Metal-poor stars observed with the automated planet finder telescope. I. Discovery of five carbon-enhanced metal-poor stars from LAMOST. (arXiv:1904.09603v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Mardini_M/0/1/0/all/0/1">Mohammad K. Mardini</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Li_H/0/1/0/all/0/1">Haining Li</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Placco_V/0/1/0/all/0/1">Vinicius M. Placco</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Alexeeva_S/0/1/0/all/0/1">Sofya Alexeeva</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Carollo_D/0/1/0/all/0/1">Daniela Carollo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Taani_A/0/1/0/all/0/1">Ali Taani</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ablimit_I/0/1/0/all/0/1">Iminhaji Ablimit</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wang_L/0/1/0/all/0/1">Liang Wang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zhao_G/0/1/0/all/0/1">Gang Zhao</a>
We report on the discovery of five carbon-enhanced metal-poor (CEMP) stars in
the metallicity range of $-3.3<$ [Fe/H] $<-2.4$. These stars were selected from
the LAMOST DR3 low-resolution (R$ sim$ 2,000) spectroscopic database as
metal-poor candidates and followed-up with high-resolution spectroscopy (R$
sim$110,000) with the LICK/APF. Stellar parameters and individual abundances
for 25 chemical elements (from Li to Eu) are presented for the first time.
These stars exhibit chemical abundance patterns that are similar to those
reported in other literature studies of very and extremely metal-poor stars.
One of our targets, J2114$-$0616, shows high enhancement in carbon
([C/Fe]=1.37), nitrogen ([N/Fe]= 1.88), barium ([Ba/Fe]=1.00), and europium
([Eu/Fe]=0.84). Such chemical abundance pattern suggests that J2114$-$0616 can
be classified as CEMP-r/s star. In addition, the star J1054+0528 can be
classified as a CEMP-rI star, with [Eu/Fe]=0.44 and [Ba/Fe]=$-$0.52. The other
stars in our sample show no enhancements in neutron-capture elements and can be
classified as CEMP-no stars. We also performed a kinematic and dynamical
analysis of the sample stars based on Gaia DR2 data. The kinematic parameters,
orbits, and binding energy of these stars, show that J2114$-$0616 is member of
the outer halo population, while the remaining stars belong to the inner halo
population but with an accreted origin. Collectively, these results add
important constraints on the origin and evolution of CEMP stars as well as on
their possible formation scenarios.
We report on the discovery of five carbon-enhanced metal-poor (CEMP) stars in
the metallicity range of $-3.3<$ [Fe/H] $<-2.4$. These stars were selected from
the LAMOST DR3 low-resolution (R$ sim$ 2,000) spectroscopic database as
metal-poor candidates and followed-up with high-resolution spectroscopy (R$
sim$110,000) with the LICK/APF. Stellar parameters and individual abundances
for 25 chemical elements (from Li to Eu) are presented for the first time.
These stars exhibit chemical abundance patterns that are similar to those
reported in other literature studies of very and extremely metal-poor stars.
One of our targets, J2114$-$0616, shows high enhancement in carbon
([C/Fe]=1.37), nitrogen ([N/Fe]= 1.88), barium ([Ba/Fe]=1.00), and europium
([Eu/Fe]=0.84). Such chemical abundance pattern suggests that J2114$-$0616 can
be classified as CEMP-r/s star. In addition, the star J1054+0528 can be
classified as a CEMP-rI star, with [Eu/Fe]=0.44 and [Ba/Fe]=$-$0.52. The other
stars in our sample show no enhancements in neutron-capture elements and can be
classified as CEMP-no stars. We also performed a kinematic and dynamical
analysis of the sample stars based on Gaia DR2 data. The kinematic parameters,
orbits, and binding energy of these stars, show that J2114$-$0616 is member of
the outer halo population, while the remaining stars belong to the inner halo
population but with an accreted origin. Collectively, these results add
important constraints on the origin and evolution of CEMP stars as well as on
their possible formation scenarios.
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