  IRAS 15099-5856 in the young supernova remnant (SNR) MSH 15-52 is the first
and only SNR-associated object with crystalline silicate dust detected so far,
although its nature and the origin of the crystalline silicate are still
unclear. In this paper, we present high-resolution mid-infrared (MIR) imaging
observations of the bright central compact source IRS1 of IRAS 15099-5856 to
study the spatial distributions of gas and dust and the analysis of its Spitzer
MIR spectrum to explore the origin of IRS1. The MIR images obtained with the
T-ReCS attached on the Gemini South telescope show a complicated, inhomogeneous
morphology of IRS1 with bright clumps and diffuse emission in [Ne II] 12.81
$\mu$m and Qa 18.30 $\mu$m, which confirms that IRS1 is an extended source
externally heated by the nearby O star Muzzio 10, a candidate for the binary
companion of the progenitor star. The Spitzer MIR spectrum reveals several
ionic emission lines including a strong [Ne II] 12.81 $\mu$m line, but no
hydrogen line is detected. We model the spectrum using the photoionization code
CLOUDY with varying elemental composition. The elemental abundance of IRS1
derived from the model is close to that of SN ejecta with depleted hydrogen and
enhanced metals, particularly neon, argon, and iron. Our results imply that
IRS1 originates from the SN ejecta and suggest the possibility of the formation
of crystalline silicate in newly-formed SN dust.
