J/A+A/555/A96 White dwarf cooling timescales (Salaris+, 2013)
Comparison of theoretical white dwarf cooling timescales. (Research Note).
Salaris M., Althaus L.G., Garcia-Berro E.
<Astron. Astrophys. 555, A96 (2013)>
=2013A&A...555A..96S 2013A&A...555A..96S
ADC_Keywords: Models ; Stars, white dwarf
Keywords: stars: interiors - stars: evolution - white dwarfs
Abstract:
An accurate assessment of white dwarf cooling times is paramount so
that white dwarf cosmochronology of Galactic populations can be put on
more solid grounds. This issue is particularly relevant in view of the
enhanced observational capabilities provided by the next generation of
extremely large telescopes, that will offer more avenues to use white
dwarfs as probes of Galactic evolution and test-beds of fundamental
physics.
We estimate for the first time the consistency of results obtained
from independent evolutionary codes for white dwarf models with fixed
mass and chemical stratification, when the same input physics is
employed in the calculations.
We compute and compare cooling times obtained from two independent and
widely used stellar evolution codes, BaSTI and LPCODE evolutionary
codes, using exactly the same input physics for 0.55M☉ white
dwarf models with both pure carbon and uniform carbon-oxygen (50/50
mass fractions) cores , and pure hydrogen layers with mass fraction
qH=10-4MWD on top of pure helium buffers of mass qHe=10-2MWD.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 64 511 *Results of BaSTI calculation
table2.dat 64 509 *Results of BaSTI calculation for step 1
table3.dat 64 521 *Results of BaSTI calculation for step 2 (with
opacities by Cassisi et al. 2007ApJ...661.1094C 2007ApJ...661.1094C)
table4.dat 64 760 *Results of BaSTI calculation for step 3 (with
boundaries by Rohrmann et al. 2012A&A...546A.119R 2012A&A...546A.119R)
EOS_mm.f 72 292 Equation of State routine
thermo.tab 80 5359 Table associated to EOS_mm.f
Phasediagram.f 68 65 Phasediagram routine
Boundcon.f 76 161 Boundcon routine
M.dat 347 76 Table associated to Boundcon.f
P.dat 347 76 Table associated to Boundcon.f
R.dat 347 76 Table associated to Boundcon.f
T.dat 347 76 Table associated to Boundcon.f
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Note on table1.dat, table2.dat, table3.dat, table4.dat:
computation with the BaSTI evolutionary code for a white dwarf of
M=055M☉ with pure carbon and uniform carbon-oxygen (50/50 mass
fractions) cores, and pure hydrogen layers with mass fraction
qH=10-4MWD on top of pure helium buffers of mass qHe=10-2MWD.
All steps use the Equation Of State (EOS) from Magni & Mazzitelli
(1979A&A....72..134M 1979A&A....72..134M)
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Description of file:
≡ Routine Phasediagram.f
I =mesh
c OX_I =input O abundance (mass fraction
c OX_FINAL =output O abundance (mass fraction)
≡ Routine EOS_mm.f
The routine needs to be called for the first time just to read the
tables 'thermo.tab'.
From the second call on, GAS PRESSURE
(NOT TOTAL PRESSURE) in cgs, and temperature
(TE) in K must be entered (variables PR and TE),
to get, as an output: density (RHO),
adiabatic gradient (GRAD), Cp at constant pressure (CSPE) and
molecular weight (PMOL).
In COMMON /01/ one needs to enter the
abundances (in mass fraction) of: Hydrogen; He_3; He_4; C_12,
C_13, N_14, N_15, 0_16 and O_17
≡ Routine Boundcon.f in boundary_conditions.tar
Reads tables M.dat, P.dat, R.dat, T.dat
Input data are the effective temperature in 10^6K (Teff) and the surface
gravity (gsup).
Pressure, temperature, outer linear radius,
and outer mass fraction at an optical depth of τ_ross%.1188
are calculated (pre_atm, temp_atm, rad_atm, dmass_atm).
Byte-by-byte Description of file(#): table1.dat table2.dat table3.dat table4.dat
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Bytes Format Units Label Explanations
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3- 15 F13.10 [yr] log.t logarithm base 10 age
17- 23 F7.4 [Lsun] logL logarithm base 10 bolometric luminosity units
26- 32 F7.5 [K] logTe logarithm base 10 effective temperature
34- 40 F7.5 Rsun R Surface radius
42- 48 F7.4 dPa logPc logarithm base 10 central pressure
(in cgs units =dyn.cm-2 =0.1Pa)
51- 56 F6.4 [K] logTc logarithm base 10 central temperature
59- 64 F6.4 [g/cm3] logRhoc logarithm base 10 central density
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Acknowledgements:
Maurizio Salaris, M.Salaris(at)ljmu.ac.uk
(End) Patricia Vannier [CDS] 01-Jul-2013