Sorry, your browser does not support JavaScript!

Evolutionary models and diffusion timescales


Fill in the fields to get the corresponding white dwarf properties and diffusion timescales.

White dwarf spectral type:

Envelope thickness:


Download output as plain text file:

White dwarf properties*

Mass Radius Luminosity Cooling time Gravitational redshift Envelope mass ratio log(q)
M R L Gyr km/s

Log of diffusion timescale (in years)**

H
He
Li
Be
B
C
N
O
F
Ne
Na
Mg
Al
Si
P
S
Cl
Ar
K
Ca
Sc
Ti
V
Cr
Mn
Fe
Co
Ni
Cu
Zn
Ga
Ge
As
Se
Br
Kr




Notes

* Fontaine et al. 2001, The Potential of White Dwarf Cosmochronology. ADS

** Some 25 years after Paquette et al. (1986, ApJS, 61, 177), we recently improved significantly on their calculations of diffusion coefficients by 1) using a much more accurate numerical scheme for estimating the so-called collision integrals, and 2) introducing a more physical prescription of the screening length used as the independent variable in the evaluation of these coefficients. Details of these improved calculations will be provided elsewhere. Likewise, at the level of the white dwarf models themselves, we 1) introduced an improved model of pressure ionization to insure that the average charge of an heavy element is best evaluated and changes smoothly with depth, and 2) computed new settling timescales for all 27 elements from Li to Cu in the periodic table. -Gilles Fontaine












The Montreal White Dwarf Database is produced and maintained by Prof. Patrick Dufour at Université de Montréal. Please send database updates, corrections, suggestions or bug reports to dufourpa@astro.umontreal.ca.