2014A&A...570A..49L


C.D.S. - SIMBAD4 rel 1.7 - 2019.10.21CEST03:11:29

2014A&A...570A..49L - Astronomy and Astrophysics, volume 570A, 49-49 (2014/10-1)

SiO excitation from dense shocks in the earliest stages of massive star formation.

LEURINI S., CODELLA C., LOPEZ-SEPULCRE A., GUSDORF A., CSENGERI T. and ANDERL S.

Abstract (from CDS):

Molecular outflows are a direct consequence of accretion, and therefore they represent one of the best tracers of accretion processes in the still poorly understood early phases of high-mass star formation. Previous studies suggested that the SiO abundance decreases with the evolution of a massive young stellar object probably because of a decay of jet activity, as witnessed in low-mass star-forming regions. We investigate the SiO excitation conditions and its abundance in outflows from a sample of massive young stellar objects through observations of the SiO(8-7) and CO(4-3) lines with the APEX telescope. Through a non-local thermodynamic equilibrium analysis, we find that the excitation conditions of SiO increase with the velocity of the emitting gas. We also compute the SiO abundance through the SiO and CO integrated intensities at high velocities. For the sources in our sample we find no significant variation of the SiO abundance with evolution for a bolometric luminosity-to-mass ratio of between 4 and 50L/M. We also find a weak increase of the SiO(8-7) luminosity with the bolometric luminosity-to-mass ratio. We speculate that this might be explained with an increase of density in the gas traced by SiO. We find that the densities constrained by the SiO observations require the use of shock models that include grain-grain processing. For the first time, such models are compared and found to be compatible with SiO observations. A pre-shock density of 105cm–3 is globally inferred from these comparisons. Shocks with a velocity higher than 25km/s are invoked for the objects in our sample where the SiO is observed with a corresponding velocity dispersion. Our comparison of shock models with observations suggests that sputtering of silicon-bearing material (corresponding to less than 10% of the total silicon abundance) from the grain mantles is occurring.

Abstract Copyright:

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

VizieR on-line data: <Available at CDS (J/A+A/570/A49): list.dat fits/*>

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 - 2019
#notes
1 HH 212 HH 05 43 51.41 -01 02 53.1           ~ 257 1
2 [BSM2002] 18151-1208 2 cor 18 17 50.36 -12 07 54.8           ~ 17 0
3 AGAL G019.286+00.082 Y*? 18 25 52.1 -12 04 50           ~ 21 0
4 [RJS2006] MSXDC G019.27+00.07 MM1 MoC 18 25 58.29 -12 04 13.5           ~ 15 0
5 [FC2000] G019.61-0.24 A HII 18 27 38.16 -11 56 40.2           ~ 4 0
6 OH 20.1 -0.1 SFR 18 28 10.3918 -11 28 44.164           ~ 104 0
7 RAFGL 5491 mul 18 28 10.7 -11 29 01           ~ 44 0
8 IRAS 18264-1152 cor 18 29 14.6846 -11 50 23.966           ~ 70 1
9 [RJS2006] MSXDC G023.60+00.00 MM1 mm 18 34 11.6 -08 19 06           ~ 13 0
10 RAFGL 7009S Y*O 18 34 20.911 -05 59 42.23           ~ 184 0
11 [RJS2006] MSXDC G023.60+00.00 MM2 mm 18 34 21.1 -08 18 07           ~ 13 0
12 IRAS 18324-0737 mm 18 35 08.1 -07 35 04           ~ 16 0
13 [RJS2006] MSXDC G025.04-00.20 MM1 mm 18 38 10.2 -07 02 34           ~ 10 0
14 SNR G030.8-00.0 SNR 18 47 32 -01 56.5           ~ 423 0
15 GAL 034.4+00.23 HII 18 53 17.4 +01 24 55           ~ 72 1
16 [ZYL2017] G34-1 cor 18 53 18.0 +01 25 24           ~ 44 0
17 [RJS2006] MSXDC G034.43+00.24 MM3 mm 18 53 20.4 +01 28 23           ~ 30 0
18 [BNM96] 043.793-0.125 Y*O 19 11 54.016 +09 35 49.46           ~ 58 2
19 LDN 1157 DNe 20 39 06.4 +68 02 13           ~ 463 0
20 [DE95] LDN 1157 B1 out 20 39 11 +68 01.3           ~ 163 0
21 LDN 1148 DNe 20 40 31.6 +67 21 45           ~ 59 0

    Equat.    Gal    SGal    Ecl

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2019.10.21-03:11:29

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