considered the CO and H i emission of the galaxies and their luminosity profiles.Results. We classify the two samples following both morphological parameters and the luminosity profiles. We find a larger fraction of nuclear dust spirals and Hα rings in the σ-drop sample. We also find that the fraction of Seyfert galaxies in the σ-drop sample is bigger than that of LINERs and that the reverse is true for the control sample. Conclusions. Our findings are evidence that a σ-drop is very probably due to inflow-induced star formation in a dynamically cool disc, or in a gas ring, shock focused by an inner Lindblad resonance above a certain critical density level. The same mechanism that feeds the nuclear ring or the nuclear disc is probably reponsible for the higher rate of Seyfert galaxies among the σ-drop hosts.

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Cool Gas and Massive Stars: The Nuclear Ring in M100

Cited by 30 publications

References 23 publications

Stars and gas in the inner parts of galaxies seen in SAURON integral field observations

Stars and gas in the inner parts of galaxies seen in SAURON integral field observations

Evolution of structure in late-type spiral galaxies

On the morphology of sigma-drop galaxies

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