3-D Radiative Transfer in Clumped Hot Star Winds

Surlan et al. 1202.4787Surlan et al. 1202.4494

Reporter: Wei SunMar. 5th, 2012

Why hot star winds?Mass loss plays an important role in

the stellar evolution (Meynet et al. 1994),the affection to the interstellar environment:

chemical, momentum, and mechanical feedback;

Typical valuesmass-loss rate ;terminal velocity ;mechanical energy

;

β-velocity law:

Mass-loss rate, mass-loss rate, mass-loss rate!diagnostics: fitting the spectroscopic observations via line-

blanketed, non-LTE atmosphere models (e.g., CMFGEN Hillier & Miller 1998, PoWR Gräfener et al. 2002, FASTWIND Puls et al. 2005), “density squared” vs. “radial optical depth”recombination lines (e.g., Hα line, Puls et al, 1996); free-free continuum emission in radio band; UV resonance-line absorption (e.g., C IV λλ1548,

1551, P V λλ1118, 1128)influence from X-rays: changes of the ionization/excitation

balance by Auger effect

the intrinsic instability of the line-driven winds (Lucy & White, 1980);

stochastic variability (Eversberg et al., 1998);the X-ray line formation favors the inhomogeneities

of the stellar winds (Oskinova et al., 2006);a combine optical/IR/radio analysis derived a lower

mass-loss rate comparing to Hα’s result (Puls et al., 2006):

the P V problem (Fullerton, Massa, & Prinja, 2006);

Why clumping winds?

ζ Pup, Lépine & Moffat, 2008

O VIII line in ζ Ori (Oskinova et al., 2006)

Fullerton, Massa, & Prinja, 2006

Why macro-clumping winds?The mass-loss rate derived from the P-Cygni P V

resonance line is extremely low;

macro- vs. micro-: optical thick vs. thin = porosity vs. clumped;optically thin emission: not influenced vs. enhanced;optically thick emission: reduced vs. not influenced;mass-loss rate: seemly not reduced vs. reduced;

Previous Workfirst attempt: Oskinova et al., 2006;

non-monotonic velocity field: Owocki 2008;

non-void inter-clump medium: Zsargó et al., 2008;

2-D stochastic wind model: Sundqvist et al., 2010;

extended to pseudo-3D: Sundqvist et al., 2011.

Model Descriptionbasic assumptions:

core-halo model: only counts in the line opacity;spherical clumps (radius neither split nor merge

;free parameters:

the average clump separation the clump condensation factor the ICM dilution factor

derived parameter: total mass

filling factor

Radiative TransferCalculate τ

random scattering

Results: clumping separation

Results: on-set radius

Results: non-void ICM

Results: velocity dispersion inside clumps

Results: a doublet

Summarylarger separation: reducing the line strength; The photons can also be scattered in the density

“holes” due to ICM; The strong lines are saturated more;

clumping starts higher in the wind, the absorption near the line center is broader;

The velocity dispersion inside clumps broadens the line widths;

the clumping effects are analogues in the case of resonance doublets.

Clumping lowers the effective opacity.

THANKS!