AGB-dust

This is a subroutine package specifically developed for calculating the dust production by AGB stars with varying C/O abundance ratios as they develop along the AGB and dredge up carbon after each thermal pulse. It solves the equations for dust growth, outflow velocity and temperature stratification in a stationary, spherically symmetric outflow. It is based on a simple outflow model and uses either a simple analytic model for a gray dust temperature stratification in the dust shell (rapid), or it calculates self-consistently temperatures for each dust species by solving the radiative transfer problem in the dust shell and iterating to flux constancy (slow). In that case also the spectrum is calculated.

It considers the following dust species:

• M-stars (oxygen rich):


• olivine: Mg_2xFe_2(1-x)SiO₄   (treated as binary solid solution)
• pyroxene: Mg_xFe_1-xSiO₃   (treated as binary solid solution)
• metallic iron: Fe
• quartz: SiO₂
• corundum: Al₂O₃
• hibonite: CaAl₁₂O₁₉
• spinel: MgAl₂O₄
• magnesio-wüstite: Mg_0.5Fe_0.5O   (treated as binary solid solution)


• C-stars (carbon rich):


• soot: C
• silicon carbide: SiC
• metallic iron: Fe
• magnesium sulfide: MgS

The program is written in FORTRAN77

The details of the dust formation algorithm are essentially described in:

A.S Ferrarotti, H.-P. Gail (2006) Composition and quantities of dust produced by AGB-stars and returned to the interstellar medium. Astronomy & Astrophysics 447, 553-576

but is extended by some further species and in particular considers particle drift.

• mstar.da: Wind model
       N r T v rho P gamma kapH
  =   number, radius, grey temperature, bulk velocity, density, pressure, factor for radiation pressure, flux-averaged opacity
• mstar-a.da: Particle radii
       N r Oli Pyr Qtz Cor Hib Spi Irn Wue Car SiC MgS
  =   number, radius, radius olivine etc. (= 0 if not present)
• mstar-f.da:
       N r T Oli xOli Pyr xPyr Qua Cor Hib Spi Fe Wue xWue Car SiC MgS
  =   number, radius, grey temperature, condensation degree olivine, composition olivine, etc. (= 1D-50 if not present)
• mstar-t.da: Temperatures of species
       N r Tgrau Oli Pyr Qtz Cor Hib Spi Irn Wue Car SiC MgS erH fEd
  =   number, radius, grey temperature, temperature of species (= 0 if not present), flux error, Eddington factor
• mstar-v.da: Drift velocities of species (all species, even if not formed)
       N r T v vOli vPyr vQua vFe vWue vCor vHib vSpi
  =   number, radius, grey temperature, bulk velocity, drift velocities of species
• huel-M.sp: Spectrum, with
       N lam nue bb Fnu Lnue taunue
  =   number, wavelength, frequency, stellar black body, flux(nue), luminosity(nue), optical depth of shell(nue)

Sample programs

• program for oxygen-rich stars: test-alca.f  (7.2 kB)


• program for carbon-rich stars: test-car.f  (7.2 kB)

Program files

• subroutines for wind model: d-v0-4.incl  (93 kB)


• subroutines for radiative transfer: s-v4.incl  (55 kB)


• subroutines for simple opacity: op.incl  (2.5 kB)

Input files

• element abundances: abun.txt  (0.2 kB)


• definition of dust species: dustlist.txt  (2.0 kB)


• wavelength grid: lamO.txt  (2.0 kB)


• input parameter: starO.txt  (0.2 kB)  (Sample for a M-star)


• input parameter: starC.txt  (0.2 kB)  (Sample for a C-star)

Files with dust opacities

• silicates: silicate.dat  (5.6 kB)


• SiO₂: SiO2.dat  (46 kB)


• corundum: Al2O3.dat  (7.4 kB)


• hibonite: hibonite.dat  (401 kB)


• spinel: MgAl2O4.dat  (550 kB)


• magnesio-wüstite: Mg05Fe05.dat  (401 kB)


• iron: Fe-ext.dat  (5.5 kB)


• amorphous carbon: amC-ext.dat  (9.3 kB)


• SiC: SiC-ext.dat  (5.8 kB)


• magnesium-sulphide: MgS.dat  (6.2 kB)