  The UV-bright star Barnard 29 in the globular cluster M13 was observed for
5300 seconds with the Berkeley spectrometer on the ORFEUS-SPAS II Mission in
1996 November-December. The resulting spectrum extends from the interstellar
cutoff at 912 A to ~ 1200 A at a resolution of ~ 0.33 A. It shows numerous
absorption features, both photospheric and interstellar, but no significant
emission other than diffuse emission of local origin. The Kurucz synthetic
stellar spectrum that best fits the data has T_eff = 21,000 K, log g = 3.0, and
[M/H] = -2.5. This effective temperature and surface gravity are consistent
with previous results, but the derived metallicity is lower than that of other
M13 giants, for which [Fe/H] = -1.60. Using high-resolution synthetic spectra,
we determine the photospheric abundances of C, S, and Fe, species unobservable
in the optical. We find log epsilon(C) = 6.15 +/- 0.10, log epsilon(S) = 5.34
+/- 0.50, and log epsilon(Fe) = 5.30 (+0.22, -0.26). Again, the Fe abundance is
lower than expected. This anomaly may reflect selective condensation of metals
onto dust grains at the end of the AGB phase, as has been suggested for some
cooler post-AGB stars with peculiar Fe abundances.
