A KINE-CHEMICAL INVESTIGATION OF THE AB DOR MOVING GROUP “STREAM”

The AB Dor Moving Group consists of a "nucleus" of ~10 stars at d [Asymptotically = to] 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 const...

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Published inThe Astrophysical journal Vol. 766; no. 1; pp. 1 - 7
Main Authors BARENFELD, SCOTT A, Bubar, Eric J, MAMAJEK, ERIC E, Young, Patrick A
Format Journal Article
LanguageEnglish
Published United States 20.03.2013
Subjects
ABUNDANCE
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
Asymptotic properties
CHEMICAL ANALYSIS
CONTRACTION
COSMIC NUCLEI
Kinematics
Nuclei
ORBITS
RESOLUTION
Samples
SKY
SPECTRA
STARS
Statistical methods
STELLAR FLARES
Streams
TELESCOPES
Three dimensional
THREE-DIMENSIONAL CALCULATIONS
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Summary:The AB Dor Moving Group consists of a "nucleus" of ~10 stars at d [Asymptotically = to] 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 chi super(3) 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 ~10 super(8) 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 + or -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.
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ISSN:0004-637X
1538-4357
DOI:10.1088/0004-637X/766/1/6