C.D.S. - SIMBAD4 rel 1.7 - 2021.03.05CET18:41:20

2017ApJ...843..149S - Astrophys. J., 843, 149-149 (2017/July-2)

The validity of 21 cm spin temperature as a kinetic temperature indicator in atomic and molecular gas.


Abstract (from CDS):

The gas kinetic temperature (TK) of various interstellar environments is often inferred from observations that can deduce level populations of atoms, ions, or molecules using spectral line observations; H I 21 cm is perhaps the most widely used, and has a long history. Usually the H I 21 cm line is assumed to be in thermal equilibrium and the populations are given by the Boltzmann distribution. A variety of processes, many involving Lyα, can affect the 21 cm line. Here we show how this is treated in the spectral simulation code Cloudy, and present numerical simulations of environments where this temperature indicator is used, with a detailed treatment of the physical processes that determine level populations within H0. We discuss situations where this temperature indicator traces TK, cases where it fails, as well as the effects of Lyα pumping on the 21 cm spin temperature. We also show that the Lyα excitation temperature rarely traces the gas kinetic temperature.

Abstract Copyright: © 2017. The American Astronomical Society. All rights reserved.

Journal keyword(s): ISM: clouds - radiative transfer - radio lines: galaxies - radio lines: galaxies

Simbad objects: 5

goto Full paper

goto View the reference in ADS

Number of rows : 5

N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
1 NAME Trapezium Cluster As* 05 35 16.5 -05 23 14           ~ 1499 1
2 NAME Ori Region reg 05 35 17.30 -05 23 28.0           ~ 500 0
3 M 42 HII 05 35 17.3 -05 23 28           ~ 3777 0
4 NGC 6618 OpC 18 20 47 -16 10.3           ~ 1508 0
5 NAME Orion's Veil HI ~ ~           ~ 38 0

    Equat.    Gal    SGal    Ecl

To bookmark this query, right click on this link: simbad:objects in 2017ApJ...843..149S and select 'bookmark this link' or equivalent in the popup menu


© Université de Strasbourg/CNRS

    • Contact