Bibcode
Munoz-Tunon, C.; Vilchez, J. M.; Castaneda, H. O.
Bibliographical reference
Astronomy and Astrophysics (ISSN 0004-6361), vol. 278, no. 2, p. 364-370
Advertised on:
11
1993
Citations
10
Refereed citations
10
Description
We present high spectral and spatial resolution spectroscopy of the
nuclear starburst region of the galaxy NGC 253. Two slit positions,
matching the major and minor axes on the galaxy, have been taken. These
cover H-alpha and (N II) lines as well as the (S II) doublet. The
attained resolution, together with good seeing conditions, have allowed
the detection of line profile variations on the scale of arcseconds. The
global kinematical features along the major and minor axes yield a lower
limit to the total extension of the nuclear starburst of about 725 pc.
The shape of the line profiles together with the observed structure of
the velocity curves imply emitting region cells of about 160 pc, a size
typical of OB associations in our galaxy. A detailed analysis of the
incremental flux ratio (NII)/H-alpha leads to the conclusion that there
are differences in the excitation conditions and/or abundances, that
change with the velocity of the gaseous components. The evidence thus
implies that the activity of the nuclear starburst of NGC 253 results
from the joint action of several, coeval, well detached star forming
centers, rather than a single super-massive one.