2009A&A...507L..25C


Query : 2009A&A...507L..25C

2009A&A...507L..25C - Astronomy and Astrophysics, volume 507, L25-28 (2009/11-4)

Methyl cyanide as tracer of bow shocks in L1157-B1.

CODELLA C., BENEDETTINI M., BELTRAN M.T., GUETH F., VITI S., BACHILLER R., TAFALLA M., CABRIT S., FUENTE A. and LEFLOCH B.

Abstract (from CDS):

L1157-mm is a low-mass protostar driving an outflow which is considered the proto-type of the so-called chemically active outflows. In particular, the blue-shifted lobe B1 stands out for its rich mm-wave spectrum. Our aim is to infer the physical conditions of the molecular gas within L1157-B1. We carried out CH3CN(8K-7K) observations at 2mm with the IRAM Plateau de Bure Interferometer to map L1157-B1. The CH3CN image shows a clumpy structure superimposed to the classical B1 arch-like shape, displaying a unique continuous structure tracing the propagation of a large bow shock. The CH3CN spatial distribution well agrees with that of CH3OH, one of the most abundant species evaporated from dust grain mantles. Thanks to the present CH3CN observations at unprecedented spatial resolution, we determine for the first time the temperature distribution of the B1 bow shock. We obtain values between 57 and 132K, with the highest temperature at the shock apex, thus confirming the association of CH3CN with gas affected by the passage of a shock wave. The NCH3CN column densities are ≃8-40x1012cm–2, depending on the position, leading to CH3CN/CH3OH abundance ratios ≃0.2-1.3x10–3, i.e. values on average smaller than those found in hot-corinos. This suggests that a significant amount of CH3CN is formed in the gas phase: in the shocked L1157-B1 regions the CH3CN abundance may not have reached its maximum yet.

Abstract Copyright:

Journal keyword(s): ISM: individual objects: L1157 - ISM: molecules - stars: formation

Nomenclature: Fig. 1, Table 1: [TB95] BNa (Nos B0f, B1e-B1f) added.

Simbad objects: 7

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Number of rows : 7
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 3C 84 Sy2 03 19 48.1599902040 +41 30 42.108850836   13.10 12.48 11.09   ~ 3835 3
2 ICRF J184916.0+670541 Sy1 18 49 16.07228484 +67 05 41.6802599     20 17.45   ~ 240 1
3 ICRF J202206.6+613658 Sy2 20 22 06.68174620 +61 36 58.8047323     19.5 17.58   ~ 312 1
4 NAME LDN 1157-mm Y*O 20 39 06.2 +68 02 15           ~ 179 0
5 LDN 1157 DNe 20 39 06.4 +68 02 13           ~ 549 0
6 [DE95] LDN 1157 B1 out 20 39 11 +68 01.3           ~ 229 0
7 3C 454.3 Bla 22 53 57.7480438728 +16 08 53.561508864   16.57 16.10 15.22   ~ 2719 2

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2022.12.06-20:01:43

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