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star.f
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***
SUBROUTINE star(kw,mass,mt,tm,tn,tscls,lums,GB,zpars)
*
*
* Stellar luminosity & evolution time.
* ------------------------------------
*
implicit none
*
integer kw
*
real*8 mass,mt,tm,tn,tscls(20),lums(10),GB(10),zpars(20)
real*8 tgb,tbagb,mch,mcmax,mc1,mc2,mcbagb,dx,am
real*8 lambda,tau,mtc,mass0
parameter(mch=1.44d0)
*
real*8 lzamsf,lzahbf,lzhef
real*8 tbgbf,thookf,tHef,themsf,mcgbf,mcagbf,mcheif,mcgbtf
real*8 ltmsf,lbgbf,lHeIf,lHef,lbagbf,lmcgbf
external lzamsf,lzahbf,lzhef
external tbgbf,thookf,tHef,themsf,mcgbf,mcagbf,mcheif,mcgbtf
external ltmsf,lbgbf,lHeIf,lHef,lbagbf,lmcgbf
*
* Computes the characteristic luminosities at different stages (LUMS),
* and various timescales (TSCLS).
* Ref: P.P. Eggleton, M.J. Fitchett & C.A. Tout (1989) Ap.J. 347, 998.
*
* Revised 27th March 1995 by C. A. Tout
* and 24th October 1995 to include metallicity
* and 13th December 1996 to include naked helium stars
*
* Revised 5th April 1997 by J. R. Hurley
* to include Z=0.001 as well as Z=0.02, convective overshooting,
* MS hook and more elaborate CHeB. It now also sets the Giant
* Branch parameters relevant to the mass of the star.
*
* ------------------------------------------------------------
* Times: 1; BGB 2; He ignition 3; He burning
* 4; Giant t(inf1) 5; Giant t(inf2) 6; Giant t(Mx)
* 7; FAGB t(inf1) 8; FAGB t(inf2) 9; FAGB t(Mx)
* 10; SAGB t(inf1) 11; SAGB t(inf2) 12; SAGB t(Mx)
* 13; TP 14; t(Mcmax)
*
* LUMS: 1; ZAMS 2; End MS 3; BGB
* 4; He ignition 5; He burning 6; L(Mx)
* 7; BAGB 8; TP
*
* GB: 1; effective A(H) 2; A(H,He) 3; B
* 4; D 5; p 6; q
* 7; Mx 8; A(He) 9; Mc,BGB
*
* ------------------------------------------------------------
*
*
mass0 = mass
if(mass0.gt.100.d0) mass = 100.d0
*
if(kw.ge.7.and.kw.le.9) goto 90
if(kw.ge.10) goto 95
*
* MS and BGB times
*
tscls(1) = tbgbf(mass)
tm = MAX(zpars(8),thookf(mass))*tscls(1)
*
* Zero- and terminal age main sequence luminosity
*
lums(1) = lzamsf(mass)
lums(2) = ltmsf(mass)
*
* Set the GB parameters
*
GB(1) = MAX(-4.8d0,MIN(-5.7d0+0.8d0*mass,-4.1d0+0.14d0*mass))
GB(1) = 10.d0**GB(1)
GB(2) = 1.27d-05
GB(8) = 8.0d-05
GB(3) = MAX(3.0d+04,500.d0 + 1.75d+04*mass**0.6d0)
if(mass.le.2.0)then
GB(4) = zpars(6)
GB(5) = 6.d0
GB(6) = 3.d0
elseif(mass.lt.2.5)then
dx = zpars(6) - (0.975d0*zpars(6) - 0.18d0*2.5d0)
GB(4) = zpars(6) - dx*(mass - 2.d0)/(0.5d0)
GB(5) = 6.d0 - (mass - 2.d0)/(0.5d0)
GB(6) = 3.d0 - (mass - 2.d0)/(0.5d0)
else
GB(4) = MAX(-1.d0,0.5d0*zpars(6) - 0.06d0*mass)
GB(4) = MAX(GB(4),0.975d0*zpars(6) - 0.18d0*mass)
GB(5) = 5.d0
GB(6) = 2.d0
endif
GB(4) = 10.d0**GB(4)
GB(7) = (GB(3)/GB(4))**(1.d0/(GB(5)-GB(6)))
*
* Change in slope of giant L-Mc relation.
