  We describe a search for the A-X infrared bands of AlO with a view to better
understand the characteristics of this radical. These bands are infrequently
encountered in astronomical sources but surprisingly were very prominent in the
spectra of two well-known, nova-like variables (V838 Mon and V4332 Sgr) thereby
motivating us to explore the physical conditions necessary for their
excitation. In this study, we present the detection of A-X bands in the spectra
of 13 out of 17 stars, selected on the basis of their J-K colors as potential
candidates for detection of these bands. The majority of the AlO detections are
in AGB stars viz. 9 OH/IR stars, 2 Mira variables and 2 bright infrared
sources. Our study shows that the A-X bands are fairly prevalent in sources
with low temperature and O-rich environments. Interesting variation in strength
of the AlO bands in one of the sources (IRAS 18530+0817) is reported and the
cause for this is examined. Possible applications of the present study are
discussed in terms of the role of AlO in alumina dust formation, the scope for
estimating the radioactive $^{26}$Al content in AGB stars from the A-X bands,
and providing possible targets for further mm/radio studies of AlO which has
recently been discovered at millimeter wavelengths.

Solar and Stellar Astrophysics