Query : 2016A&A...591A..33R

2016A&A...591A..33R - Astronomy and Astrophysics, volume 591A, 33-33 (2016/7-1)

[C II] 158 µm and [N II] 205 µm emission from IC 342. Disentangling the emission from ionized and photo-dissociated regions.


Abstract (from CDS):

Context. Atomic fine-structure line emission is a major cooling process in the interstellar medium (ISM). In particular the [CII] 158µm line is one of the dominant cooling lines in photon-dominated regions (PDRs). However, it is not confined to PDRs but can also originate from the ionized gas closely surrounding young massive stars. The proportion of the [CII] emission from HII regions relative to that from PDRs can vary significantly.
Aims. We investigate the question of how much of the [CII] emission in the nucleus of the nearby spiral galaxy IC 342 is contributed by PDRs and by the ionized gas. We examine the spatial variations of starburst/PDR activity and study the correlation of the [CII] line with the [NII] 205µm emission line coming exclusively from the HII regions.
Methods. We present small maps of [CII] 158µm and [NII] 205µm lines recently observed with the GREAT receiver on board SOFIA. We present different methods to utilize the superior spatial and spectral resolution of our new data to infer information on how the gas kinematics in the nuclear region influence the observed line profiles. In particular we present a super-resolution method to derive how unresolved, kinematically correlated structures in the beam contribute to the observed line shapes.
Results. We find that the emission coming from the ionized gas shows a kinematic component in addition to the general Doppler signature of the molecular gas. We interpret this as the signature of two bi-polar lobes of ionized gas expanding out of the galactic plane. We then show how this requires an adaptation of our understanding of the geometrical structure of the nucleus of IC 342. Examining the starburst activity we find ratios I([CII])/I(12CO(1-0)) between 400 and 1800 in energy units. Applying predictions from numerical models of HII and PDR regions to derive the contribution from the ionized phase to the total [CII] emission we find that 35-90% of the observed [CII] intensity stems from the ionized gas if both phases contribute. Averaged over the central few hundred parsec we find for the [CII] contribution a HII-to-PDR ratio of 70:30.
Conclusions. The ionized gas in the center of IC 342 contributes more strongly to the overall [CII] emission than is commonly observed on larger scales and than is predicted. Kinematic analysis shows that the majority of the [CII] emission is related to the strong but embedded star formation in the nuclear molecular ring and only marginally emitted from the expanding bi-polar lobes of ionized gas.

Abstract Copyright: © ESO, 2016

Journal keyword(s): galaxies: ISM - galaxies: individual: IC 342 - radio lines: galaxies - radio lines: ISM - galaxies: starburst

VizieR on-line data: <Available at CDS (J/A+A/591/A33): list.dat sp/*>

Simbad objects: 9

goto Full paper

goto View the references in ADS

Number of rows : 9
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 [DRG92] E Cld 03 46 47.53 +68 05 43.5           ~ 10 0
2 [DRG92] B Cld 03 46 47.85 +68 05 46.5           ~ 13 0
3 IC 342 SBG 03 46 48.514 +68 05 45.98   10.5       ~ 1491 1
4 [DRG92] A Cld 03 46 48.55 +68 05 43.6           ~ 13 0
5 [DRG92] C Cld 03 46 49.16 +68 05 50.8           ~ 11 0
6 RMC 136 Cl* 05 38 42.396 -69 06 03.36           ~ 1955 1
7 NAME Fermi Bubbles bub 17 45 -29.0           ~ 411 0
8 NAME Galactic Center reg 17 45 39.60213 -29 00 22.0000           ~ 13892 0
9 NAME Galactic Bulge reg ~ ~           ~ 4163 0

To bookmark this query, right click on this link: simbad:objects in 2016A&A...591A..33R and select 'bookmark this link' or equivalent in the popup menu


© Université de Strasbourg/CNRS

    • Contact