2015A&A...575A...9P


C.D.S. - SIMBAD4 rel 1.7 - 2020.02.23CET08:54:27

2015A&A...575A...9P - Astronomy and Astrophysics, volume 575A, 9-9 (2015/3-1)

Detection of a large fraction of atomic gas not associated with star-forming material in M17 SW.

PEREZ-BEAUPUITS J.P., STUTZKI J., OSSENKOPF V., SPAANS M., GUESTEN R. and WIESEMEYER H.

Abstract (from CDS):

The [CII] 158µm line is one of the dominant coolants of the ISM, and an important probe with which to study the star formation process. Recent Herschel/HIFI and SOFIA/GREAT observations showed that assuming the total velocity-integrated intensity of this line is directly associated with the star-forming material is inadequate. We probe the column densities and masses traced by the ionized and neutral atomic carbon with spectrally resolved maps, and compare them to the diffuse and dense molecular gas traced by [CI] and low-J CO lines toward the star-forming region M17 SW. We mapped a 4.1 pcx4.7 pc region in the [CI] 609µm line using the APEX telescope, as well as the CO isotopologues with the IRAM 30 m telescope. Because of the velocity-resolved spectra, we analyze the data based on velocity channel maps that are 1km/s wide. We correlate their spatial distribution with that of the [CII] map obtained with SOFIA/GREAT. Optically thin approximations were used to estimate the column densities of [CI] and [CII] in each velocity channel. The distribution of the emission from the isotopologues 13CO, CO17, and C18O resembles more closely that of the [CI] emission than that of the 12CO emission. The spatial distribution of the [CI] and all CO isotopologues emission was found to be associated with that of [CII] in about 20%-80% of the mapped region, with the high correlation found in the central (15-23km/s) velocity channels. The excitation temperature of [CI] ranges between 40 K and 100 K in the inner molecular region of M17 SW. Excitation temperatures up to 200 K are found along the ridge. Column densities in 1km/s channels between ∼1015 cm and ∼1017 cm were found for [CI]. Just ∼20 % of the velocity range (∼40km/s) that the [CII] line spans is associated with the star-forming material traced by [CI] and CO. The total (integrated over the 0-40km/s velocity range) gas mass estimated from the [CII] emission gives a lower limit of ∼4.4x103M. A very large fraction of at least 64% of this mass is not associated with the star-forming material in M17 SW. We also found that about 36%, 17%, and 47% of the [CII] emission is associated with the HII, HI, and H2 regimes, respectively. Comparisons with the H41α line shows an ionization region mixed with the neutral and part of the molecular gas, in agreement with the clumped structure and dynamical processes at play in M17 SW. These results are also relevant to extra-galactic studies in which [CII] is often used as a tracer of star-forming material.

Abstract Copyright:

Journal keyword(s): ISM: atoms - ISM: molecules - submillimeter: ISM - ISM: clouds

VizieR on-line data: <Available at CDS (J/A+A/575/A9): list.dat fits/*>

Simbad objects: 18

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Number of rows : 18

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 NGC 253 SyG 00 47 33.134 -25 17 19.68   8.03   6.94 8.1 ~ 2888 2
2 M 33 GiG 01 33 50.904 +30 39 35.79 6.17 6.27 5.72     ~ 5072 1
3 NAME Orion Bright Bar reg 05 35 22.30 -05 24 33.0           ~ 702 0
4 NAME ORI MOL CLOUD MoC 05 56 -01.8           ~ 830 1
5 NGC 3603 HII 11 15 24 -61 15.0           ~ 929 2
6 NAME Sgr B2 (North) Rad 17 47 20.2 -28 22 21           ~ 504 1
7 NAME M 17 SW SFR 18 20 23.1 -16 11 43           ~ 246 0
8 NAME M 17 UC1 HII 18 20 24.82 -16 11 34.9           ~ 46 1
9 BD-16 4816 * 18 20 27.6346 -16 12 01.165   11.34 9.72 8.8   K0: 22 1
10 [BFT2007] 536 * 18 20 29.811 -16 10 45.58           O4V 8 0
11 NAME Kleinmann Star ** 18 20 29.862 -16 10 44.93 17.04 16.28 14.13     O4+O4 56 1
12 [BFT2007] 543 * 18 20 29.90 -16 10 44.4           O4V 8 0
13 NGC 6618 OpC 18 20 47 -16 10.3           ~ 1469 0
14 W 49 SFR 19 10 20 +09 07.7           ~ 504 1
15 W 51 SNR 19 23 50 +14 06.0           ~ 1130 1
16 NGC 7023 BNe 21 01 36.9 +68 09 48   7.20       ~ 611 0
17 SH 2-125 HII 21 53 30 +47 21.2           ~ 38 1
18 SH 2-140 OpC 22 19 07.8 +63 17 07           ~ 630 2

    Equat.    Gal    SGal    Ecl

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2020.02.23-08:54:27

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