Galactic distributions of carbon-and oxygen-rich AGB stars revealed by the AKARI mid-infrared all-sky survey

D. Ishihara, H. Kaneda, T. Onaka, Y. Ita, M. Matsuura, N. Matsunaga

Research output: Contribution to journalReview articlepeer-review

26 Citations (Scopus)

Abstract

Context. The environmental conditions for asympotic giant branch (AGB) stars to reach the carbon-rich (C-rich) phase are important to understand the evolutionary process of AGB stars. The difference between the spatial distributions of C-rich and oxygen-rich (O-rich) AGB stars is essential for the study of the Galactic structure and the chemical evolution of the interstellar medium. Aims. We quantitatively investigate the spatial distributions of C-rich and O-rich AGB stars in our Galaxy. We discuss the difference between them and its origin. Methods. We classify a large number of AGB stars newly detected by the AKARI mid-infrared all-sky survey. In the color-color diagrams, we define their occupation zones based on the locations of known objects. We then obtain the spatial distributions of C-rich and O-rich AGB stars, assuming that they have the same luminosity for a given mass-loss rate. Results. We find that O-rich AGB stars are concentrated toward the Galactic center and that the density decreases with Galactocentric distance, whereas C-rich AGB stars show a relatively uniform distribution within about 8 kpc of Sun. Conclusions. Our result confirms the trends reported in previous studies and extends them to a Galactic scale. We discuss the relations between our result, the Galactic metallicity gradient, and the chemical evolution of the ISM in our Galaxy.

Original languageEnglish
Article numberA79
JournalAstronomy and Astrophysics
Volume534
DOIs
Publication statusPublished - 2011

Keywords

  • AGB and post-AGB
  • Galaxy
  • ISM
  • infrared
  • mass-loss
  • stars
  • structure

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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