2010A&A...522A..91T


C.D.S. - SIMBAD4 rel 1.7 - 2021.03.02CET03:32:44

2010A&A...522A..91T - Astronomy and Astrophysics, volume 522, A91-91 (2010/11-1)

A molecular survey of outflow gas: velocity-dependent shock chemistry and the peculiar composition of the EHV gas.

TAFALLA M., SANTIAGO-GARCIA J., HACAR A. and BACHILLER R.

Abstract (from CDS):

Bipolar outflows from Class 0 protostars often present two components in their CO spectra that have different kinematic behaviors: a smooth outflow wing and a discrete, extremely high-velocity (EHV) peak. To better understand the origin of these two outflow components, we have studied and compared their molecular composition. We carried out a molecular survey of the outflows powered by L1448-mm and IRAS 04166+2706, two sources with prominent wing and EHV components. For each source, we observed a number of molecular lines towards the brightest outflow position and used them to determine column densities for 12 different molecular species. The molecular composition of the two outflows is very similar. It presents systematic changes with velocity that we analyze by dividing the outflow in three chemical regimes, two of them associated with the wing component and the other the EHV gas. The analysis of the two wing regimes shows that species like H2CO and CH3OH favor the low-velocity gas, while SiO and HCN are more abundant in the fastest gas. This fastest wing gas presents strong similarities with the composition of the ``chemically active'' L1157 outflow (whose abundances we re-evaluate in an appendix). We find that the EHV regime is relatively rich in O-bearing species compared to the wing regime. The EHV gas is not only detected in CO and SiO (already reported elsewhere), but also in SO, CH3OH, and H2CO (newly reported here), with a tentative detection in HCO+. At the same time, the EHV regime is relatively poor in C-bearing molecules like CS and HCN, for which we only obtain weak detections or upper limits despite deep integrations. We suggest that this difference in composition arises from a lower C/O ratio in the EHV gas. The different chemical compositions of the wing and EHV regimes suggest that these two outflow components have different physical origins. The wing component is better explained by shocked ambient gas, although none of the existing shock models explains all observed features. We hypothesize that the peculiar composition of the EHV gas reflects its origin as a dense wind from the protostar or its surrounding disk.

Abstract Copyright:

Journal keyword(s): ISM: jets and outflows - ISM: abundances - stars: formation - ISM: molecules

Simbad objects: 21

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Number of rows : 21

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 1448 DNe 03 22.5 +30 35           ~ 475 0
2 [SDA2014] West4 Y*O 03 25 38.83 +30 44 06.2           ~ 244 1
3 IRAS F03226+3033 Y*O 03 25 38.83 +30 44 06.2           ~ 313 0
4 [JCC87] IRAS 4A Y*O 03 29 10.49 +31 13 30.8           ~ 623 1
5 [JCC87] IRAS 4 FIR 03 29 10.9 +31 13 26           ~ 469 0
6 [JCC87] IRAS 4B Y*O 03 29 12.058 +31 13 02.05           ~ 568 0
7 NAME Perseus Cloud SFR 03 35.0 +31 13           ~ 1118 0
8 HH 211 cor 03 43 56.52 +32 00 52.8           ~ 302 0
9 NAME [BM89] L1498 PoC 04 10 51.4 +25 09 58           ~ 187 0
10 LDN 1498 DNe 04 11.0 +24 58           ~ 254 0
11 IRAS 04166+2706 Y*O 04 19 42.62736 +27 13 38.4312           ~ 117 0
12 NAME Tau-Aur Complex SFR 04 30 +25.0           ~ 1246 0
13 LDN 1551 DNe 04 31 30.0 +18 12 30           ~ 779 1
14 NAME Taurus Complex SFR 04 41.0 +25 52           ~ 3642 0
15 NAME [BM89] L1517B cor 04 55 18.8 +30 38 04           ~ 132 0
16 NAME Ori-S6 PoC 05 35 12.7 -05 24 08           ~ 38 0
17 [RLK73] IRc 2 IR 05 35 14.51548 -05 22 30.5943           ~ 590 1
18 BHR 71 MoC 12 01 36.810 -65 08 49.22           ~ 121 0
19 LDN 1157 DNe 20 39 06.4 +68 02 13           ~ 500 0
20 [DE95] LDN 1157 B2 out 20 39 09.3 +68 00 44           ~ 61 0
21 [DE95] LDN 1157 B1 out 20 39 11 +68 01.3           ~ 191 0

    Equat.    Gal    SGal    Ecl

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