C.D.S. - SIMBAD4 rel 1.7 - 2019.09.21CEST09:40:37

2018A&A...617A..45S - Astronomy and Astrophysics, volume 617A, 45-45 (2018/9-1)

Anatomy of the massive star-forming region S106. The [O I] 63 µm line observed with GREAT/SOFIA as a versatile diagnostic tool for the evolution of massive stars.


Abstract (from CDS):

The central area (40''x40'') of the bipolar nebula S106 was mapped in the [OI] line at 63.2µm (4.74THz) with high angular (6'') and spectral (0.24MHz) resolution, using the GREAT heterodyne receiver on board SOFIA. The spatial and spectral emission distribution of [OI] is compared to emission in the CO 16-15, [CII] 158µm, and CO 11-10 lines, mm-molecular lines, and continuum. The [OI] emission is composed of several velocity components in the range from -30 to 25km/s. The high-velocity blue- and red-shifted emission (v=-30 to -9km/s and 8 to 25km/s) can be explained as arising from accelerated photodissociated gas associated with a dark lane close to the massive binary system S106IR, and from shocks caused by the stellar wind and/or a disk-envelope interaction. At velocities from -9 to -4km/s and from 0.5 to 8km/s line wings are observed in most of the lines that we attribute to cooling in photodissociation regions (PDRs) created by the ionizing radiation impinging on the cavity walls. The velocity range from -4 to 0.5km/s is dominated by emission from the clumpy molecular cloud, and the [OI], [CII], and high-J CO lines are excited in PDRs on clump surfaces that are illuminated by the central stars. Modelling the line emission in the different velocity ranges with the KOSMA-τ code constrains a radiation field χ of a few times 104 and densities n of a few times 104cm–3. Considering self-absorption of the [OI] line results in higher densities (up to 106cm–3) only for the gas component seen at high blue- and red velocities. We thus confirm the scenario found in other studies that the emission of these lines can be explained by a two-phase PDR, but attribute the high-density gas to the high-velocity component only. The dark lane has a mass of ∼275M and shows a velocity difference of ∼1.4km/s along its projected length of ∼1pc, determined from H13CO+ 1-0 mapping.Its nature depends on the geometry and can be interpreted as a massive accretion flow (infall rate of ∼2.5x10–4M/yr), or the remains of it, linked to S106IR/FIR. The most likely explanation is that the binary system is at a stage of its evolution where gas accretion is counteracted by the stellar winds and radiation, leading to the very complex observed spatial and kinematic emission distribution of the various tracers.

Abstract Copyright: © ESO 2018

Journal keyword(s): accretion, accretion disks - ISM: atoms - ISM: molecules - ISM: clouds - HII regions - photon-dominated region (PDR)

CDS comments: Paragraph 5.3 Cores S20 to S24 not in SIMBAD.

Simbad objects: 7

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Number of rows : 7

N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2019
1 NAME Orion Bright Bar reg 05 35 22.30 -05 24 33.0           ~ 687 0
2 NAME Mon R2 HII 06 07 46.6 -06 22 59           ~ 631 2
3 NAME SH 2-106 FIR IR 20 27 25.4 +37 22 48           ~ 48 0
4 SH 2-106 HII 20 27 26.8 +37 22 49           ~ 404 2
5 NAME Cyg X Cld 20 28 41 +41 10.2           ~ 585 1
6 EM* MWC 349A Em* 20 32 45.518 +40 39 36.62           ~ 140 0
7 GRS G081.70 +00.50 SFR 20 39 01.6 +42 19 38           O4.5 927 0

    Equat.    Gal    SGal    Ecl

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