The Stark line profiles are calculated using the Model Microfield Method of Brissaud and Frisch (J. Quant. Spectrosc. Rad. Transfer 11, 1767 (1971) ) which includes the effects of the motions of the plasmas ions. Such effects are important in the line centers.
The online calculation is performed for a plasma composed of electrons and protons.

The details of the model and the numerical methods are given in [2,3]:
In this preliminary online version, the tabulations are given in alfa units (Angstroms/ues) , which are defined by Delta_alfa = Delta_lambda (Angstroms) / F0 , where F0 is the the normal Holtsmark field F0 defined by F0 = e/R0^2 = 1.25 10-9 Ne^(2/3) ( ues, cm-3) ( see ref 2) .
The area normalized profile includes the contributions of electrons and protons. The line shape recovers in the far line wings the well known static limit in I(Delta_alfa) = Kalpha/| Delta_alfa |^2.5 . The calculation gives the pure Stark broadened profile and also the convolution with the Doppler profile. Only the half profile (positive values of Delta_alfa) is given.
This online calculation can be used alternatively to the existing tabulations at CDS (http://cdsweb.u-strasbg.fr/cgi-bin/qcat?VI/98) with appropriate interpolation in the tables.

We encourage the users to cite references 2 and 3 for publication purposes.

Two calculations will be proposed (beta test) :

• a detailed (more precise) calculation which takes into account the tensorial form of the electron contribution to the line shape. It is proposed for Lyman (1 – n’, with n’ =2,3,4,5,6) and Balmer lines ( 2=n’, with n’=3,4,5)
• a simplified calculation (soon available), for the other Balmer and Paschen lines. It supposes that the electron contribution has a scalar form and allows a faster computation. The accuracy is discussed in [2,3].

Note that the Debye approximation is supposed to be valid. This means that the input temperature T(K) and electron density Ne (cm-3) should satisfy the relation 0.9 Ne^0.1666/T^0.5 < 1

References :

• [1] Theory of Stark broadening , Exact line profile with model microfield., Brissaud and Frisch , J. Quant. Spectrosc. Rad. Transfer 11, 1767 (1971)
• [2] Extensive MMM tabulations of Hydrogen Lyman and Balmer lines, Stehle C., Hutcheon R., Astron, Astrophys. Suppl. 140, 93 (1999)
• [3] Paschen Lines of Hydrogen and He+ ion, Stehle C., Physica Scripta, T65, 183-187, (1996).

Contacts :
Chantal Stehle , Sylvain Fouquet

An exact expression for the dipole radial integral of hydrogen has been given by Gordon [Ann. Phys. 2 (1929) 1031]. It contains two hypergeometric functions F(a,b;c;x), which are difficult to calculate directly, when the (negative) integers a, are large, as in the case of high Rydberg states of hydrogenic ions. We have derived a simple method [D. Hoang-Binh, Astron.Astrophys. 238 (1990) 449], using a recurrence relation to calculate exactly F, starting from two initial values, which are very easy to compute. We present here a numerical code using this method, to compute exact hydrogenic oscillator strengths, Einstein coefficients, and lifetimes.
Contacts :
Dy HOANG BINH