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Session 49 - Starburst Galaxies.
Display session, Tuesday, January 16
North Banquet Hall, Convention Center
We present the high-resolution (6.6\times3.7 aresec) CS J=2\rightarrow1 map of the nearby starburst galaxy NGC 253, made with the 6-element BIMA array. Dense gas traced by the CS transition resides within a radius of \sim20 arcsec (\sim290 pc) of the nucleus. Typical gas density and CS column density is of the order of 10^4 cm^-3 and 10^15 cm^-2 respectively. The dense gas structure revealed by its kinematic appears to include a inner torus, a pair of spin-up arms and an outer gas belt. The inner torus has a radius of \sim6 arcsec (87 pc) and an average rotation velocity of \sim63 km\,s^-1; the spin-up arms have a pitch angle of \sim17^o, eclipsing the rotating torus in one end and connecting to the outer gas belt in the other end. Gas flows along the arms at a speed of \sim65 km\,s^-1 from the outer gas belt to the inner torus. The outer gas belt starts at a radius of \sim14 arcsec (204 pc). It rotates at a velocity of \sim50 km\,s^-1, and at the same time collapse inward at a speed of 65 km\,s^-1. Clearly, the spin-up arms are playing a very important role in channelling in gas to the nucleus from outer regions that fuels the starburst.
This research was performed at the Laboratory for Astronomical Imaging at the University of Illinois, and is completed at the Jet Propulsion Laboratory, California Institute of Technology, where R.P. holds a National Research Council Associateship.
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