An infrared study of galactic OH/IR stars

II. The “GLMP sample” of red oxygen-rich AGB stars

¹ ISO Data Centre / European Space Astronomy Center, Villafranca del Castillo, Apartado de Correos 50727, 28080 Madrid, Spain e-mail: fjimenez@iso.vilspa.esa.es
² Hamburger Sternwarte, Gojenbergsweg 112, 21029 Hamburg, Germany e-mail: Francisco.Jimenez-Esteban@hs.uni-hamburg.de
³ ISO Data Centre / European Space Astronomy Center, Research and Scientific Support Department of ESA, Villafranca del Castillo, Apartado de Correos 50727, 28080 Madrid, Spain

Received: 19 April 2005
Accepted: 21 July 2005

Abstract

We present optical and near-infrared finding charts taken from the DSS and 2MASS surveys of 94 IRAS sources selected from the GLMP catalogue, and accurate astrometry (≈0.2´´) for most of them. Selection criteria were very red IRAS colours representative for OH/IR stars with optically thick circumstellar shells and the presence of variability according to the IRAS variability index (). The main photometric properties of the stars in this “GLMP sample” are presented, discussed and compared with the correspondent properties of the “Arecibo sample” of OH/IR stars studied nearlier. We find that 37% of the sample () has no counterpart in the 2MASS, implying extremely high optical depths of their shells. Most of the sources identified in the 2MASS are faint () and are of very red colour in the near-infrared, as expected. The brightest 2MASS counterpart ( mag) was found for IRAS 18299–1705. Its blue colour suggests that IRAS 18299–1705 is a post-AGB star. Few GLMP sources have faint but relatively blue counterparts. They might be misidentifed field stars or stars that recently experienced a drop of their mass loss rates. The “GLMP sample” in general is made of oxygen-rich AGB stars, which are highly obscured by their circumstellar shells. They belong to the same population as the reddest OH/IR stars in the “Arecibo sample”.