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Molecular Gas Dynamics in NGC 6946: a Bar-driven Nuclear Starburst "Caught in the Act"

E. Schinnerer·T. Boeker·E. Emsellem·U. Lisenfeld
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Abstract

We present high angular resolution ~1" and 0.6" mm-interferometric observations of the 12CO(1-0) and 12CO(2-1) line emission in the central 300pc of the late-type spiral galaxy NGC6946. The data, obtained with the IRAM Plateau de Bure Interferometer (PdBI), allow the first detection of a molecular gas spiral in the inner ~10" (270pc) with a large concentration of molecular gas (M(H_2) ~1.6x10^7M_sun) within the inner 60pc. This nuclear clump shows evidence for a ring-like geometry with a radius of ~10pc as inferred from the p-v diagrams. Both the distribution of the molecular gas as well as its kinematics can be well explained by the influence of an inner stellar bar of about 400pc length. A qualitative model of the expected gas flow shows that streaming motions along the leading sides of this bar are a plausible explanation for the high nuclear gas density. Thus, NGC6946 is a prime example of molecular gas kinematics being driven by a small-scale, secondary stellar bar.

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E. Schinnerer, T. Boeker, E. Emsellem, U. Lisenfeld. 2006-05-30. Molecular Gas Dynamics in NGC 6946: a Bar-driven Nuclear Starburst "Caught in the Act". https://doi.org/10.1086/506265

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