2011A&A...532A..53G


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.08CEST04:19:12

2011A&A...532A..53G - Astronomy and Astrophysics, volume 532A, 53-53 (2011/8-1)

Revisiting the shocks in BHR 71: new observational constraints and H2O predictions for Herschel.

GUSDORF A., GIANNINI T., FLOWER D.R., PARISE B., GUESTEN R. and KRISTENSEN L.E.

Abstract (from CDS):

During the formation of a star, material is ejected along powerful jets that impact the ambient material. This outflow phenomenon plays an important role in the regulation of star formation. Understanding the associated shocks and their energetic effects is therefore essential to the study of star formation. We present comparisons of shock models with observations of H2 and SiO emission in the bipolar outflow BHR71. Such comparisons constitute a good way to constrain the type, velocity and age of the shock waves operating in this environment, as well as the physical conditions in the pre-shock region, e.g. density and magnetic field. They also provide a method for studying silicon in shocked regions. We make use of all the preliminary physical constraints obtained through such comparisons to predict water emission, under the basic assumption that the emission regions of the considered species coincide, at the resolution of currently available observations. New SiO observations from APEX are presented, and combined with Spitzer and ground-based observations of H2 to constrain shock models. The shock regions associated with targeted positions in the molecular outflow are studied by means of a code that generates one-dimensional models of the propagation of stationary shock waves, and approximations to non-stationary ones. The emission of H2 is dealt with in the code, whereas the emission of SiO and H2O are calculated by means of an external module, based on the LVG approximation. This external code provides local and integrated intensities for the lines of these species. A grid of models is used, covering shock velocities in the range 10≤vs≤35km/s, and pre-shock gas densities 104≤nH≤106cm–3. The magnetic field strength varies from about 45µG to 600µG. The SiO emission in the inner part of the outflow is concentrated near the apex of the corresponding bow-shock that is also seen in the pure rotational transitions of H2. Simultaneous modelling is possible for H2 and SiO and leads to constraints on the silicon pre-shock distribution on the grain mantles and/or cores. The best-fitting models are found to be of the non-stationary type, but the degeneracy of the solutions is still large. Pre-shock densities of 104 and 105cm–3 are investigated, and the associated best-model candidates have rather low velocity (respectively, 20-30 and 10-15km/s) and are not older than 1000 years. We provide emission predictions for water, focusing on the brightest transitions, to be observed with the PACS and HIFI instruments of the Herschel Telescope.

Abstract Copyright:

Journal keyword(s): stars: formation - ISM: jets and outflows - ISM: individual objects: BHR71 - submillimeter: ISM - infrared: ISM

Nomenclature: Fig. 1, Table 1: [GGF2011] SiO peak N=1, [GGF2011] SiO knot N=1.

Simbad objects: 20

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Number of rows : 20

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 LDN 1448 DNe 03 22.5 +30 35           ~ 466 0
2 NGC 2071 RNe 05 47 10 +00 18.0           ~ 609 1
3 RAFGL 4078 C* 07 45 02.4140089106 -71 19 45.852846228       15.92 12.72 C 44 0
4 HH 320B HH 12 01 31.3 -65 08 05           ~ 4 0
5 HH 320A HH 12 01 32.2 -65 08 13           ~ 6 0
6 [GMC2004] 5 out 12 01 32.60 -65 08 23.3           ~ 3 0
7 HH 320 HH 12 01 32.7 -65 08 11           ~ 15 0
8 [GGF2011] SiO peak out 12 01 33.80 -65 07 24.0           ~ 1 0
9 [B2001b] IRS 2 Y*O 12 01 34.0 -65 08 44           ~ 24 0
10 [GMC2004] 6 out 12 01 36.00 -65 08 23.3           ~ 3 0
11 [GGF2011] SiO knot out 12 01 36.00 -65 07 34.0           ~ 1 0
12 HH 321 HH 12 01 36.3 -65 09 34           ~ 12 0
13 HH 321A HH 12 01 36.4 -65 09 33           ~ 6 0
14 BHR 71 MoC 12 01 36.810 -65 08 49.22           ~ 119 0
15 [GMC2004] 8 out 12 01 38.90 -65 10 07.0           ~ 3 0
16 HH 321B HH 12 01 39.2387867591 -65 10 18.089882721           ~ 5 0
17 HH 54 HH 12 55 49.5 -76 56 08           ~ 118 0
18 WOS 48 C* 15 23 05.0744336371 -51 25 58.881494593   17.85 16.66 14.51 10.18 C 118 1
19 LDN 1157 DNe 20 39 06.4 +68 02 13           ~ 484 0
20 [DE95] LDN 1157 B1 out 20 39 11 +68 01.3           ~ 180 0

    Equat.    Gal    SGal    Ecl

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2020.07.08-04:19:12

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