+
Using a grid from Bertelli's isochrones, we input observed
Teff, gravity, and [Fe/H] [t= Teff, lg= alog10(g); cgs units]
and we find out which values of a (age, m (mass), rad (radius)
and vmag (absolute magnitude)
are compatible for a star with the observed values.
IN: t - float Teff (K)
err_t - float Uncertainty in Teff (K)
lg - float logg (g in cm -s^2)
err_lg- float Uncertainty in logg
feh - float [Fe/H] = alog10(NFe/NH)-alog10(NFe/NH)_sun
err_feh- float Uncertainty in [Fe/H] (must be at least 0.25 dex)
logt_in- fltarr(17,73,1800) log10(Teff) as a function of [Fe/H],
log(age[ayr]), Mass/Msun (see below)
logg_in- fltarr(17,73,1800) log10(g) as a function of [Fe/H],
log(age[ayr]), Mass/Msun (see below)
logr_in- fltarr(17,73,1800) log10(radius) as a function of [Fe/H],
log(age[ayr]), Mass/Msun (see below)
vmag_in- fltarr(17,73,1800) Mv as a function of [Fe/H],
log(age[ayr]), Mass/Msun (see below)
OUT: a - fltarr(3) three-elements vector with an estimate
of log(Age[yr]), flanked by a lower an upper
limits ([lowerage,age,upperage]).
m - fltarr(3) three-elements vector with an estimate
of the mass (initial - at birth), flanked by a lower
an upper limits ([lowermass,mass,uppermass]).
rad- fltarr(3) three-elements vector with an estimate
of log10(radius), flanked by a lower an upper
limits ([lowerrad,rad,upperrad]).
Mv-flatrr(3) three-elements vector with an estimate
of Mv , flanked by a lower an upper
limits ([lowerMv,Mv,upperMv]).
KEYWORDS: boundarytouch This keyword returns a non-zero value when
retrieved parameters gets solutions that touch the grid
boundaries - an indication that the solution is likely biased.
NOTE: logt and loggg are the grids read from the file 'bert.xdr'
computed with the routine mkgrid.pro (restore,'bert.xdr')
Example, the Sun: IDL> restore,'bert.xdr'
IDL> get_amrv,5770.,150,4.44,0.1,0.0,0.25,logt,logg,logr,vmag,a,m,r
IDL>print,a
-100000. 7.60000 9.29851 -> so, all we can say it's
likely younger than 2.0 Gyr
IDL>print,m
0.701428 1.08546 1.46949 -> so it's M=1.1 +/- 0.4 Msun
Carlos Allende Prieto, Sep/Dec 2002