2001AJ....121..371B


C.D.S. - SIMBAD4 rel 1.7 - 2019.10.19CEST23:11:09

2001AJ....121..371B - Astron. J., 121, 371-390 (2001/January-0)

VLA high-sensitivity 4He imaging of galactic H II regions.

BALSER D.S., GOSS W.M. and DE PREE C.G.

Abstract (from CDS):

We have carried out 8.3 GHz hydrogen and helium radio recombination line and continuum observations of three Galactic H II regions with the NRAO 140 Foot Telescope and the Very Large Array. These observations measure the spatial variations in the singly ionized helium-to-hydrogen abundance ratio, 4He+/H+ (y+), and probe for any localized enhancements in y+. The three observed regions (W43, NGC 6334A, and K3-50) are morphologically complex, and high-resolution, wide field observations are crucial to measure the helium abundances on scales that would be associated with individual massive stars or clusters of stars. The nearly constant y+ value across the W43 source (y+W43=7.7%±1%) indicates that any ionization correction over the spatial scales investigated is small. Such ionization corrections are important for calculating total abundances of the light element 3He, which is measured in the Galaxy via a singly ionized hyperfine transition. Localized enhancements in the y+ value have been detected in both NGC 6334A (y+=20%±4%) and K3-50A (y+=24%±5%). The 4He abundance results are discussed along with other measurements of the physical properties of these H II regions, such as the kinematics and excitation.

Abstract Copyright:

Journal keyword(s): ISM: H II Regions - ISM: Individual: Alphanumeric: K3-50 - ISM: Individual: NGC Number: NGC 6334 - ISM: Individual: Alphanumeric: W43 - ISM: Abundances - ISM: Kinematics and Dynamics - Radio Emission Lines

CDS comments: NGC 6587 misprint for 6857

Simbad objects: 39

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Number of rows : 39

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2019
#notes
1 IC 1795 HII 02 25 43.5 +62 06 13           ~ 227 0
2 W 3 MoC 02 27 04.10 +61 52 27.1           ~ 942 3
3 M 42 HII 05 35 17.3 -05 23 28           ~ 3658 0
4 NAME Ori A MoC 05 38 -07.1           ~ 2610 0
5 3C 286 Sy1 13 31 08.2885060664 +30 30 32.960825108   17.51 17.25     ~ 3615 1
6 GAL 351.20+00.70 HII 17 20 04.1 -35 56 10           ~ 11 0
7 NAME NGC 6334-IV Cl* 17 20 17 -35 54.9           ~ 40 1
8 [HTK2008] IRN IV-2 Y*O 17 20 17.8 -35 54 53           ~ 13 0
9 [HG83] IRS-IV-4 IR 17 20 18.5 -35 55 15           ~ 4 0
10 [HG83] IRS-IV-1 IR 17 20 18.5 -35 54 05           ~ 5 0
11 NGC 6334A HII 17 20 19.3 -35 54 55           ~ 113 0
12 [HG83] IRS-IV-2 Y*O 17 20 19.3 -35 54 05           ~ 10 0
13 [KRL2007b] 236 AGN 17 20 21.81 -35 52 48.2           ~ 101 0
14 [HTK2008] IRN IV-6 Rad 17 20 23.1 -35 55 27           ~ 6 0
15 GAL 351.31+00.6 HII 17 20 32.6 -35 51 24           ~ 41 0
16 NGC 6334 HII 17 20 51 -36 06.9           ~ 558 0
17 NAME Gal Center reg 17 45 40.04 -29 00 28.1           ~ 11004 0
18 NGC 6618 OpC 18 20 47 -16 10.3           ~ 1455 0
19 SNR G030.8-00.0 SNR 18 47 32 -01 56.5           ~ 423 0
20 NAME W 43 Star Cluster Cl* 18 47 36 -01 56.5           ~ 9 1
21 BBRW W43 (c) Rad 18 47 36.04 -01 56 38.9           O6.5 2 0
22 BBRW W43 (a) Rad 18 47 36.42 -01 55 26.9           ~ 1 0
23 BBRW W43 (d) Rad 18 47 38.49 -01 57 35.3           O6 2 0
24 BBRW W43 (b) Rad 18 47 38.55 -01 56 49.0           O7.5 2 0
25 W 43s Rad 18 47 41.68 -02 00 24.3           ~ 22 0
26 [LDW85] 30.8N FIR 18 48 -01.9           ~ 5 0
27 [DJW84] W49 A HII 19 10 12.93 +09 06 11.9           ~ 28 0
28 [DJW84] W49 M HII 19 10 14.74 +09 06 25.4           ~ 8 0
29 W 49a SFR 19 10 15.7 +09 06 05           ~ 255 2
30 CTB 82 Mas 20 01.7 +33 33           ~ 36 0
31 NAME K 3-50A HII 20 01 45.6 +33 32 42           ~ 73 0
32 W 58a HII 20 01 45.8 +33 32 43           ~ 276 4
33 NGC 6857 HII 20 01 47.75 +33 31 38.2           ~ 85 3
34 W 58c3 Rad 20 01 53.94 +33 34 16.4           ~ 4 0
35 OH 1959+33 Mas 20 01 54.03 +33 34 14.2           ~ 32 0
36 [W69] C Rad 20 01 54.2 +33 34 15           ~ 15 0
37 W 58c2 Rad 20 01 55.21 +33 34 17.5           ~ 9 0
38 NGC 6888 ISM 20 12 07 +38 21.3   7.44       WN6b(h) 256 1
39 NGC 7027 PN 21 07 01.8 +42 14 10   9.1 10.9     ~ 2301 1

    Equat.    Gal    SGal    Ecl

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2019.10.19-23:11:09

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