A kine-chemical investigation of the AB Dor moving group "stream"

Scott A. Barenfeld, Eric J. Bubar, Eric E. Mamajek, Patrick Young

Research output: Contribution to journalArticle

62 Scopus citations

Abstract

The AB Dor Moving Group consists of a "nucleus" of ∼10 stars at d ≃ 20 pc, along with dozens of purported "stream" members distributed across the sky. We perform a chemical and kinematic analysis of a subsample of AB Dor stream stars to test whether they constitute a physical stellar group. We use the NEMO Galactic kinematic code to investigate the orbits of the stream members, and perform a chemical abundance analysis using high resolution spectra taken with the Magellan Clay 6.5 m telescope. Using a χ2 test with the measured abundances for 10 different elements, we find that only half of the purported AB Dor stream members could possibly constitute a statistically chemically homogeneous sample. Some stream members with three-dimensional velocities were hundreds of parsecs from the AB Dor nucleus ∼108 yr ago, and hence were unlikely to share a common origin. We conclude that the published lists of AB Dor moving group stream members are unlikely to represent the dispersed remnant of a single star formation episode. A subsample of the stream stars appears to be both statistically chemically homogeneous and in the vicinity of the AB Dor nucleus at birth. Their mean metallicity is [Fe/H] = 0.02 ± 0.02 dex, which we consider representative for the AB Dor group. Finally, we report a strong lower limit on the age of the AB Dor nucleus of >110 Myr based on the pre-main sequence contraction times for K-type members which have reached the main sequence.

Original languageEnglish (US)
Article number6
JournalAstrophysical Journal
Volume766
Issue number1
DOIs
StatePublished - Mar 20 2013

Keywords

  • open clusters and associations: individual (AB Dor Moving Group)
  • stars: abundances
  • stars: kinematics and dynamics
  • stars: late-type

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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