7 Conclusions

We have explored recent techniques for computing Balmer line profiles in the sun, and H$\alpha$ profiles in several models with effective temperatures ranging from 4500 K to 12 000 K. We find that new Stark profiles, rigorous convolution, and improved interpolation techniques make almost no difference in the resulting calculated profiles, compared with algorithms used in the Kurucz codes for several decades.

Good fits to normalized disk center solar profiles for the H$\alpha$ through H$\delta$ are obtained from the Holweger-Müller (HM) model, provided that some adjustment of the computed continuum is performed according to the hypothesis of missing opacity.

The H$\alpha$ profile can also be reasonably fitted in absolute intensity, but the calculated continua for H$\beta$ through H$\delta$ are too high. This may reasonably be attributed to missing UV opacity, perhaps also to inadequacies of the HM model used here, as well as to uncertainties in the absolute solar calibration.

In spite of severe temperature inhomogeneities in the solar atmosphere, the plane-parallel model appears remarkably robust.

Acknowledgements

Numerous scientific colleagues have kindly consulted with us on various parts of this project, and we will doubtless omit some unintentionally. For this we apologize. Explicit thanks are due to Drs. P. Barklem, N. Grevesse, K. Fuhrmann, R. L. Kurucz, M. Lemke, H. Neckel, J. Sauval, B. Smalley, and C. Stehlé.