31 Aquilae is the only evolved star for which SMR status was confirmed
by Taylor (1991). For this reason, a new determination of the atmosph
eric parameters and chemical composition of 31 Aql has been made. The
observational material consists of high-dispersion coude echelle spect
ra obtained with a CCD detector and the l-m telescope of the Special O
bservatory of the Russian Academy of Sciences. The new value of [Fe/H]
obtained here is +0.32+/-0.15 dex. This is close to the upper limit o
f [Fe/H] for dwarf stars belonging to the thin disk of the Galaxy. The
value of the Li abundance log A(Li) = 1.35. The value [C/H] obtained
here is -0.05 +/- 0.11 dex. Within the errors, solar values of [elemen
t/Fe] are obtained for Na, Y, Zr, Pa, La, Ce, Pr, and Nd. The age of 3
1 Aql and its location in the Galaxy are estimated, and a careful anal
ysis of abundance determination errors is carried out. 31 Aql is found
to be in the evolutionary stage in which the convective envelope begi
ns to extend.