Document Type

Article

Publication Date

8-1-2010

Publication Title

The Astronomical Journal

Volume

140

Issue

2

Publisher

The American Astronomical Society

Abstract

The concept of kinematic assemblages evolving from dispersed stellar clusters has remained contentious since Eggen’s initial formulation of moving groups in the 1960s. With high-quality parallaxes from the Hipparcos space astrometry mission, distance measurements for thousands of nearby, seemingly isolated stars are currently available. With these distances, a high-resolution spectroscopic abundance analysis can be brought to bear on the alleged members of these moving groups. If a structure is a relic of an open cluster, the members can be expected to be monolithic in age and abundance in as much as homogeneity is observed in young open clusters. In this work, we have examined 34 putative members of the proposed Wolf 630 moving group using high-resolution stellar spectroscopy. The stars of the sample have been chemically tagged to determine abundance homogeneity and confirm the existence of a homogeneous subsample of 19 stars. Fitting the homogeneous subsample with Yale–Yonsei isochrones yields a single evolutionary sequence of ∼2.7 ± 0.5 Gyr. It is concluded that this 19 star subsample of the Wolf 630 moving group sample of 34 stars could represent a dispersed cluster with an [Fe/H]=−0.01 ± 0.02 and an age of 2.7 ± 0.5 Gyr. In addition, chemical abundances of Na and Al in giants are examined for indications of enhancements as observed in field giants of old open clusters; overexcitation/ionization effects are explored in the cooler dwarfs of the sample; and oxygen is derived from the infrared triplet and the forbidden line at λ6300.

Comments

This manuscript has been published in the Astrophysical Journal. Please find the published version here (note that a subscription is necessary to access this version):

http://iopscience.iop.org/1538-3881/140/2/293/article?fromSearchPage=true

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