Line formation in CO5BOLD simulation of red supergiant

A. Chiavassa, B. Plez, E. Josselin,*

B. Freytag**

*GRAAL, Montpellier, France

**LANL, USA; Uppsala University, Sweden

CO5BOLD Workshop, June 2006

RSG have complex spectra …

- strong molecular bands (TiO ...)

- large “macroturbulence” (~15 km s-1)

continuum poorly defined, spectrum synthesis is difficult ...

1D does not work for RSGs !

Post-Processing

τλ ijk = χ ijk Tijk , ρijk ,λ ⋅ 1− v ijk / c( )( )1

k

∑ ρijkδzijk

Iλij = Bλ Tijk( )k∑ ⋅exp −τ λijk( )δτ λijk

avec

6.3 sec / λ

(3153 rayons)

R = λ/λ = c/v 85000

~ 30 h / 1000 A

interpolation of ijk

exponential

Strongline

Pseudo-ContinuumLine

Very Strong Line (Fe I)

Very Strong Line

Weak Line (Si I) Strong Line (Ca I)

Pseduo - Continuum

Pseudo-ContinuumLine

Strongline

Weak Line

1

43

2

Pseudo Continuum line

1

3 4

2

Strong line

Problems

No microturbolence

Additional microturbolence

1.5 km/s

Additional microturbolence

5 km/s

Conclusions

• Intensity comes from different regions at different depth

• Velocity does not behave the same at different depth

• 3D models do not reproduce high and low excitation line

Needs

• Increase model resolution to 5003 points

• Increase model temperature at least to 3600K

• non-grey radiation transport