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Astron. Astrophys. 348, 685-692 (1999)


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HI spatial distribution in the galaxy NGC 3783

J.A. García-Barreto 1, F. Combes 2, B. Koribalski 3 and J. Franco 1

1 Instituto de Astronomía, Universidad Nacional Autónoma de México, Apartado Postal 70-264, México D.F. 04510, México
2 DEMIRM, Observatoire de Paris, 61 Av. de l'Observatoire, F-75014 Paris, France
3 Australia Telescope National Facility, CSIRO, P.O. Box 76, Epping, NSW 2121, Australia

Received 14 April 1999 / Accepted 29 June 1999

Abstract

We have mapped the emission from atomic hydrogen at [FORMULA]=21 cm from the galaxy NGC 3783 with the Australia Telescope Compact Array. Our main results are: a) the HI morphology is irregular and perturbed, gathered in three blobs apparently unrelated to the optical morphology; b) the observed HI velocity distribution indicates a normal disk in differential rotation with a constant velocity out to a radius of 160" (30 kpc), c) the inclination of the disk is about 25o with the kinematic major axis at a position angle slightly different from that of the stellar bar, d) the HI mass inside a radius of 18" is only [FORMULA] [FORMULA], the total HI mass within 180" is [FORMULA] [FORMULA] and the dynamical mass is [FORMULA] [FORMULA]. The bulk of the gas in NGC 3783 is outside the diameter of the stellar bar; e) Numerical simulations of the gas flow in the barred potential derived from the red image indicate that the pattern speed is [FORMULA] = 38 km/s/kpc: the ring of H[FORMULA] emitting regions encircling the bar would then correspond to UHR, and the H[FORMULA] accumulation in the center to a nuclear ring. Various possibilities are discussed to account for the active nucleus fuelling.

Key words: galaxies: active – galaxies: general – galaxies: individual: NGC 3783 – galaxies: kinematics and dynamics – galaxies: spiral

Send offprint requests to: J.A. García-Barreto (tony@astroscu.unam.mx)

© European Southern Observatory (ESO) 1999

Online publication: August 13, 199

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