2009ApJ...706.1036G


C.D.S. - SIMBAD4 rel 1.7 - 2021.06.17CEST04:15:54

2009ApJ...706.1036G - Astrophys. J., 706, 1036-1053 (2009/December-1)

Formation of an o-star cluster by hierarchical accretion in G20.08-0.14 N.

GALVAN-MADRID R., KETO E., ZHANG Q., KURTZ S., RODRIGUEZ L.F. and HO P.T.P.

Abstract (from CDS):

Spectral line and continuum observations of the ionized and molecular gas in G20.08-0.14 N explore the dynamics of accretion over a range of spatial scales in this massive star-forming region. Very Large Array (VLA) observations of NH3 at 4'' angular resolution show a large-scale (0.5 pc) molecular accretion flow around and into a star cluster with three small, bright H II regions. Higher resolution (0".4) observations with the Submillimeter Array in hot core molecules (CH3CN, OCS, and SO2) and the VLA in NH3 show that the two brightest and smallest H II regions are themselves surrounded by smaller scale (0.05 pc) accretion flows. The axes of rotation of the large- and small-scale flows are aligned, and the timescale for the contraction of the cloud is short enough, 0.1 Myr, for the large-scale accretion flow to deliver significant mass to the smaller scales within the star formation timescale. The flow structure appears to be continuous and hierarchical from larger to smaller scales. Millimeter radio recombination line (RRL) observations at 0".4 angular resolution indicate rotation and outflow of the ionized gas within the brightest H II region (A). The broad recombination lines and a continuum spectral energy distribution (SED) that rises continuously from cm to mm wavelengths, are both characteristic of the class of H II regions known as "broad recombination line objects." The SED indicates a density gradient inside this H II region, and the RRLs suggest supersonic flows. These observations are consistent with photoevaporation of the inner part of the rotationally flattened molecular accretion flow. We also report the serendipitous detection of a new NH3(3,3) maser.

Abstract Copyright:

Journal keyword(s): H II regions - ISM: individual: G20.08-0.14 - masers - stars: formation

Simbad objects: 23

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Number of rows : 23

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 NAME W 3 OH HII 02 27 04.1 +61 52 22           ~ 963 2
2 GAL 174.20-00.08 Cld 05 30 45.9 +33 47 56           ~ 185 2
3 NAME OMC1 Ridge reg 05 35 13.4 -05 23 07           ~ 124 0
4 NAME Orion Core ? 05 35 14.5 -05 22 30           ~ 180 0
5 IRAS 05358+3543 mul 05 39 10.4 +35 45 19           ~ 139 1
6 NAME SH 2-233 IR Cl* 05 39 10.4 +35 45 19           ~ 93 0
7 3C 273 BLL 12 29 06.6996828061 +02 03 08.598846466   13.05 14.830 14.11   ~ 5451 1
8 NAME Sgr B2 (North) Rad 17 47 20.2 -28 22 21           ~ 562 1
9 W 31c HII 18 10 29.1 -19 56 05           ~ 310 0
10 [HH81] G20.1-0.1 B HII 18 28 10.31 -11 28 48.6           ~ 5 0
11 [WC89] 020.08-0.14B HII 18 28 10.360 -11 28 48.02           ~ 4 0
12 OH 20.1 -0.1 SFR 18 28 10.3918 -11 28 44.164           ~ 108 0
13 [HH81] G20.1-0.1 A HII 18 28 10.44 -11 28 48.9           ~ 6 0
14 RAFGL 5491 mul 18 28 10.7 -11 29 01           ~ 45 0
15 GAL 024.78+00.08 HII 18 36.2 -07 13           ~ 75 0
16 GAL 028.20-00.04 HII 18 42 58.2 -04 14 05           ~ 52 0
17 GAL 029.96-00.02 Y*O 18 46 03.7 -02 39 21           ~ 337 1
18 W 51e2 Rad 19 23 43.90 +14 30 34.8           ~ 189 0
19 MSX6C G059.7831+00.0648 Y*O 19 43 11.21664 +23 44 03.9696           ~ 130 0
20 IRAS 19410+2336 SFR 19 43 11.5 +23 44 06           ~ 144 0
21 [MBS2007c] CygX-N44 Rad 20 39 01.01 +42 22 50.2           ~ 367 0
22 LDN 1157 DNe 20 39 06.4 +68 02 13           ~ 511 0
23 3C 454.3 Bla 22 53 57.74798 +16 08 53.5611   16.57 16.10 15.22   ~ 2584 2

    Equat.    Gal    SGal    Ecl

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