[...]... F., 1994, Atoms in Strong Magnetic Fields , Springer, Berlin Seipp, I., Schweizer, W., 1996, Electric fields for hydrogen bound-free transitions in magnetic white dwarfs, 318:990 Wickramasinghe, D.T., Martin, B., 1986, Magnetic blanketing in white dwarfs, MNRAS 223:323 24 HELIUM DATA FOR STRONG MAGNETIC FIELDS OBTAINED BY FINITE ELEMENT CALCULATIONS Moritz Braun 1 , Wolfgang Schweizer2,3, and Heiko... increasing density using again the equation of state for an ideal gas In the beginning the matter is opti- 2 cally thin, meaning that photons can freely escape and carry away the heat produced by contraction and release of gravitational binding energy The temperature remains approximately constant, and therefore Gravitational forces increase steeper with density and very soon dominate completely over... Max-PlanckInstitut für Astronomie Heidelberg jointly with the Spanish National Commission for Astronomy Atoms and Molecules in Strong External Fields Edited by Schmelcher and Schweizer, Plenum Press, New York, 1998 19 QUANTUM MECHANICAL CALCULATIONS Bound-bound Transitions The non-relativistic single particle Hamiltonian of a hydrogen atom in an external magnetic field B and electric field F (in units... top of definite parity (Braun, 1993) up to a maximum J-value and projecting onto the we obtain the following system of coupled partial differential equations for the functions of the internal coordinates Those functions were determined by expanding them in terms of the adiabatic eigenfunctions, leading to a system of unidimensional differential equations which was finally solved by using the finite element... free-free opacity is not the dominating absorption process in ); his idea that the strange spectrum of can be explained by a strong magnetic field was, however, correct Nevertheless, all attempts to identify the Minkowski bands with various atoms or molecules in magnetic fields of a few MG failed Even for the simplest atoms, hydrogen and helium, accurate calculations for the line components did not exist... ELECTRIC AND MAGNETIC FIELDS AND ITS APPLICATION TO MAGNETIC WHITE DWARFS Susanne Friedrich,1,2* Peter Faßbinder,2 Ingo Seipp,2 Ingo Seipp,2 and Wolfgang Schweizer2* 1 Institut für Astronomie und Astrophysik der Universität Kiel D-24098 Kiel, Germany 2 Institut für Astronomie und Astrophysik der Universität Tübingen D-72076 Tübingen, Germany INTRODUCTION The wavelengths of hydrogen transitions in the strong. .. temperature, and, finally, white dwarfs, where the pressure is supplied by the degenerate electron gas EXTREMELY SIMPLIFIED OVERVIEW OF STELLAR EVOLUTION Let us start from the beginning, the formation of stars, and a little more quantitatively We consider a spherical mass of gas, with radial coordinate r measured from Atoms and Molecules in Strong External Fields Edited by Schmelcher and Schweizer,... Hamiltonian for hydrogen in parallel magnetic and electric fields in atomic units and spherical coordinates reads: with the magnetic field in units of and the electric field strength F in units of In recent years the complex coordinate method has been successfully applied to continuum states The complex rotated Schrödinger equation is then solved numerically by expanding the wavefunctions over a complete basis... (MRR) and of a limiting mass We can understand this qualitatively using the same argumentation as before for the mechanical equilibrium, but now using the equation of state for the degenerate electron gas and the form including the radius instead of density This leads to a relation valid for non-relativistic electrons, that is low-mass white dwarfs The radius decreases with increasing mass and increasing... this contribution we present results obtained for wavelengths of selected dipole transitions in neutral helium at field strengths of up to 1.88 105 Tesla Atoms and Molecules in Strong External Fields Edited by Schmelcher and Schweizer, Plenum Press, New York, 1998 25 THEORY AND METHOD We consider a system consisting of two electrons and a nucleus of charge Ze in a homogeneous magnetic field B along . Chanmugam, G ., 199 0, The physics of white dwarf stars, Rep. Prog. Phys. 53:837 Koester D ., Werner, K. (eds. ), 199 5, White Dwarfs, Lecture Notes in Physics, Vol. 44 3, Springer-Verlag (Heidelberg) Shapiro,. Springer-Verlag (Heidelberg) Shapiro, S.L ., Teukolsky, S.A ., 198 3, Black Holes, White Dwarfs, and Neutron Stars, Wiley & Sons (New York) Vauclair, G ., Schmidt, H ., Koester, D ., Allard, N ., 199 7, White dwarfs observed with. spherical mass of gas, with radial coordinate r measured from Atoms and Molecules in Strong External Fields Edited by Schmelcher and Schweizer, Plenum Press, New York, 1998 1 the center, and m the