2017MNRAS.471.4476D -
Mon. Not. R. Astron. Soc., 471, 4476-4487 (2017/November-2)
Molecular clumps photoevaporation in ionized regions.
DECATALDO D., FERRARA A., PALLOTTINI A., GALLERANI S. and VALLINI L.
Abstract (from CDS):
We study the photoevaporation of molecular clumps exposed to a UV radiation field including hydrogen-ionizing photons (hν > 13.6 eV) produced by massive stars or quasars. We follow the propagation and collision of shock waves inside clumps and take into account self-shielding effects, determining the evolution of clump size and density with time. The structure of the ionization-photodissociation region is obtained for different initial clump masses (M = 0.01-104 M☉) and impinging fluxes (G0 = 102-105 in units of the Habing flux). The cases of molecular clumps engulfed in the H II region of an OB star and clumps carried within quasar outflows are treated separately. We find that the clump undergoes in both cases an initial shock-contraction phase and a following expansion phase, which lets the radiation penetrate in until the clump is completely evaporated. Typical evaporation time-scales are ≃0.01 Myr in the stellar case and 0.1 Myr in the quasar case, where the clump mass is 0.1 M☉ and 103 M☉, respectively. We find that clump lifetimes in quasar outflows are compatible with their observed extension, suggesting that photoevaporation is the main mechanism regulating the size of molecular outflows.
Abstract Copyright:
© 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society
Journal keyword(s):
ISM: clouds - ISM: evolution - photodissociation region (PDR) - quasars: general - quasars: general
Simbad objects:
11
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