  Double lined spectroscopic binaries in an evolved stage of evolution are
expected to be extremely rare since they must consist of equally luminous and
thus almost equally evolved objects, which requires an extremely similar
initial mass. In this contribution we discuss such rare double evolved SB2
system: HD172481. This binary includes an F-type post-AGB object and an M-type
AGB companion. The spectrum shows a surprisingly strong LiI 670.8nm line with
an equivalent width of 54mA yielding a lithium abundance of log(Li)=3.6.
Several explanations for this huge lithium content are explored.

Astrophysics