2010A&A...515A..71C


C.D.S. - SIMBAD4 rel 1.7 - 2021.03.03CET01:31:47

2010A&A...515A..71C - Astronomy and Astrophysics, volume 515, A71-71 (2010/6-1)

Vibrationally excited HC3N in NGC 4418.

COSTAGLIOLA F. and AALTO S.

Abstract (from CDS):

We investigate the molecular gas properties of the deeply obscured luminous infrared galaxy NGC 4418. We address the excitation of the complex molecule HC3N to determine whether its unusually luminous emission is related to the nature of the buried nuclear source. We use IRAM 30 m and JCMT observations of rotational and vibrational lines of HC3N to model the excitation of the molecule by means of rotational diagrams. We report the first confirmed extragalactic detection of vibrational lines of HC3N. We detect 6 different rotational transitions ranging from J=10-9 to J=30-29 in the ground vibrational state and obtain a tentative detection of the J=38-37 line. We also detect 7 rotational transitions of the vibrationally excited states v6 and v7, with angular momenta ranging from J=10-9 to 28-27. The energies of the upper states of the observed transitions range from 20 to 850K. In the optically thin regime, we find that the rotational transitions of the vibrational ground state can be fitted for two temperatures, 30K and 260K, while the vibrationally excited levels can be fitted for a rotational temperature of 90K and a vibrational temperature of 500 K. In the inner 300pc of NGC 4418, we estimate a high HC3N abundance, of the order of 10–7. The excitation of the HC3N molecule responds strongly to the intense radiation field and the presence of warm, dense gas and dust at the center of NGC 4418. The intense HC3N line emission is a result of both high abundances and excitation. The properties of the HC3N emitting gas are similar to those found for hot cores in Sgr B2, which implies that the nucleus (<300pc) of NGC 4418 is reminiscent of a hot core. The potential presence of a compact, hot component (T=500K) is also discussed.

Abstract Copyright:

Journal keyword(s): galaxies: evolution - globular clusters: individual: NGC 4418 - galaxies: starburst - galaxies: active - radio lines: ISM - ISM: molecules

Simbad objects: 9

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Number of rows : 9

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 NGC 253 SyG 00 47 33.134 -25 17 19.68   8.03   6.94 8.1 ~ 3000 2
2 IC 342 SBG 03 46 48.514 +68 05 45.98   10.5       ~ 1406 1
3 NAME Orion Core ? 05 35 14.5 -05 22 30           ~ 177 0
4 NAME Ori A MoC 05 38 -07.1           ~ 2739 0
5 M 82 IG 09 55 52.430 +69 40 46.93 9.61 9.30 8.41     ~ 5426 6
6 NGC 4355 Sy2 12 26 54.628 -00 52 39.51   14.21 13.37     ~ 420 2
7 NGC 4945 Sy2 13 05 27.279 -49 28 04.44   9.31 14.40 7.55   ~ 1301 2
8 GAL 000.0+00.0 gam 17 45 39.60213 -29 00 22.0000           ~ 12003 0
9 NAME Sgr B2 MoC 17 47 20.4 -28 23 07           ~ 1980 1

    Equat.    Gal    SGal    Ecl

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2021.03.03-01:31:47

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