Post on 14-Jan-2016
description
The SIMECA code :modeling the circumstellar environement of Be Stars
Anthony Meilland & Philippe Stee
The SIMECA code
Hydrodynamics :ρ, Vr, VФ, T
Statistical equilibriumn1,…,n7,ne at the LTE
n1,…,n7,ne NLTE(Sobolev escape probabilty)
Line profiles
Intensity mapsIn the lines
Intensity mapsIn the continuum
Spectral Energy Distribution
Input Parameters
Transfer equation In the continuum
Transfer equation In the lines
Transfer equationIn the continuum
Input parameters
-Stellar Radius (can depend on latitude)-Effective Temperature (can depend on latitude)-Distance
-Stellar rotational velocity-Rotation law exponent
-Photospheric density
-Polar and equatorial terminal expansion velocity -Expansion velocity latitudinal variation exponent
-Polar and equatorial mass flux-Mass flux latitudinal variation exponent
-Envelope outer radius
-Inclination angle n
An example : α Arae
ProblemsRotation or expansion?
VΦ >> Vr VΦ ~ Vr
Solution : Interferometry
VΦ >> Vr VΦ ~ Vr
Parameters estimation
Inclination angle :
-Degeneracy problem in spectroscopy -First estimation with critical velocity (Vrot≤Vc) -Estimated with interferometry (envelope flattening)
Equatorial disk extension :
-Vsini and Double peak separation with a chosen rotation law (keplerian)-Direct determination with interferometry
Stellar parameters:
-Distance (not a problem with Gaïa)-Effective temperature and Stellar Radius from the SED fit up to 1μm
Mass flux and expansion velocity parameters (6 parameters) :
-Very difficult to determine-All related to the envelope mass
Envelope mass determinationFrom the IR-Flux
sunenv MM 1110 sunenv MM 1010.4
So, what do we need?
-Blue part of the SED ( at least 2 spectral band less than 1μm)=> Stellar parameters
-Absorption lines => Vsini
-Red part of the SED (at least 1 spectral band over 2μm)=> Envelope Mass
-One or more spectral lines with sufficient spectral resolution (R>10000) =>Disk extension (if we also have the Vsini)