Long-Wavelength, Free-Free Spectral Energy Distributions from Porous Stellar Winds


Richard Ignace

East Tennessee State University

The influence of macroclumps for free-free spectral energy distributions
(SEDs) of ionized winds is considered. The goal is to emphasize
distinctions between microclumping and macroclumping effects.
Microclumping can alter SED slopes and flux levels if the volume
filling factor of the clumps varies with radius; however, the
modifications are independent of the clump geometry. To what extent
does macroclumping alter SED slopes and flux levels? In addressing
the question, two specific types of macroclump geometries are
explored: shell fragments (``pancake''-shaped) and spherical clumps.
Analytic and semi-analytic results are derived in the limiting case
that clumps never obscure one another. Numerical calculations based
on a porosity formalism is used when clumps do overlap. Under the
assumptions of a constant expansion, isothermal, and fixed ionization
wind, the fragment model leads to results that are essentially
identical to the microclumping result. Mass-loss rate determinations
are not affected by porosity effects for shell fragments. By
contrast, spherical clumps can lead to a reduction in long-wavelength
fluxes, but the reductions are only significant for extreme volume
filling factors.

Reference: to appear in MNRAS
Status: Manuscript has been accepted

Weblink: http://arxiv.org/abs/1601.06715

Comments:

Email: ignace@etsu.edu