Astronomy and Astrophysics – Astrophysics
Scientific paper
Feb 1995
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1995a%26a...294...23m&link_type=abstract
Astronomy and Astrophysics 294, 23-32 (1995)
Astronomy and Astrophysics
Astrophysics
19
Ism: Molecules, Galaxies: Ism, Galaxies, Individual: Ngc253, M82, Ic342 Radio Lines: Galaxies
Scientific paper
The detection of extragalactic OCS, the heaviest molecule identified outside the Galaxy, is reported in three rotational transitions toward the bulge of NGC253. Toward M82, OCS has been tentatively detected. Abundances are consistent with models for warm, dense clouds which have not yet reached chemical equilibrium or with the frequent erosion of grain mantles by C-shocks. This can also explain the large abundances of complex molecules in NGC253. Densities and temperatures of the OCS emitting gas are compared with results from other molecular tracers. From model computations, OCS in the center of NGC253 is emitted by a moderately dense molecular component with n(H_2_)~10^3.4^cm^-3^. This component makes up the bulk of the molecular gas mass. Other molecules also reveal the presence of a much denser component with 10^5-5.5^cm^-3^. A molecular gas mass of ~210^8^Msun_ is estimated for a 180pc sized molecular cloud toward the center of NGC253; the mean H_2_ density is ~2000cm^-3^; and the mean H_2_ column density, 7x10^23^cm^-2^, corresponds to a visual extinction of 700mag. The relative OCS abundance is X(OCS)~10^-8.9^. From detections of the J=2-1 and 3-2 transitions of C^34^S, the density of the dense molecular gas toward the nuclear region of IC342 is n(H_2_)~10^4.6^cm^-3^. Also presented are a possible detection of the HC_3_N J=16-15 line toward IC342 and upper limits for the emission of the DCN J=2-1 line toward NGC253 and IC342. For NGC253, [DCN]/[HCN]<=4x10^-3^.
Chin Y.-N.
Henkel Carsten
Mauersberger Rainer
No associations
LandOfFree
Dense gas in nearby galaxies. VIII. The detection of OCS. does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Dense gas in nearby galaxies. VIII. The detection of OCS., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Dense gas in nearby galaxies. VIII. The detection of OCS. will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1629084