A spectroscopic atlas of post-AGB stars and planetary nebulae selected from the IRAS point source catalogue
Laboratorio de Astrofísica Espacial y Física Fundamental, INTA, Apartado de Correos 50727, 28080 Madrid, Spain e-mail: email@example.com
2 Research and Scientific Support Department of ESA, European Space Astronomy Centre, Villafranca del Castillo, Apartado de Correos 50727, 28080 Madrid, Spain
3 Instituto de Astrofísica de Canarias, c/via Lactea, s/n, 38200 La Laguna, Tenerife, Spain
4 Consejo Superior de Investigaciones Científicas (CSIC), Spain
5 Departamento de Ciencias de la Navegación y de la Tierra, E.T.S. de Náutica y Máquinas, Universidade da Coruña, 15011 A Coruña, Spain
6 Departamento de Física Aplicada, Facultade de Ciencias do Mar, Campus Marcosende-Lagoas, Universidade de Vigo, 36310 Vigo, Pontevedra, Spain
7 Kapteyn Astronomical Institute, Postbus 800, 9700 AV Groningen, The Netherlands
Accepted: 5 July 2006
Aims.We study the optical spectral properties of a sample of stars showing far infrared colours similar to those of well-known planetary nebulae. The large majority of them were unidentified sources or poorly known in the literature at the time when this spectroscopic survey started, some 15 years ago.
Methods.We present low-resolution optical spectroscopy, finding charts and improved astrometric coordinates of a sample of 253 IRAS sources.
Results.We have identified 103 sources as post-AGB stars, 21 as “transition sources”, and 36 as planetary nebulae, some of them strongly reddened. Among the rest of sources in the sample, we were also able to identify 38 young stellar objects, 5 peculiar stars, and 2 Seyfert galaxies. Up to 49 sources in our spectroscopic sample do not show any optical counterpart, and most of them are suggested to be heavily obscured post-AGB stars, rapidly evolving on their way to becoming planetary nebulae.
Conclusions.An analysis of the galactic distribution of the sources identified as evolved stars in the sample is presented together with a study of the distribution of these stars in the IRAS two-colour diagram. Finally, the spectral type distribution and other properties of the sources identified as post-AGB in this spectroscopic survey are discussed in the framework of stellar evolution.
Key words: planetary nebulae: general / stars: AGB and post-AGB / stars: mass-loss / atlases
© ESO, 2006