A Search for Late M Supergiant Stars in the Direction of Galactic Latitude −2° < b < 2° and Galactic Longitude 351° < l < 1

Optical late M stars (spectral type later than M4) with IRAS colours of 0.7 < m 12 − m 25 < 1.6 belong to two possible luminosity classes; giants or supergiants (Raharto 1994). We have searched for supergiant candidates among the late M stars at low galactic latitude, between galactic longitude 351° < l < 1° and galactic latitude −2° < b < +2°, using data from the M star Catalogue (Raharto et al. 1984) and the IRAS Point Source Catalogue (Beichman et al. 1987). The search area is located in the direction of the galactic centre. M supergiants found in this survey will be necessarily a mixture of M supergiants in star forming regions in the interarm and galactic centre regions and M supergiants in the inner galactic arms. We found 154 of 1146 late M stars with unique IRAS point source counterparts within 15 arcsec. 122 of the 154 stars have good flux qualities in the 12 and 25 μ m bands. 112 of these, or 73 per cent of the late M stars (later than M4), have IRAS infrared colours in the range 0.7 < m 12 − m 25 < 1.6. Only two stars out of 122 have infrared colours redder than 1.7.