  For decades ever since the early detection in the 1990s of the emission
spectral features of crystalline silicates in oxygen-rich evolved stars, there
is a long-standing debate on whether the crystallinity of the silicate dust
correlates with the stellar mass loss rate. To investigate the relation between
the silicate crystallinities and the mass loss rates of evolved stars, we carry
out a detailed analysis of 28 nearby oxygen-rich stars. We derive the mass loss
rates of these sources by modeling their spectral energy distributions from the
optical to the far infrared. Unlike previous studies in which the silicate
crystallinity was often measured in terms of the crystalline-to-amorphous
silicate mass ratio, we characterize the silicate crystallinities of these
sources with the flux ratios of the emission features of crystalline silicates
to that of amorphous silicates. This does not require the knowledge of the
silicate dust temperatures which are the major source of uncertainties in
estimating the crystalline-to-amorphous silicate mass ratio. With a Pearson
correlation coefficient of ~0.24, we find that the silicate crystallinities and
the mass loss rates of these sources are not correlated. This supports the
earlier findings that the dust shells of low mass-loss rate stars can contain a
significant fraction of crystalline silicates without showing the
characteristic features in their emission spectra.
