Outflow-Confined H II Regions. I. First Signposts of Massive Star
Formation
K. Tanaka, J. Tan, and Y. Zhang. (2015)cite arxiv:1509.06754Comment: 18 pages, 17 figures, submitted to ApJ.
Abstract
We present an evolutionary sequence of models of the photoionized disk-wind
outflow around forming massive stars based on the Core Accretion model. The
outflow is expected to be the first structure to be ionized by the protostar
and can confine the expansion of the H II region, especially in lateral
directions in the plane of the accretion disk. The ionizing luminosity
increases as Kelvin-Helmholz contraction proceeds, and the H II region is
formed when the stellar mass reaches $\sim\:10$ - $20\:M_ødot$ depending on
the initial cloud core properties. Although some part of outer disk surface
remains neutral due to shielding by the inner disk and the disk wind, almost
the whole of the outflow is ionized in $10^3$ - $10^4\:yr$ after initial
H II region formation. Having calculated the extent and temperature structure
of the H II region within the immediate protostellar environment, we then make
predictions for the strength of its free-free continuum and recombination line
emission. The free-free radio emission from the ionized outflow has a flux
density of $\sim5$ - $50\:(\nu/GHz)^p\rm\:mJy\:kpc^2$ with a spectral
index $p = 0.6 - 0.9$, and the apparent size is typically $\sim\:1000\:AU$
at 1 GHz. The H40$\alpha$ line profile has a width of about $100\:\rm
km\:s^-1$. These properties of our model are consistent with observed radio
winds and jets around forming massive protostars.
Description
[1509.06754] Outflow-Confined H II Regions. I. First Signposts of Massive Star Formation
%0 Generic
%1 tanaka2015outflowconfined
%A Tanaka, Kei E. I.
%A Tan, Jonathan C.
%A Zhang, Yichen
%D 2015
%K HII expansion outflowing regions
%T Outflow-Confined H II Regions. I. First Signposts of Massive Star
Formation
%U http://arxiv.org/abs/1509.06754
%X We present an evolutionary sequence of models of the photoionized disk-wind
outflow around forming massive stars based on the Core Accretion model. The
outflow is expected to be the first structure to be ionized by the protostar
and can confine the expansion of the H II region, especially in lateral
directions in the plane of the accretion disk. The ionizing luminosity
increases as Kelvin-Helmholz contraction proceeds, and the H II region is
formed when the stellar mass reaches $\sim\:10$ - $20\:M_ødot$ depending on
the initial cloud core properties. Although some part of outer disk surface
remains neutral due to shielding by the inner disk and the disk wind, almost
the whole of the outflow is ionized in $10^3$ - $10^4\:yr$ after initial
H II region formation. Having calculated the extent and temperature structure
of the H II region within the immediate protostellar environment, we then make
predictions for the strength of its free-free continuum and recombination line
emission. The free-free radio emission from the ionized outflow has a flux
density of $\sim5$ - $50\:(\nu/GHz)^p\rm\:mJy\:kpc^2$ with a spectral
index $p = 0.6 - 0.9$, and the apparent size is typically $\sim\:1000\:AU$
at 1 GHz. The H40$\alpha$ line profile has a width of about $100\:\rm
km\:s^-1$. These properties of our model are consistent with observed radio
winds and jets around forming massive protostars.
@misc{tanaka2015outflowconfined,
abstract = {We present an evolutionary sequence of models of the photoionized disk-wind
outflow around forming massive stars based on the Core Accretion model. The
outflow is expected to be the first structure to be ionized by the protostar
and can confine the expansion of the H II region, especially in lateral
directions in the plane of the accretion disk. The ionizing luminosity
increases as Kelvin-Helmholz contraction proceeds, and the H II region is
formed when the stellar mass reaches $\sim\:10$ - $20\:M_\odot$ depending on
the initial cloud core properties. Although some part of outer disk surface
remains neutral due to shielding by the inner disk and the disk wind, almost
the whole of the outflow is ionized in $10^3$ - $10^4\:{\rm yr}$ after initial
H II region formation. Having calculated the extent and temperature structure
of the H II region within the immediate protostellar environment, we then make
predictions for the strength of its free-free continuum and recombination line
emission. The free-free radio emission from the ionized outflow has a flux
density of $\sim5$ - $50\:(\nu/{\rm GHz})^p{\rm\:mJy\:kpc^2}$ with a spectral
index $p = 0.6 - 0.9$, and the apparent size is typically $\sim\:1000\:\rm AU$
at 1 GHz. The H40$\alpha$ line profile has a width of about $100\:{\rm
km\:s^{-1}}$. These properties of our model are consistent with observed radio
winds and jets around forming massive protostars.},
added-at = {2015-09-24T10:26:37.000+0200},
author = {Tanaka, Kei E. I. and Tan, Jonathan C. and Zhang, Yichen},
biburl = {https://www.bibsonomy.org/bibtex/25c81d7645b79b1260cb9388e6806edeb/miki},
description = {[1509.06754] Outflow-Confined H II Regions. I. First Signposts of Massive Star Formation},
interhash = {a18c9d50fa451af0a5c67e355cd644f6},
intrahash = {5c81d7645b79b1260cb9388e6806edeb},
keywords = {HII expansion outflowing regions},
note = {cite arxiv:1509.06754Comment: 18 pages, 17 figures, submitted to ApJ},
timestamp = {2015-09-24T10:26:37.000+0200},
title = {Outflow-Confined H II Regions. I. First Signposts of Massive Star
Formation},
url = {http://arxiv.org/abs/1509.06754},
year = 2015
}