2011A&A...527A..62B


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.08CEST03:49:24

2011A&A...527A..62B - Astronomy and Astrophysics, volume 527A, 62-62 (2011/3-1)

Triggered star formation at the borders of the HII region Sh 2-217.

BRAND J., MASSI F., ZAVAGNO A., DEHARVENG L. and LEFLOCH B.

Abstract (from CDS):

This paper is part of our ongoing study of star formation at the borders of Galactic HII regions. In this paper, we report our observations and analysis of Sharpless 217 (Sh 2-217). We study the stars and gas in and around HII regions to see if the various physical parameters derived from the data (such as column densities, masses, sizes, and timescales) are consistent with the predictions of a simple model of the collect-and-collapse mechanism. This should indicate whether stars forming in molecular gas at the borders of the HII regions could have been triggered by the expansion of the ionized gas. We observed the emission of various molecules and transitions towards Sh 2-217, and obtained both near-infrared photometry in the H and K bands, and near-infrared images in [FeII] and H2 narrow-band filters of the stars in a molecular condensation at the edge of the HII region, where an UC HII region is also located. For the atomic and ionized hydrogen gas, we used literature data. Several molecular condensations are found on the borders of Sh 2-217 and both behind and in front of the ionized emission. We find signs of star formation (an UC Hii region, outflows, and water masers). The masses of the larger molecular condensations, derived from 13CO-data, are >330-1100M, while smaller clumps or cores within them have up to several tens of solar masses. The morphology of the atomic and molecular gas associated with Sh 2-217, especially the condensations of molecular gas on its border, and the presence of star forming activity within them, is strongly indicative of it being the result of star formation triggered by the expansion of the ionized region, following the collect-and-collapse scenario. Application of a simple model illustrates that the present radii of both Sh 2-217 and the UC HII region, the masses of the condensations, and the timescales needed to sweep up these amounts of gas and allow massive stars to form in them, are consistent with the model predictions. We show that it is highly plausible that the expansion of Sh 2-217 has swept-up the ambient interstellar medium, and that it has taken about 4Myr to reach its present radius. About 1Myr ago, the most massive gas condensation became unstable and produced a cluster of stars. The most massive of these stars gave rise to the UC HII region, which took about 0.5Myr to reach its present size.

Abstract Copyright:

Journal keyword(s): stars: formation - ISM: clouds - ISM: individual objects: Sh 2-217

VizieR on-line data: <Available at CDS (J/A+A/527/A62): table7.dat>

Status at CDS:   All or part of tables of objects could be ingested in SIMBAD with priority 2.

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 - 2020
#notes
1 3C 48 QSO 01 37 41.2995845985 +33 09 35.079126038   16.62 16.20     ~ 2496 2
2 NAME W 3 OH HII 02 27 04.1 +61 52 22           ~ 941 2
3 NAME Per Arm PoG 03 30 +45.0           ~ 1247 0
4 4C 50.11 QSO 03 59 29.74726473 +50 57 50.1615765           ~ 395 1
5 SH 2-212 HII 04 40 36.50 +50 27 44.3           ~ 88 2
6 LBN 159.33+02.55 HII 04 56 05.5 +47 22 33           ~ 66 0
7 RAFGL 5133 IR 04 58 29.7 +47 58 28           ~ 19 0
8 LS V +47 24 * 04 58 45.3394503258 +47 59 56.122840372 11.14 11.74 11.32     O9.5V 25 0
9 LBN 159.17+03.33 HII 04 58 45.70 +47 59 36.0           ~ 77 2
10 SNR G160.8+02.6 SNR 05 01 00.000 +46 40 00.00           ~ 191 0
11 NVSS J050237+413919 Rad 05 02 37.98820882 +41 39 19.3479360           ~ 8 1
12 NAME OMC1 Ridge reg 05 35 13.4 -05 23 07           ~ 123 0
13 NAME Orion-KL SFR 05 35 14.16 -05 22 21.5           ~ 2001 1
14 GRS G308.60 +00.60 HII 13 39.9 -61 45           ~ 93 0
15 RCW 82 HII 13 59.3 -61 27           ~ 30 0
16 SH 2-3 HII 17 12.4 -38 28           ~ 159 1
17 NAME Sgr B2 MoC 17 47 20.4 -28 23 07           ~ 1909 1
18 W 49n HII 19 10 13.2 +09 06 12           ~ 411 3
19 W 51 SNR 19 23 50 +14 06.0           ~ 1143 1
20 SH 2-104 HII 20 24 37 +38 31.9           ~ 90 0
21 GRS G081.70 +00.50 SFR 20 39 01.6 +42 19 38           O4.5 944 0

    Equat.    Gal    SGal    Ecl

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2020.07.08-03:49:24

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