A Near Infrared Study of NGC 6946

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Session 75 -- Interacting Galaxies and Starbursts
Display presentation, Wednesday, 11, 1995, 9:20am - 6:30pm

[75.13] A Near Infrared Study of NGC 6946

C.W. Engelbracht, M.J. Rieke, G.H. Rieke (Steward Observatory, University of Arizona, Tucson, AZ 85721), William B. Latter (National Radio Astronomy Observatory, 949 N. Cherry Ave., Tucson, AZ 85721)

New near infrared images and spectroscopy have been obtained for the starburst galaxy NGC 6946. The spectral data were obtained with a long slit cryogenic spectrometer that provides a spectral resolution of about 3,000 and a spatial resolution of 1.2\arcsec\ along the slit. Both broad band images at J, H and K and narrow band images in H$_2$ and Br$\gamma$ were obtained; the narrow band images, along with the spatial information provided by the spectrometer allow us to obtain a picture of the starburst as a function of position in the galaxy. The high signal-to-noise of the spectra gives us access to a large number of weak atomic and molecular features that provide additional information about the starburst. For example, a weak Mg II doublet at 2.14\micron\ indicates a large optical depth in Ly$\beta$ and the presence of high-velocity flows in the nucleus. Detection of multiple [Fe II] emission lines allow us to estimate the electron density in the emitting region. We can use the many recombination lines of Hydrogen in this region to estimate the extinction to the gas. These data and data from the literature are used to derive constraints on the physical conditions within the burst. The derived properties of the burst are compared to output from a starburst modelling code. The code allows estimates of parameters such as the Initial Mass Function and age of the burst. The burst in NGC 6946 is compared to the more nearby and well-studied starburst M 82.

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