Bibcode
Cardona, O.; Crivellari, L.; Simonneau, E.
Bibliographical reference
New Quests in Stellar Astrophysics. II. Ultraviolet Properties of Evolved Stellar Populations, Proceedings of the International Conference held in Puerto Vallarta, Mexico, April 16-20, 2007. Eds.: M. Chavez, E. Bertone, D. Rosa-Gonzalez, and L. H. Rodriguez-Merino, Springer, p. 231-238
Advertised on:
3
2009
Citations
0
Refereed citations
0
Description
A mayor problem that arises in the computation of stellar atmosphere
models is the self consistent determination of the temperature
distribution via the constraint of energy conservation. The energy
balance includes the gains due to the absorption of radiation: int
χ(ν) J(ν) dν, and the losses due to emission: int
χ(ν) S(ν) dν . It is well known that, within each one of
the two above integrals, the part corresponding to spectral ranges whose
opacity χ(ν) is huge can overcome by many orders of magnitude the
part that corresponds to the remaining frequencies. On the other hand,
at those frequencies where χ(ν) is very large, the mean intensity
J(ν) of the radiation field shall be equal, up to many significant
digits, to the source function S(ν) and consequently to the Planck
function B(ν,T). Then their net share to the energy balance shall be
null, albeit separately their contributions to the gain and loss
integrals are the most important numerically. Thus, the spectral range
whose physical contribution to the overall balance is null will dominate
numerically both sides of the energy balance equation, and consequently
the errors on the determination of J(ν) and S(ν) at these
frequencies will falsify the balance. It is possible to circumvent the
numerical problem brought about by the foregoing circumstances by
solving the radiative transfer equation for the variable I(n,ν) -
S(ν), instead of the customary intensity I(n,ν). We present here a
novel iterative algorithm, based on iteration factors already employed
by us with success, which makes it possible a fast correction of the
temperature by computing directly the difference between the radiative
losses and gains at each step of the iterations.