Leaky HII regions and helium ionization in the Reynolds layer

K  Wood; J S  Mathis

Leaky HII regions and helium ionization in the Reynolds layer

K Wood, J S Mathis

School of Physics and Astronomy

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

Abstract

In the Milky Way's diffuse ionized gas, helium is observed to be underionized relative to hydrogen, implying ionization by a softer radiation field than typical of H (II) regions. We construct 3D photoionization models of the diffuse ionized gas and show that the ionizing spectra escaping from leaky H it regions can provide a solution to the He+/H+ problem. Depending on the spectral type of the ionizing source(s) and the fractional leakage from the H it region, we find that leaky spectra are harder and have their He-ionizing photon luminosity supressed. Such spectra yield a reduced He+/H+ fraction and increased heating compared to normal stellar spectra.

Original language	English
Title of host publication	HOW DOES THE GALAXY WORK?
Editors	EJ Alfaro, E Perez, J Franco
Place of Publication	DORDRECHT
Publisher	Springer
Pages	83-87
Number of pages	5
ISBN (Print)	1-4020-2619-6
Publication status	Published - 2004
Event	International Conference on How Does the Galaxy Work - Granada Duration: 23 Jun 2003 → 27 Jun 2003

Conference

Conference	International Conference on How Does the Galaxy Work
City	Granada
Period	23/06/03 → 27/06/03

Cite this

@inproceedings{05dc797c79bf4dd9bdd287a4575decca,

title = "Leaky HII regions and helium ionization in the Reynolds layer",

abstract = "In the Milky Way's diffuse ionized gas, helium is observed to be underionized relative to hydrogen, implying ionization by a softer radiation field than typical of H (II) regions. We construct 3D photoionization models of the diffuse ionized gas and show that the ionizing spectra escaping from leaky H it regions can provide a solution to the He+/H+ problem. Depending on the spectral type of the ionizing source(s) and the fractional leakage from the H it region, we find that leaky spectra are harder and have their He-ionizing photon luminosity supressed. Such spectra yield a reduced He+/H+ fraction and increased heating compared to normal stellar spectra.",

author = "K Wood and Mathis, \{J S\}",

year = "2004",

language = "English",

isbn = "1-4020-2619-6",

pages = "83--87",

editor = "EJ Alfaro and E Perez and J Franco",

booktitle = "HOW DOES THE GALAXY WORK?",

publisher = "Springer",

address = "Netherlands",

note = "International Conference on How Does the Galaxy Work ; Conference date: 23-06-2003 Through 27-06-2003",

}

TY - GEN

T1 - Leaky HII regions and helium ionization in the Reynolds layer

AU - Wood, K

AU - Mathis, J S

PY - 2004

Y1 - 2004

N2 - In the Milky Way's diffuse ionized gas, helium is observed to be underionized relative to hydrogen, implying ionization by a softer radiation field than typical of H (II) regions. We construct 3D photoionization models of the diffuse ionized gas and show that the ionizing spectra escaping from leaky H it regions can provide a solution to the He+/H+ problem. Depending on the spectral type of the ionizing source(s) and the fractional leakage from the H it region, we find that leaky spectra are harder and have their He-ionizing photon luminosity supressed. Such spectra yield a reduced He+/H+ fraction and increased heating compared to normal stellar spectra.

AB - In the Milky Way's diffuse ionized gas, helium is observed to be underionized relative to hydrogen, implying ionization by a softer radiation field than typical of H (II) regions. We construct 3D photoionization models of the diffuse ionized gas and show that the ionizing spectra escaping from leaky H it regions can provide a solution to the He+/H+ problem. Depending on the spectral type of the ionizing source(s) and the fractional leakage from the H it region, we find that leaky spectra are harder and have their He-ionizing photon luminosity supressed. Such spectra yield a reduced He+/H+ fraction and increased heating compared to normal stellar spectra.

M3 - Conference contribution

SN - 1-4020-2619-6

SP - 83

EP - 87

BT - HOW DOES THE GALAXY WORK?

A2 - Alfaro, EJ

A2 - Perez, E

A2 - Franco, J

PB - Springer

CY - DORDRECHT

T2 - International Conference on How Does the Galaxy Work

Y2 - 23 June 2003 through 27 June 2003

ER -

Leaky HII regions and helium ionization in the Reynolds layer

Abstract

Conference

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