2007ApJ...664..915B


Query : 2007ApJ...664..915B

2007ApJ...664..915B - Astrophys. J., 664, 915-927 (2007/August-1)

3He in the Milky Way interstellar medium: ionization structure.

BANIA T.M., BALSER D.S., ROOD R.T., WILSON T.L. and LAROCQUE J.M.

Abstract (from CDS):

The cosmic abundance of the 3He isotope has important implications for many fields of astrophysics. We are using the 8.665 GHz hyperfine transition of 3He+ to determine the 3He/H abundance in Milky Way H II regions and planetary nebulae. This is one in a series of papers in which we discuss issues involved in deriving accurate 3He/H abundance ratios from the available measurements. Here we describe the ionization correction we use to convert the 3He+/H+ abundance, y+3, to the 3He/H abundance, y3. In principle the nebular ionization structure can significantly influence the y3 derived for individual sources. We find that in general there is insufficient information available to make a detailed ionization correction. Here we make a simple correction and assess its validity. The correction is based on radio recombination line measurements of H+ and 4He+, together with simple core-halo source models. We use these models to establish criteria that allow us to identify sources that can be accurately corrected for ionization and those that cannot. We argue that this effect cannot be very large for most of the sources in our observational sample. For a wide range of models of nebular ionization structure we find that the ionization correction factor varies from 1 to 1.8. Although larger corrections are possible, there would have to be a conspiracy between the density and ionization structure for us to underestimate the ionization correction by a substantial amount.

Abstract Copyright:

Journal keyword(s): ISM: H II Regions - ISM: Abundances - Radio Lines: ISM

CDS comments: G133.8 = W 3N, G1.1 = NAME SGR D

Simbad objects: 33

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Number of rows : 33
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 IC 1795 HII 02 25 43.5 +62 06 13           ~ 234 0
2 NAME W 3 North HII 02 26 51.14 +62 15 47.2           ~ 90 0
3 W 3 MoC 02 27 04.10 +61 52 27.1           ~ 987 3
4 NAME Heart Nebula HII 02 32.7 +61 27           ~ 295 1
5 4C 32.14 QSO 03 36 30.10760600 +32 18 29.3422210     17.50 16.6   ~ 598 1
6 NGC 1491 HII 04 03 15.9 +51 18 54           ~ 109 1
7 SH 2-209 HII 04 11 06.7 +51 09 44           ~ 94 0
8 SH 2-212 HII 04 40 36.50 +50 27 44.3           ~ 93 2
9 LBN 784 HII 05 13 25.5 +37 27 01           ~ 74 0
10 M 42 HII 05 35 17.3 -05 23 28           ~ 3853 0
11 SH 2-235 B HII 05 40 52.366 +35 41 29.43   17       ~ 175 1
12 SH 2-235 HII 05 41.1 +35 50           ~ 199 0
13 NGC 2175 OpC 06 09 39 +20 29.2   7.0 6.8     ~ 250 3
14 NAME Rosette Nebula HII 06 32 26.76 +04 47 37.1           ~ 465 1
15 NGC 2467 HII 07 52 18 -26 25.7           ~ 178 1
16 NAME Galactic Center gam 17 45 39.60213 -29 00 22.0000           ~ 12535 0
17 NAME Sgr B2 HII F HII 17 47 20.165 -28 23 04.77           ~ 19 0
18 NAME Sgr B2 MoC 17 47 20.4 -28 23 07           ~ 2049 1
19 NAME Sgr D MoC 17 48 41.75 -28 01 45.0           ~ 126 1
20 SNR G006.4-00.1 SNR 18 01 22.7 -23 17 20           ~ 680 1
21 SH 2-45 HII 18 20 21.2 -16 13 37           ~ 29 0
22 NAME M 17S HII 18 20 25.1 -16 11 37           ~ 23 1
23 NAME M 17 North MoC 18 20 40.19 -16 09 29.0           ~ 43 0
24 NGC 6618 OpC 18 20 47 -16 10.3           ~ 1531 0
25 SNR G030.8-00.0 SNR 18 47 32 -01 56.5           ~ 475 0
26 LBN 040.46+02.46 HII 18 56.4 +07 48   12.16 11.66     ~ 22 0
27 W 49 SFR 19 10 20 +09 07.7           ~ 530 1
28 W 51 SNR 19 23 50 +14 06.0           ~ 1197 1
29 LBN 063.10+00.46 HII 19 49 11.7 +26 51 36   14.60 13.63     ~ 53 0
30 NGC 7027 PN 21 07 01.571952 +42 14 10.47120   10.358 8.831 10.157   ~ 2376 1
31 IC 1470 HII 23 05 09.9 +60 14 31   11.5       ~ 168 1
32 NGC 7538 OpC 23 13 37 +61 30.0           ~ 842 0
33 NGC 7635 HII 23 20 48.3 +61 12 06           ~ 163 2

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2021.11.30-01:06:42

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