Strong helium 10830-angstrom absorption in Sakurai's object (V4334 Sgr)

We report the appearance and evolution during 1998 of strong neutral helium S-3-P-3(o) absorption at similar to 10830 Angstrom in Sakurai's Object (V4 334 Sgr), which is believed to be a planetary nebula nucleus (PNN) undergoi ng a final helium shell-flash. First detected on 1998 March 18, the profile of the He I feature is P Cygni-like, The absorption depth has increased in three subsequent spectra in 1998, If this is owing to a wind, the profile indicates a wind velocity of similar to 670 +/- 50 km s(-1). The strong CI 10 690-Angstrom line seen prior to the appearance of the helium feature has disappeared; however Sr II and CN absorption features remain present. We t entatively identify several new features as Si I. Taken together with other observations we suggest that the data are consistent with Sakurai's Object entering a phase in which it seems to have become a member of the R Corona e Borealis-type class of stars.