How does star formation proceed in the circumnuclear starburst ring of NGC 6951?

Laan, T. P. R. van der; Schinnerer, E.; Emsellem, Éric; Hunt, L. K.; McDermid, Richard M.; Liu, Guilin

doi:10.1051/0004-6361/201220285

Cited by 23 publications

(24 citation statements)

References 43 publications

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“…Nuclear rings in barred-spiral galaxies often exhibit strong activities of star formation (e.g., Buta & Combes 1996;Kenney 1997;Knapen et al 2006;Mazzuca et al 2008Mazzuca et al , 2011Sandstrom et al 2010;Hsieh et al 2011van der Laan et al 2011Onishi et al 2015). They are mostly circular, with ellipticity of e∼0-0.4.…”

Section: Introductionmentioning

confidence: 99%

“…Because star clusters age as they orbit about the galaxy center, the pearls-on-a-string model naturally explains the presence of an azimuthal age gradient, while clusters with different ages are well mixed in the popcorn model (see also, e.g., Ryder et al 2001Ryder et al , 2010Allard et al 2006;Sandstrom et al 2010;van der Laan et al 2013). The most important factor that determines the dominating type of star formation appears to be the mass inflow rateṀ to the ring along the dust lanes (Seo & Kim 2013.…”

Section: Introductionmentioning

confidence: 99%

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Equilibrium Sequences and Gravitational Instability of Rotating Isothermal Rings

Kim

Moon

2016

ApJ

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Nuclear rings at the centers of barred galaxies exhibit strong star formation activities. They are thought to undergo gravitational instability when they are sufficiently massive. We approximate them as rigidly rotating isothermal objects and investigate their gravitational instability. Using a self-consistent field method, we first construct their equilibrium sequences specified by two parameters: α corresponding to the thermal energy relative to gravitational potential energy, and  R B measuring the ellipticity or ring thickness. Unlike in the incompressible case, not all values of  R B yield an isothermal equilibrium, and the range of  R B for such equilibria shrinks with decreasing α. The density distributions in the meridional plane are steeper for smaller α, and well approximated by those of infinite cylinders for slender rings. We also calculate the dispersion relations of non-axisymmetric modes in rigidly rotating slender rings with angular frequency Ω 0 and central density r c . Rings with smaller α are found more unstable with a larger unstable range of the azimuthal mode number. The instability is completely suppressed by rotation when Ω 0 exceeds the critical value. The critical angular frequency is found to be almost constant at ( ) r G 0.7 c 1 2 for α0.01 and increases rapidly for smaller α. We apply our results to a sample of observed star-forming rings and confirm that rings without a noticeable azimuthal age gradient of young star clusters are indeed gravitationally unstable.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Equilibrium Sequences and Gravitational Instability of Rotating Isothermal Rings

Kim

Moon

2016

ApJ

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“…Van der Laan et al (2013) investigated this. The fitting routine minimizes the number of SSP spectra needed to achieve an acceptable fit.…”

Section: Stellar Populations From Sauron Observationsmentioning

confidence: 99%

“…They extracted their fluxes via aperture photometry in the following broadband filters: F220W, F336W, F547M, F814W and F160W. Here, we use a χ 2 fitting routine and Starburst99 models also used in Van der Laan et al (2013) to re-determine the ages, masses and color excess for each star cluster in that set. The parameters of the Starburst99 models are: Starburst99 version v6.0.2 (Leitherer et al 1999;Vázquez & Leitherer 2005;Leitherer et al 2010), run in burst mode, with a Kroupa IMF, solar metallicity, and Padova AGB solar metallicity tracks.…”

Section: Ages Of the Stellar Clusters In The Ringsmentioning

confidence: 99%

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Explaining two circumnuclear star forming rings in NGC 5248

Laan

Schinnerer

Emsellem

et al. 2013

A&A

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The distribution of gas in the central kiloparsec of a galaxy has a dynamically rapid evolution. Nonaxisymmetries in the gravitational potential of the galactic disk, such as a large scale stellar bar or spiral, can lead to significant radial motion of gaseous material from larger radii to the central region. The large influx of gas and the subsequent star formation keep the central region constantly changing. However, the ability of gas to reach the nucleus proper to fuel an AGN phase is not guaranteed. Gas inflow can be halted at a circumnuclear star forming ring several hundred parsec away. The nearby galaxy NGC 5248 is especially interesting in this sense since it is said to host 2 circumnuclear star forming rings at 100 pc and 370 pc from its quiescent nucleus. Here we present new subarcsecond PdBI+30 m CO(2−1) emission line observations of the central region. For the first time the molecular gas distribution at the smallest stellar ring is resolved into a gas ring, consistent with the presence of a quiescent nucleus. However, the molecular gas shows no ring structure at the larger ring. We combine analyses of the gaseous and stellar content in the central kiloparsec of this galaxy to understand the gas distribution and dynamics of this star forming central region. We discuss the probability of two scenarios leading to the current observations, given our full understanding of this system, and discuss whether there are really two circumnuclear star forming rings in this galaxy.

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Formation of nuclear rings of barred galaxies and star formation therein

Kim

2013

Proc. IAU

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Barred galaxies contain substructures such as a pair of dust lanes and nuclear rings, with the latter being sites of intense star formation. We study the substructure formation as well as star formation in nuclear rings using numerical simulations. We find that nuclear rings form not by the Lindblad resonances, as previously thought, but by the centrifugal barrier that inflowing gas along dust lanes cannot overcome. This predicts a smaller ring in a more strongly barred galaxy, consistent with observations. Star formation rate (SFR) in a nuclear ring is determined primarily by the mass inflow rate to the ring. In our models, the SFR typically shows a short strong burst associated with the rapid gas infall and stays very small for the rest of the evolution. When the SFR is low, ages of young star clusters exhibit an azimuthal gradient along the ring since star formation takes place mostly near the contact points between the dust lanes and the nuclear ring. When the SFR is large, on the other hand, star formation is widely distributed throughout the whole length of the ring, with no apparent age gradient of star clusters. Since observed ring star formation appears long-lived with episodic bursts, our results suggest that the bar region should be replenished continually with fresh gas from outside.

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How does star formation proceed in the circumnuclear starburst ring of NGC 6951?

Cited by 23 publications

References 43 publications

Equilibrium Sequences and Gravitational Instability of Rotating Isothermal Rings

Equilibrium Sequences and Gravitational Instability of Rotating Isothermal Rings

Explaining two circumnuclear star forming rings in NGC 5248

Formation of nuclear rings of barred galaxies and star formation therein

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