lums(6) = GB(4)*GB(7)**GB(5)
*
* HeI ignition luminosity
lums(4) = lHeIf(mass,zpars(2))
lums(7) = lbagbf(mass,zpars(2))
*
if(mass.lt.0.1d0.and.kw.le.1)then
tscls(2) = 1.1d0*tscls(1)
tscls(3) = 0.1d0*tscls(1)
lums(3) = lbgbf(mass)
goto 96
endif
*
if(mass.le.zpars(3))then
* Base of the giant branch luminosity
lums(3) = lbgbf(mass)
* Set GB timescales
tscls(4) = tscls(1) + (1.d0/((GB(5)-1.d0)*GB(1)*GB(4)))*
& ((GB(4)/lums(3))**((GB(5)-1.d0)/GB(5)))
tscls(6) = tscls(4) - (tscls(4) - tscls(1))*((lums(3)/lums(6))
& **((GB(5)-1.d0)/GB(5)))
tscls(5) = tscls(6) + (1.d0/((GB(6)-1.d0)*GB(1)*GB(3)))*
& ((GB(3)/lums(6))**((GB(6)-1.d0)/GB(6)))
* Set Helium ignition time
if(lums(4).le.lums(6))then
tscls(2) = tscls(4) - (1.d0/((GB(5)-1.d0)*GB(1)*GB(4)))*
& ((GB(4)/lums(4))**((GB(5)-1.d0)/GB(5)))
else
tscls(2) = tscls(5) - (1.d0/((GB(6)-1.d0)*GB(1)*GB(3)))*
& ((GB(3)/lums(4))**((GB(6)-1.d0)/GB(6)))
endif
tgb = tscls(2) - tscls(1)
if(mass.le.zpars(2))then
mc1 = mcgbf(lums(4),GB,lums(6))
mc2 = mcagbf(mass)
lums(5) = lzahbf(mass,mc1,zpars(2))
tscls(3) = tHef(mass,mc1,zpars(2))
else
lums(5) = lHef(mass)*lums(4)
tscls(3) = tHef(mass,1.d0,zpars(2))*tscls(1)
endif
else
* Note that for M>zpars(3) there is no GB as the star goes from
* HG -> CHeB -> AGB. So in effect tscls(1) refers to the time of
* Helium ignition and not the BGB.
tscls(2) = tscls(1)
tscls(3) = tHef(mass,1.d0,zpars(2))*tscls(1)
* This now represents the luminosity at the end of CHeB, ie. BAGB
lums(5) = lums(7)
* We set lums(3) to be the luminosity at the end of the HG
lums(3) = lums(4)
endif
*
* Set the core mass at the BGB.
*
if(mass.le.zpars(2))then
GB(9) = mcgbf(lums(3),GB,lums(6))
elseif(mass.le.zpars(3))then
GB(9) = mcheif(mass,zpars(2),zpars(9))
else
GB(9) = mcheif(mass,zpars(2),zpars(10))
endif
*
* FAGB time parameters
*
tbagb = tscls(2) + tscls(3)
tscls(7) = tbagb + (1.d0/((GB(5)-1.d0)*GB(8)*GB(4)))*
& ((GB(4)/lums(7))**((GB(5)-1.d0)/GB(5)))
tscls(9) = tscls(7) - (tscls(7) - tbagb)*((lums(7)/lums(6))
& **((GB(5)-1.d0)/GB(5)))
tscls(8) = tscls(9) + (1.d0/((GB(6)-1.d0)*GB(8)*GB(3)))*
& ((GB(3)/lums(6))**((GB(6)-1.d0)/GB(6)))
*
* Now to find Ltp and ttp using Mc,He,tp
*
mcbagb = mcagbf(mass)
mc1 = mcbagb
if(mc1.ge.0.8d0.and.mc1.lt.2.25d0)then
* The star undergoes dredge-up at Ltp causing a decrease in Mc,He
