  We present the Spitzer/Infrared Spectrograph spectrum of the main-sequence
star HD165014, which is a warm (>~ 200 K) debris disk candidate discovered by
the AKARI All-Sky Survey. The star possesses extremely large excess emission at
wavelengths longer than 5 \mum. The detected flux densities at 10 and 20 \mum
are ~ 10 and ~ 30 times larger than the predicted photospheric emission,
respectively. The excess emission is attributable to the presence of
circumstellar warm dust. The dust temperature is estimated as 300-750 K,
corresponding to the distance of 0.7-4.4 AU from the central star. Significant
fine-structured features are seen in the spectrum and the peak positions are in
good agreement with those of crystalline enstatite. Features of crystalline
forsterite are not significantly seen. HD165014 is the first debris disk sample
that has enstatite as a dominant form of crystalline silicate rather than
forsterite. Possible formation of enstatite dust from differentiated parent
bodies is suggested according to the solar system analog. The detection of an
enstatite-rich debris disk in the current study suggests the presence of large
bodies and a variety of silicate dust processing in warm debris disks.
