Chemical evolution of the orion association. I. The oxygen abundance of main-sequence B stars

Katia Cunha, David L. Lambert

Research output: Contribution to journalArticlepeer-review

78 Scopus citations


Oxygen abundances are presented from LTE and non-LTE analyses of O II lines in spectra of 18 B main-sequence stars of the four subgroups comprising the Orion association. The lowest abundances are found in the oldest subgroups (Ia and Ib). The youngest subgroup Id, the Trapezium cluster, and some stars of the slightly older Ic subgroup seem to have an abundance that is up to about 40% higher. It is suggested that this enrichment resulted from the mixing of supernovae ejecta from the Ic subgroup with those adjacent portions of the dense molecular cloud that subsequently collapsed to form the Trapezium cluster. These stellar analyses confirm published abundance analyses of the H II region's emission lines that show Orion to have an oxygen abundance that is less than that of the Sun: the mean LTE/NLTE abundances are log ∈(O) = 8.67/8.65 ± 0.12 for the 18 stars whereas the solar abundance is log ∈(O) = 8.93.

Original languageEnglish (US)
Pages (from-to)586-598
Number of pages13
JournalAstrophysical Journal
Issue number2
StatePublished - 1992
Externally publishedYes


  • Open clusters and associations: Individual (orion)
  • Stars: Abundances

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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