2001A&A...376.1064V


C.D.S. - SIMBAD4 rel 1.7 - 2021.02.26CET17:50:14

2001A&A...376.1064V - Astronomy and Astrophysics, volume 376, 1064-1072 (2001/9-4)

The physical conditions in the PDR of W49N.

VASTEL C., SPAANS M., CECCARELLI C., TIELENS A.G.G.M. and CAUX E.

Abstract (from CDS):

We present ISO-LWS and ground-based SEST observations which probe the Photo Dissociation Region (PDR) of W49N. The ISO-LWS observations consist of low resolution (∼200) grating spectra between 43µm and 197µm, and high resolution (∼104) Fabry-Perot spectra of the [CII] 158µm and [OI] 63 and 145µm lines. The SEST observations consist of C16O J=1->0 and C18O J=2->1 maps of the region. Using all these observations and with the help of a detailed PDR model, we have determined the physical and chemical structure of the PDR of W49N. We find that only a tiny fraction, 2.5%, of the cloud gas is in the atomic form. This gas has an average density n=104cm–3 and a temperature T∼130 K. The PDR is created by a FUV field G0=3x105 times brighter than the average FUV interstellar field, which is emitted by the stars associated with the several HII regions inside the cloud. The photoelectric heating efficiency is very low, ∼10–4, relative to other known PDRs, probably because of the relatively high G0/n ratio. Overall, W49N seems to be one of the youngest giant molecular clouds actively forming stars in the Galaxy, since most of the cloud material is still molecular and dense and not yet dispersed by the several embedded newly formed massive protostars.

Abstract Copyright:

Journal keyword(s): ISM: abundances - ISM: molecules - ISM: atoms - HII regions - ISM: individual: W49N

Simbad objects: 11

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Number of rows : 11

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 NAME OMC-1 MoC 05 35 14 -05 22.4           ~ 1038 2
2 M 42 HII 05 35 17.3 -05 23 28           ~ 3776 0
3 NAME Orion Bright Bar reg 05 35 22.30 -05 24 33.0           ~ 742 0
4 NAME Ori A MoC 05 38 -07.1           ~ 2734 0
5 RMC 136 Cl* 05 38 42.396 -69 06 03.36           ~ 1775 1
6 NGC 2023 RNe 05 41 37.9 -02 15 52           ~ 580 1
7 M 78 RNe 05 46 45.8 +00 04 45   8.0       ~ 349 0
8 M 82 IG 09 55 52.430 +69 40 46.93 9.61 9.30 8.41     ~ 5422 6
9 W 49n HII 19 10 13.2 +09 06 12           ~ 423 3
10 NGC 7023 RNe 21 01 36.9 +68 09 48           ~ 642 0
11 NGC 7027 PN 21 07 01.8 +42 14 10   9.1 10.9     ~ 2352 1

    Equat.    Gal    SGal    Ecl

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2021.02.26-17:50:14

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