2007A&A...469..561K


C.D.S. - SIMBAD4 rel 1.7 - 2021.03.01CET09:21:48

2007A&A...469..561K - Astronomy and Astrophysics, volume 469, 561-574 (2007/7-2)

Excitation conditions in the Orion molecular cloud obtained from observations of ortho- and para-lines of H2.

KRISTENSEN L.E., RAVKILDE T.L., FIELD D., LEMAIRE J.L. and PINEAU DES FORETS G.

Abstract (from CDS):

We seek to study excitation mechanisms in the inner region of the Orion Molecular Cloud by comparing observations of ortho- and para-lines of H2 with theoretical models of slow shocks and photodissociation regions. K-band observations of H2 obtained with the Canada-France-Hawaii 3.6m telescope using the PUEO adaptive optics system are reported. Data were centered on the Becklin-Neugebauer object northwest of the Trapezium stars. Narrow-band filters were used to isolate emission from the v=1-0 S(1) ortho- and v=1-0 S(0) para-lines at a spatial resolution of 0.45" (∼200AU). We are able to combine their intensity to obtain the column densities of rovibrationally excited ortho and para H2 levels of the molecular gas at high spatial resolution. The resulting line ratios show variations between 2 and the statistical equilibrium value of 6. We find 4 different classes of emission, characterised by the ratio of the v=1-0 S(1) and S(0) line brightness and the absolute line brightness. Shock models are used to estimate the physical properties of pre-shock density and shock velocity for these 4 classes. We find that the pre-shock density is in the range of 105-107cm–3 and shock velocities lie between 10 and 40km/s. Studies of individual objects, using additional constraints of shock velocity and width, allow quite precise physical conditions to be specified in three prominent bow shocks, one with a shock speed of 18±2km/s and pre-shock density 1±0.5x106cm–3 (3σ) and two with shock speeds of ∼36±2km/s and pre-shock densities of 7.5±2.5x104cm–3.

Abstract Copyright:

Journal keyword(s): ISM: individual objects: OMC1 - ISM: kinematics and dynamics - ISM: molecules - shock waves - ISM: lines and bands

Simbad objects: 13

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Number of rows : 13

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 NGC 253 SyG 00 47 33.134 -25 17 19.68   8.03   6.94 8.1 ~ 2998 2
2 NAME OMC-1 MoC 05 35 14 -05 22.4           ~ 1038 2
3 V* V2254 Ori Or* 05 35 14.11296 -05 22 22.7316           B 297 2
4 [RLK73] IRc 2 IR 05 35 14.51548 -05 22 30.5943           ~ 590 1
5 COUP 657 * 05 35 14.7000 -05 22 49.400           ~ 16 0
6 V* V1330 Ori BY* 05 35 14.9157450029 -05 22 39.209342428   15.040 13.940   11.632 K4 69 0
7 V* V1331 Ori Ro* 05 35 15.3444129558 -05 22 15.587976220   15.777 14.474   11.707 K3e 51 0
8 Parenago 1861 Y*O 05 35 15.4842897287 -05 22 48.580844541     16.180   12.874 M2 40 1
9 COUP 742 * 05 35 15.8380240259 -05 22 45.853745273     16.466   13.432 M3e 35 0
10 * tet01 Ori C ** 05 35 16.4664092288 -05 23 22.897102710 4.20 5.15 5.13 4.91 4.73 O7Vp 1294 1
11 NAME Trapezium Cluster As* 05 35 16.5 -05 23 14           ~ 1497 1
12 NAME Ori Region reg 05 35 17.30 -05 23 28.0           ~ 499 0
13 NAME ORI MOL CLOUD MoC 05 56 -01.8           ~ 888 1

    Equat.    Gal    SGal    Ecl

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