2018ApJ...860...49M -
Astrophys. J., 860, 49-49 (2018/June-2)
Optical high-resolution spectroscopy of 14 young α-rich stars.
MATSUNO T., YONG D., AOKI W. and ISHIGAKI M.N.
Abstract (from CDS):
We report chemical abundances of 14 young α-rich stars including neutron-capture elements based on high-quality optical spectra from HIRES/Keck I and differential line-by-line analysis. From a comparison of the abundance patterns of young α-rich stars to those of nearby bright red giants with a similar metallicity range (-0.7 < [Fe/H] < -0.2), we confirm their high α-element abundances reported by previous studies based on near-infrared spectroscopy. We reveal for the first time low abundances of s-process elements and high abundances of r-process elements. All the abundances are consistent with those seen in the typical α-rich population of the Galactic disk, and no abundance anomalies are found except for Li-enhancement in one object previously reported and mild enhancement of Na in two stars. In particular, the lack of s-process enhancement excludes the hypothesis that mass transfer from asymptotic giant branch stars plays an important role in the formation of young α-rich stars. The high frequency of radial velocity variation (more than 50%) is also confirmed. We argue that mass transfer from low-mass red giants is the likely dominant formation mechanism for young α-rich stars.
Abstract Copyright:
© 2018. The American Astronomical Society. All rights reserved.
Journal keyword(s):
stars: abundances
VizieR on-line data:
<Available at CDS (J/ApJ/860/49): table1.dat table2.dat table3.dat table4.dat>
Simbad objects:
32
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