mc1 = 0.44d0*mc1 + 0.448d0
endif
lums(8) = lmcgbf(mc1,GB)
if(mc1.le.GB(7))then
tscls(13) = tscls(7) - (1.d0/((GB(5)-1.d0)*GB(8)*GB(4)))*
& (mc1**(1.d0-GB(5)))
else
tscls(13) = tscls(8) - (1.d0/((GB(6)-1.d0)*GB(8)*GB(3)))*
& (mc1**(1.d0-GB(6)))
endif
*
* SAGB time parameters
*
if(mc1.le.GB(7))then
tscls(10) = tscls(13) + (1.d0/((GB(5)-1.d0)*GB(2)*GB(4)))*
& ((GB(4)/lums(8))**((GB(5)-1.d0)/GB(5)))
tscls(12) = tscls(10) - (tscls(10) - tscls(13))*
& ((lums(8)/lums(6))**((GB(5)-1.d0)/GB(5)))
tscls(11) = tscls(12) + (1.d0/((GB(6)-1.d0)*GB(2)*GB(3)))*
& ((GB(3)/lums(6))**((GB(6)-1.d0)/GB(6)))
else
tscls(10) = tscls(7)
tscls(12) = tscls(9)
tscls(11) = tscls(13) + (1.d0/((GB(6)-1.d0)*GB(2)*GB(3)))*
& ((GB(3)/lums(8))**((GB(6)-1.d0)/GB(6)))
endif
*
* Get an idea of when Mc,C = Mc,C,max on the AGB
tau = tscls(2) + tscls(3)
mc2 = mcgbtf(tau,GB(8),GB,tscls(7),tscls(8),tscls(9))
mcmax = MAX(MAX(mch,0.773d0*mcbagb - 0.35d0),1.05d0*mc2)
*
if(mcmax.le.mc1)then
if(mcmax.le.GB(7))then
tscls(14) = tscls(7) - (1.d0/((GB(5)-1.d0)*GB(8)*GB(4)))*
& (mcmax**(1.d0-GB(5)))
else
tscls(14) = tscls(8) - (1.d0/((GB(6)-1.d0)*GB(8)*GB(3)))*
& (mcmax**(1.d0-GB(6)))
endif
else
* Star is on SAGB and we need to increase mcmax if any 3rd
* dredge-up has occurred.
lambda = MIN(0.9d0,0.3d0+0.001d0*mass**5)
mcmax = (mcmax - lambda*mc1)/(1.d0 - lambda)
if(mcmax.le.GB(7))then
tscls(14) = tscls(10) - (1.d0/((GB(5)-1.d0)*GB(2)*GB(4)))*
& (mcmax**(1.d0-GB(5)))
else
tscls(14) = tscls(11) - (1.d0/((GB(6)-1.d0)*GB(2)*GB(3)))*
& (mcmax**(1.d0-GB(6)))
endif
endif
tscls(14) = MAX(tbagb,tscls(14))
if(mass.ge.100.d0)then
tn = tscls(2)
goto 100
endif
*
* Calculate the nuclear timescale - the time of exhausting
* nuclear fuel without further mass loss.
* This means we want to find when Mc = Mt which defines Tn and will
* be used in determining the timestep required. Note that after some
* stars reach Mc = Mt there will be a Naked Helium Star lifetime
* which is also a nuclear burning period but is not included in Tn.
*
if(ABS(mt-mcbagb).lt.1.0d-14.and.kw.lt.5)then
tn = tbagb
else
* Note that the only occurence of Mc being double-valued is for stars
* that have a dredge-up. If Mt = Mc where Mc could be the value taken
* from CHeB or from the AGB we need to check the current stellar type.
