2017A&A...599A..98P


C.D.S. - SIMBAD4 rel 1.7 - 2021.03.05CET17:34:23

2017A&A...599A..98P - Astronomy and Astrophysics, volume 599A, 98-98 (2017/3-1)

The anatomy of the Orion B giant molecular cloud: A local template for studies of nearby galaxies.

PETY J., GUZMAN V.V., ORKISZ J.H., LISZT H.S., GERIN M., BRON E., BARDEAU S., GOICOECHEA J.R., GRATIER P., LE PETIT F., LEVRIER F., OBERG K.I., ROUEFF E. and SIEVERS A.

Abstract (from CDS):

Context. Molecular lines and line ratios are commonly used to infer properties of extra-galactic star forming regions. The new generation of millimeter receivers almost turns every observation into a line survey. Full exploitation of this technical advancement in extra-galactic study requires detailed bench-marking of available line diagnostics.
Aims. We aim to develop the Orion B giant molecular cloud (GMC) as a local template for interpreting extra-galactic molecular line observations.
Methods. We use the wide-band receiver at the IRAM-30 m to spatially and spectrally resolve the Orion B GMC. The observations cover almost 1 square degree at 26'' resolution with a bandwidth of 32GHz from 84 to 116GHz in only two tunings. Among the mapped spectral lines are the 12CO, 13CO, C18O, C17O, HCN, HNC, 12CN, C2H, HCO+, N2H+ (1-0), and 12CS, 32SO, SiO, c-C3H2, CH3OH (2-1) transitions.
Results. We introduce the molecular anatomy of the Orion B GMC, including relationships between line intensities and gas column density or far-UV radiation fields, and correlations between selected line and line ratios. We also obtain a dust-traced gas mass that is less than approximately one third the CO-traced mass, using the standard XCO conversion factor. The presence of over-luminous CO can be traced back to the dependence of the CO intensity on UV illumination. As a matter of fact, while most lines show some dependence on the UV radiation field, CN and C2H are the most sensitive. Moreover, dense cloud cores are almost exclusively traced by N2H+. Other traditional high-density tracers, such as HCN (1-0), are also easily detected in extended translucent regions at a typical density of ∼500H2cm–3. In general, we find no straightforward relationship between line critical density and the fraction of the line luminosity coming from dense gas regions.
Conclusions. Our initial findings demonstrate that the relationships between line (ratio) intensities and environment in GMCs are more complicated than often assumed. Sensitivity (i.e., the molecular column density), excitation, and, above all, chemistry contribute to the observed line intensity distributions, and they must be considered together when developing the next generation of extra-galactic molecular line diagnostics of mass, density, temperature, and radiation field.

Abstract Copyright: © ESO, 2017

Journal keyword(s): galaxies: ISM - ISM: clouds - HII regions - radio lines: galaxies - astrochemistry - astrochemistry

Simbad objects: 28

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Number of rows : 28

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 ~ 3002 2
2 [MTH2008] B MoC 02 41 55.0 +59 36 28           ~ 4 0
3 UGCA 39 GiG 02 41 55.092 +59 36 14.73   16       ~ 328 1
4 M 77 GiP 02 42 40.771 -00 00 47.84 9.70 9.61 8.87 10.1 9.9 ~ 4180 2
5 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 5868 1
6 NAME Taurus Complex SFR 04 41.0 +25 52           ~ 3650 0
7 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 15214 1
8 * sig Ori Y*O 05 38 44.7665260139 -02 36 00.284709290 2.54 3.58 3.79 3.87 4.11 O9.5V 754 0
9 * zet Ori ** 05 40 45.52666 -01 56 33.2649 0.50 1.56 1.77 1.85 2.05 O9.7Ib+B0III 334 0
10 NAME Horsehead Nebula DNe 05 40 59.0 -02 27 30           ~ 457 0
11 IC 434 HII 05 41 -02.5           ~ 79 1
12 NAME NGC 2023 MM 1 Y*O 05 41 24.9 -02 18 09           ~ 21 0
13 NGC 2023 RNe 05 41 37.9 -02 15 52           ~ 580 1
14 HD 37903 Em* 05 41 38.3889407943 -02 15 32.476182358 7.32 7.94 7.83 7.64 7.52 B3IV 330 1
15 NAME Ori B MoC 05 41 43.0 -01 54 44           ~ 1213 0
16 NGC 2024 Cl* 05 41 43 -01 50.5           ~ 1084 1
17 [MCK88] NGC 2024 FIR 5 cor 05 41 44.6 -01 55 38           ~ 91 0
18 [BCB89] IRS 2b Y*O 05 41 45.490 -01 54 28.78           O8V 38 1
19 [BCB89] IRS 2 Y*O 05 41 45.81 -01 54 29.8           B 95 0
20 IC 435 RNe 05 43 00.5 -02 18 45           ~ 44 0
21 HD 38087 ** 05 43 00.5750795483 -02 18 45.388281574 7.96 8.40 8.29 8.06 7.89 B3II 152 1
22 LDN 1630 DNe 05 45.5 -00 59           ~ 356 0
23 M 82 IG 09 55 52.430 +69 40 46.93 9.61 9.30 8.41     ~ 5430 6
24 Mrk 231 Sy1 12 56 14.2340989340 +56 52 25.238555193   14.68 13.84     ~ 1818 3
25 M 51 GiP 13 29 52.698 +47 11 42.93   9.26 8.36 8.40   ~ 3893 4
26 M 83 SBG 13 37 00.919 -29 51 56.74 8.85 8.11 7.52 7.21   ~ 2280 2
27 IC 4553 SyG 15 34 57.22396 +23 30 11.6084   14.76 13.88     ~ 2727 4
28 NGC 7469 Sy1 23 03 15.674 +08 52 25.28 12.60 13.00 12.34     ~ 1919 3

    Equat.    Gal    SGal    Ecl

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2021.03.05-17:34:23

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