SBS 1150+599A: An extremely oxygen-poor planetary nebula in the Galactic halo?
OAN, Instituto de Astronomía, UNAM, México
2 DAEC, Observatoire de Meudon, 92195 Meudon Cedex, France e-mail: email@example.com
3 Instituto Nacional de Astrofísica Optica y Electrónica, AP 51 y 216, Puebla, Pue., México e-mail: firstname.lastname@example.org
4 Instituto de Astrofísica de Canarias, Ave. Via Láctea s/n, 38200 La Laguna, Tenerife, Spain e-mail: email@example.com
Corresponding author: G. Tovmassian, firstname.lastname@example.org
Accepted: 7 February 2001
We report results of a spectrophotometric study of SBS 1150+599A and discuss the nature of this object based upon our data. Our study shows that SBS 1150+599A is most probably a planetary nebula located in the Galactic halo and not a cataclysmic variable as originally proposed by the authors of the Second Byurakan Survey from low resolution spectroscopy. We have further elaborated on the properties of SBS 1150+599A (now becoming PN G135.9+55.9) with tools used for planetary nebula analysis. Our photoionization models show that, in order to match the observational constraints, the oxygen abundance in the nebula is probably extremely low, around 1/500 solar, which is one order of magnitude lower than the most oxygen-poor planetary nebulae known so far. This finding has strong implications on our understanding of the formation of planetary nebulae and of the evolution of the Galactic halo.
Key words: ISM: planetary nebulae: general / ISM: planetary nebulae: individual: SBS 1150+599A (PN G135.9+55.9), / galaxies: halos / stars: binaries: symbiotic / stars: cataclysmic variables
© ESO, 2001