MIDINFRARED SPECTRAL OBSERVATIONS OF POINT SOURCES BY IRTS

The mid-infrared spectrometer on board Infrared Telescope in Space has detected thousands of pointlike sources in the spectral range of 4.5- 11.7 mu m. Extraction of point sources from the survey data has been c arried out for the observing period after the spin-flip, where accurat e pointing information is presently available, and 129 point sources h ave been extracted with signal-to-noise ratios greater than 3 througho ut the MIRS spectral range. A two-color diagram of these objects, deri ved from bands of 5 mu m, 8 mu m, and 10 mu m of the sources, is prese nted. The sources can be classified into five groups on the diagram: v isible late-type stars, stars with dust envelopes, stars with silicate emission, objects with the unidentified infrared (UIR) emission bands , and very peculiar red objects. With the help of the 5 mu m and 8 Irm colors, objects with the UIR bands can clearly be distinguished from objects without those features. The characteristics of the sources in each group are discussed based on the spectra.