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The SIMECA code : modeling the circumstellar environement of Be Stars

The SIMECA code : modeling the circumstellar environement of Be Stars. Anthony Meilland & Philippe Stee. The SIMECA code. Input Parameters. Hydrodynamics : ρ, V r , V Ф , T. Statistical equilibrium n1,…,n7,ne at the LTE. n1,…,n7,ne NLTE (Sobolev escape probabilty). Transfer equation

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The SIMECA code : modeling the circumstellar environement of Be Stars

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  1. The SIMECA code : modeling the circumstellar environement of Be Stars Anthony Meilland & Philippe Stee

  2. The SIMECA code Input Parameters Hydrodynamics : ρ, Vr, VФ, T Statistical equilibrium n1,…,n7,ne at the LTE n1,…,n7,ne NLTE (Sobolev escape probabilty) Transfer equation In the continuum Transfer equation In the lines Transfer equation In the continuum Intensity maps In the continuum Line profiles Spectral Energy Distribution Intensity maps In the lines

  3. 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

  4. An example : αArae

  5. Problems Rotation or expansion? VΦ >> Vr VΦ ~ Vr

  6. Solution : Interferometry VΦ >> Vr VΦ ~ Vr

  7. Parameters estimation Stellar parameters: -Distance (not a problem with Gaïa) -Effective temperature and Stellar Radius from the SED fit up to 1μm • 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 Mass flux and expansion velocity parameters (6 parameters) : -Very difficult to determine -All related to the envelope mass

  8. Envelope mass determination From the IR-Flux

  9. 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)

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