We have identified 484 lines of the trans-iron elements (TIEs) Zn, Ga, Ge, Se, Br, Kr, Sr, Zr, Mo, In, Te, I, Xe, and Ba, for the first time in the ultraviolet spectrum of a DAO-type WD, namely BD−22∘3467, surrounded by the ionized nebula Abell 35. Our TIE abundance determination shows extremely high overabundances of up to five dex -- a similar effect is already known from hot, H-deficient (DO-type) white dwarfs. In contrast to these where a pulse-driven convection zone has enriched the photosphere with TIEs during a final thermal pulse and radiative levitation has established the extreme TIE overabundances, {here the extreme TIE overabundances are exclusively driven by radiative levitation on the initial stellar metallicity. The very low mass (0.533−0.025+0.040M⊙) of BD−22∘3467 implies that a third dredge-up with enrichment of s-process elements in the photosphere did not occur in the AGB precursor.
@article{arxiv.1911.09573,
title = {First discovery of trans-iron elements in a DAO-type white dwarf (BD$-22{^\circ}3467$)},
author = {L. Löbling and M. A. Maney and T. Rauch and P. Quinet and S. Gamrath and J. W. Kruk and K. Werner},
journal= {arXiv preprint arXiv:1911.09573},
year = {2020}
}