if(mt.gt.mcbagb.or.(mt.ge.mc1.and.kw.gt.4))then
if(kw.eq.6)then
lambda = MIN(0.9d0,0.3d0+0.001d0*mass**5)
mc1 = (mt - lambda*mc1)/(1.d0 - lambda)
else
mc1 = mt
endif
if(mc1.le.GB(7))then
tn = tscls(10) - (1.d0/((GB(5)-1.d0)*GB(2)*GB(4)))*
& (mc1**(1.d0-GB(5)))
else
tn = tscls(11) - (1.d0/((GB(6)-1.d0)*GB(2)*GB(3)))*
& (mc1**(1.d0-GB(6)))
endif
else
if(mass.gt.zpars(3))then
mc1 = mcheif(mass,zpars(2),zpars(10))
if(mt.le.mc1)then
tn = tscls(2)
else
tn = tscls(2) + tscls(3)*((mt - mc1)/(mcbagb - mc1))
endif
elseif(mass.le.zpars(2))then
mc1 = mcgbf(lums(3),GB,lums(6))
mc2 = mcgbf(lums(4),GB,lums(6))
if(mt.le.mc1)then
tn = tscls(1)
elseif(mt.le.mc2)then
if(mt.le.GB(7))then
tn = tscls(4) - (1.d0/((GB(5)-1.d0)*GB(1)*GB(4)))*
& (mt**(1.d0-GB(5)))
else
tn = tscls(5) - (1.d0/((GB(6)-1.d0)*GB(1)*GB(3)))*
& (mt**(1.d0-GB(6)))
endif
else
tn = tscls(2) + tscls(3)*((mt - mc2)/(mcbagb - mc2))
endif
else
mc1 = mcheif(mass,zpars(2),zpars(9))
mc2 = mcheif(mass,zpars(2),zpars(10))
if(mt.le.mc1)then
tn = tscls(1)
elseif(mt.le.mc2)then
tn = tscls(1) + tgb*((mt - mc1)/(mc2 - mc1))
else
tn = tscls(2) + tscls(3)*((mt - mc2)/(mcbagb - mc2))
endif
endif
endif
endif
tn = MIN(tn,tscls(14))
*
goto 100
*
90 continue
*
* Calculate Helium star Main Sequence lifetime.
*
tm = themsf(mass)
tscls(1) = tm
*
* Zero- and terminal age Helium star main sequence luminosity
*
lums(1) = lzhef(mass)
am = MAX(0.d0,0.85d0-0.08d0*mass)
lums(2) = lums(1)*(1.d0+0.45d0+am)
*
* Set the Helium star GB parameters
*
GB(8) = 8.0d-05
GB(3) = 4.1d+04
GB(4) = 5.5d+04/(1.d0+0.4d0*mass**4)
GB(5) = 5.d0
GB(6) = 3.d0
GB(7) = (GB(3)/GB(4))**(1.d0/(GB(5)-GB(6)))
* Change in slope of giant L-Mc relation.
lums(6) = GB(4)*GB(7)**GB(5)
*
*** Set Helium star GB timescales
*
mc1 = mcgbf(lums(2),GB,lums(6))
tscls(4) = tm + (1.d0/((GB(5)-1.d0)*GB(8)*GB(4)))*
& mc1**(1.d0-GB(5))
tscls(6) = tscls(4) - (tscls(4) - tm)*((GB(7)/mc1)
& **(1.d0-GB(5)))
tscls(5) = tscls(6) + (1.d0/((GB(6)-1.d0)*GB(8)*GB(3)))*
& GB(7)**(1.d0-GB(6))
*
* Get an idea of when Mc = MIN(Mt,Mc,C,max) on the GB
mtc = MIN(mt,1.45d0*mt-0.31d0)
if(mtc.le.0.d0) mtc = mt
mcmax = MIN(mtc,MAX(mch,0.773d0*mass-0.35d0))
if(mcmax.le.GB(7))then
tscls(14) = tscls(4) - (1.d0/((GB(5)-1.d0)*GB(8)*GB(4)))*
& (mcmax**(1.d0-GB(5)))
else
tscls(14) = tscls(5) - (1.d0/((GB(6)-1.d0)*GB(8)*GB(3)))*
& (mcmax**(1.d0-GB(6)))
endif
tscls(14) = MAX(tscls(14),tm)
tn = tscls(14)
*
goto 100
*
95 continue
tm = 1.0d+10
tscls(1) = tm
96 continue
tn = 1.0d+10
*
100 continue
mass = mass0
*
return
end
***