Routine for calculating the mass-loss rate of C-type AGB stars

Description:

Here we provide a simple routine in FORTRAN77 for calculating the mass-loss rate of C-type AGB stars as a function of stellar parameters (mass, luminosity, and effective temperature) and carbon excess, based on data from Mattsson et al. 2010, A&A, 509, 14 and Eriksson et al. 2014, A&A, 566, 95. The resulting mass-loss rates are calculated by interpolation between the current stellar mass (M), the effective temperature (T), the stellar luminosity (log(L)) and the carbon excess (C-O). The pulsation parameters are set to Δup = 4.0 and fL=1. This mass-loss routine can also be used when modeling the AGB phase at subsolar metallicities. It can be modified to include other mass-loss formulas or a lower limit for the mass-loss rate.

Validity:

This subroutine is valid for effective temperatures above 2400K and includes models with stellar masses beween 0.75 to 2.0 solar masses. The upper limit of the luminosity depends on the current steller mass and varies between log(L/L☉)=3.85 and log(L/L☉)=4.15.

M < 0.75M☉ is set to M = 0.75M☉
M > 2.00M☉ is set to M = 2.00M☉
T < 2400K is set to T = 2400K
(C-O) > 9.1 is set to (C-O) = 9.1

The mass-loss rate outside the luminosity range of the grid is assumed to scale linearly with luminosity. This may not be appropriate for luminosities that are much higher than the upper luminosity of the model grid. The mass-loss routine includes two flags (CF and LF) that signal if the luminosity or the carbon excess is outside the range of the model grid.
LF is set to -1 if the luminosity is very high and CF is set to -1 if the carbon excess is very low.

Mass-loss routine command lines:

The model data is read in with the line: CALL READCUBES("cgrid.dat").
The mass-loss rate for a specific combination of stellar parameters (M, L, T) and carbon excess (set by the mass fraction of C12, C13, O16 and the initial hydrogen value) is given by the line: MLR=MASSLOSS(MI, M, log(L), T, XC12, XC13, XO16, XHIN, LF, CF), where CF and LF are warning flags. MI, M, log(L), T, XC12, XC13, XO16 and XHIN are real*4 variables and MF and LF are integer variables. The initial mass MI is not used in the current interpolation but is included for implementating alternative mass-loss descriptions.

References

When using the mass-loss routine at solar metallicity please reference Mattsson et al. 2010, A&A, 509, 14 and Eriksson et al. 2014, A&A, 566, 95. When using the mass-loss routine at subsolar metallicity reference Mattsson et al. 2010, A&A, 509, 14, Eriksson et al. 2014, A&A, 566, 95 and Bladh et al. 2019, A&A, 623, 119.

File Summary: mlr_cstar.zip

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 FileName               Explanations
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mlrmod_cstar.f      Mass-loss routine in FORTRAN77
mlrmod_cstar.inc    Mass-loss routine module
cgrid.dat           The input data, based on the model grids in Mattsson et al. 2010, A&A, 509, 14 
                    and Eriksson et al. 2014, A&A, 566, 95
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Author's address: sara.bladh@physics.uu.se
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(End)                                        Sara Bladh [Uppsala university, Sweden]     15-May-2019
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