On the feedback from super
stellar clusters. I. The structure of giant HII regions and HII
galaxies.
Guillermo
Tenorio-Tagle, Instituto Nacional de Astrofísica Óptica y
Electrónica, AP 51, 72000 Puebla, México, gtt@inaoep.mxgtt@iaa.es
Casiana
Muñoz-Tuñón, Instituto de
Astrofísica de Canarias, E 38200 La Laguna, Tenerife, Spain, cmt@ll.iac.es
Enrique Pérez, Instituto de Astrofísica de
Andalucía (CSIC), Camino bajo de Huetor 50, E 18080 Granada,
Spain, eperez@iaa.es
Sergej Silich, Instituto Nacional de Astrofísica Óptica y
Electrónica, AP 51, 72000 Puebla, México, silich@inaoep.mx
Eduardo Telles, Observatório Nacional, Rua José Cristino
77, 20921-400, Rio de Janeiro, Brazil, etelles@on.br
Abstract. We review the
structural properties of giant extragalactic HII regions and HII
galaxies based on two dimensional hydrodynamic calculations, and
propose an evolutionary sequence that accounts for their observed
detailed structure. The model assumes a massive and young stellar
cluster surrounded by a large collection of clouds. These are thus
exposed to the most important star-formation feedback
mechanisms: photoionization and the cluster wind. The models show
how the two feedback mechanisms compete with each other in the
disruption of clouds and lead to two different hydrodynamic solutions:
The storage of clouds into a long lasting ragged shell that inhibits
the expansion of the thermalized wind, and the steady filtering of the
shocked wind gas through channels carved within the cloud stratum. Both
solutions are here claimed to be concurrently at work in giant HII
regions and HII galaxies, causing their detailed inner structure. This
includes multiple large-scale shells, filled with an X-ray emitting
gas, that evolve to finally merge with each other, giving the
appearance of shells within shells. The models also show how
the inner filamentary structure of the giant superbubbles
is largely enhanced with matter ablated from clouds and how cloud
ablation proceeds within the original cloud stratum. The calculations
point at the initial contrast density between the cloud and the
intercloud media as the factor that defines which of the two feedback
mechanisms becomes dominant throughout the evolution. Animated version
of the models presented can be found at
http://www.iaa.csic.es/~eperez/ssc/ssc.html
Astrophysical Journal 2006, vol.
643, p. 186. Full
manuscript in PDF format
(1.11 MB).
The animations corresponding to the different cases described in this
work can be found here,
in the form of animated GIF files.
Case
C. Cloud density, nc=1000 cm-3.
Photoionization plus stellar wind.
Full frame (194 pc x 194
pc) 2D animation
of density and temperature evolution. (4.1MB)
A slower version (0.2s delay
between frames).
(4.1MB)