Gas kinematics in the nucleus of NGC 6946

Munoz-Tunon, C.; Vilchez, J. M.
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Astronomy and Astrophysics (ISSN 0004-6361), vol. 186, no. 1-2, Nov. 1987, p. 25-29.

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A complex kinematical structure is inferred from the analysis of high resolution spectra of the nuclear region of the galaxy NGC 6946. The spatial resolution of the observations allowed the authors to resolve a dynamically inhomogeneous area of approximately 10 arcseconds in diameter, very close to the centre of the galaxy. Within this region the emission lines show non-gaussian profiles which are generally split into at least two main components, differing in velocity by approximately 50 km s-1. These line profiles show an intricate structure in both the Hα and the [N II] lines, indicating that self-absorption effects in Hα can be ruled out. A simple interpretation of the kinematical structure in terms of a rotational velocity curve alone does not appear to be realistic. An interpretation based on stellar winds plus supernova explosions as proposed by Beckman et al. (1986), is preferred rather than a model with purely gravitationally coupled motions. The authors examine this solution in the light of the particularly rich star formation history of NGC 6946.