2012A&A...546A..75M


C.D.S. - SIMBAD4 rel 1.7 - 2021.01.27CET12:04:35

2012A&A...546A..75M - Astronomy and Astrophysics, volume 546A, 75-75 (2012/10-1)

Chemistry of C3 and carbon chain molecules in DR21(OH).

MOOKERJEA B., HASSEL G.E., GERIN M., GIESEN T., STUTZKI J., HERBST E., BLACK J.H., GOLDSMITH P.F., MENTEN K.M., KRELOWSKI J., DE LUCA M., CSENGERI T., JOBLIN C., KAZMIERCZAK M., SCHMIDT M., GOICOECHEA J.R. and CERNICHARO J.

Abstract (from CDS):

C3 is the smallest pure carbon chain detected in the dense environment of star-forming regions, although diatomic C2 is detected in diffuse clouds. Measurement of the abundance of C3 and the chemistry of its formation in dense star-forming regions has remained relatively unexplored. We aim to identify the primary C3 formation routes in dense star-forming regions following a chemical network producing species like CCH and c-C3H2 in the star-forming cores associated with DR21(OH), a high-mass star-forming region. We observed velocity resolved spectra of four ro-vibrational far-infrared transitions of C3 between the vibrational ground state and the low-energy ν2 bending mode at frequencies between 1654-1897GHz using HIFI on board Herschel, in DR21(OH). Several transitions of CCH and c-C3H2 were also observed with HIFI and the IRAM 30m telescope. Rotational temperatures and column densities for all chemical species were estimated. A gas and grain warm-up model was used to obtain estimates of densities and temperatures of the envelope. The chemical network in the model was used to identify the primary C3 forming reactions in DR21(OH). We detected C3 in absorption in four far-infrared transitions, P(4), P(10), Q(2), and Q(4). The continuum sources MM1 and MM2 in DR21(OH), though spatially unresolved, are sufficiently separated in velocity to be identified in the C3 spectra. All C3 transitions are detected from the embedded source MM2 and the surrounding envelope, whereas only Q(4) and P(4) are detected toward the hot core MM1. The abundance of C3 in the envelope and MM2 is ∼6x10–10 and ∼3x10–9, respectively. For CCH and c-C3H2, we only detect emission from the envelope and MM1. The observed CCH, C3 and c-C3H2 abundances are most consistent with a chemical model with nH2∼5x106cm–3, a post-warm-up dust temperature Tmax=30K, and a time of ∼ 0.7-3Myr. Post-warm-up gas phase chemistry of CH4 released from the grain at t∼0.2Myr and lasting for 1Myr can explain the observed C3 abundance in the envelope of DR21(OH), and no mechanism involving photodestruction of PAH molecules is required. The chemistry in the envelope is similar to the warm carbon chain chemistry found in lukewarm corinos. We interpret the observed lower C3 abundance in MM1 as compared to MM2 and the envelope to be due to the destruction of C3 in the more evolved MM1. The timescale for the chemistry derived for the envelope is consistent with the dynamical timescale of 2Myr derived for DR21(OH) in other studies.

Abstract Copyright:

Journal keyword(s): ISM: molecules - ISM: lines and bands - ISM: individual objects: DR21(OH) - astrochemistry - radiative transfer - molecular data

Simbad objects: 16

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Number of rows : 16

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 LDN 1527 DNe 04 39 53 +25 45.0           ~ 515 0
2 IRC +10216 C* 09 47 57.40632 +13 16 43.5648     10.96     C9,5e 2174 0
3 Barnard 228 cor 15 43 00.9 -34 08 48           ~ 64 0
4 IRAS 16293-2422 cor 16 32 22.56 -24 28 31.8           ~ 1071 1
5 NAME Sgr B2 MoC 17 47 20.4 -28 23 07           ~ 1966 1
6 W 31c HII 18 10 29.1 -19 56 05           ~ 306 0
7 W 49n HII 19 10 13.2 +09 06 12           ~ 422 3
8 NAME Cyg X Cld 20 28 41 +41 10.2           ~ 640 1
9 [WSS89] DR 21(OH) MM 2B Rad 20 39 00.2 +42 22 41           ~ 4 0
10 [WSS89] DR 21(OH) MM 2A Rad 20 39 00.4 +42 22 44           ~ 4 0
11 NAME DR 21(OH) MM 2 Mas 20 39 00.4 +42 22 44           ~ 39 0
12 [ZLS2012] SMA6 mm 20 39 01.002 +42 22 48.93           ~ 5 0
13 [MBS2007c] CygX-N44 Rad 20 39 01.01 +42 22 50.2           ~ 363 0
14 [ZLS2012] SMA7 mm 20 39 01.079 +42 22 49.06           ~ 6 0
15 NAME DR 21(OH) MM 1 Mas 20 39 01.1 +42 22 49           ~ 41 0
16 GRS G081.70 +00.50 SFR 20 39 01.6 +42 19 38           O4.5 956 0

    Equat.    Gal    SGal    Ecl

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2021.01.27-12:04:36

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