J/ApJ/875/89 Metal-poor stars with APF. I. LAMOST CEMP stars (Mardini+, 2019)
Metal-poor stars observed with the Automated Planet Finder telescope.
I. Discovery of five carbon-enhanced metal-poor stars from LAMOST.
Mardini M.K., Li H., Placco V.M., Alexeeva S., Carollo D., Taani A.,
Ablimit I., Wang L., Zhao G.
<Astrophys. J., 875, 89 (2019)>
=2019ApJ...875...89M 2019ApJ...875...89M
ADC_Keywords: Stars, metal-deficient; Equivalent widths; Spectra, optical;
Abundances
Keywords: Galaxy: halo ; stars: abundances ; stars: fundamental parameters
Abstract:
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∼2000) spectroscopic
database as metal-poor candidates and followed up with high-resolution
spectroscopy (R∼110000) 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.
Description:
We obtain high-resolution spectra (R=110000 and a slit width of
0.5mm), covering the wavelength range of 3730-9989Å, for a sample
of 12 stars, using the 2.4m Lick Automated Planet Finder (Lick/APF).
In addition, we observed the well-studied very metal-poor (VMP) star
HD2796 as a standard.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 72 6 Log of the Lick/Automated Planet Finder (APF)
observations
table2.dat 84 338 Equivalent widths of our sample
table3.dat 70 6 Stellar parameters of the program stars
table7.dat 90 6 Parallaxes, proper motions, and distances
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See also:
I/347 : Distances to 1.33 billion stars in Gaia DR2 (Bailer-Jones+, 2018)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
V/153 : LAMOST DR4 catalogs (Luo+, 2018)
J/A+A/354/169 : Metal-poor field stars abundances (Gratton+, 2000)
J/A+A/416/1117 : Abundances in the early Galaxy (Cayrel+, 2004)
J/ApJ/655/492 : Equivalent widths of 26 metal-poor stars (Aoki+, 2007)
J/ApJ/658/1203 : Nitrogen-enhanced metal-poor stars (Johnson+, 2007)
J/A+A/503/541 : Neutral Li in late-type stars (Lind+, 2009)
J/A+A/509/A93 : Carbon-enhanced metal-poor stars (Masseron+, 2010)
J/AJ/141/175 : Abundances in M15 RGB/RHB stars (Sobeck+, 2011)
J/AJ/145/13 : Metal-poor stars from SDSS/SEGUE. I. (Aoki+, 2013)
J/ApJ/769/57 : Equivalent widths of metal-poor stars (Frebel+, 2013)
J/ApJ/773/33 : Analysis of the metal-poor subgiant BD+44 493 (Ito+, 2013)
J/ApJ/762/26 : Most metal-poor stars. II. Galactic halo stars (Yong+, 2013)
J/ApJ/788/180 : Very metal-poor stars in the MW's halo (Carollo+, 2014)
J/ApJ/797/21 : Carbon-enhanced metal-poor stars (Placco+, 2014)
J/AJ/147/136 : Stars of very low metal abundance. VI. (Roederer+, 2014)
J/A+A/581/A22 : 67 CEMP-s stars model analysis (Abate+, 2015)
J/ApJ/798/110 : Equivalent widths of LAMOST metal-poor stars (Li+, 2015)
J/ApJ/812/109 : HST & Keck spectrosc. of bright CEMP-s stars (Placco+, 2015)
J/ApJ/821/37 : Abundances of metal-poor star HD 94028 (Roederer+, 2016)
J/MNRAS/456/1221 : FGK dwarfs atmospheric parameters (Ryabchikova+, 2016)
J/ApJ/833/20 : Carbon-enhanced metal-poor (CEMP) star abund. (Yoon+, 2016)
J/ApJ/833/225 : -2.6≤[Fe/H]≤0.2 F and G dwarfs. II. (Zhao+, 2016)
J/A+A/604/A129 : The MW halo & its dwarf satellites (Mashonkina+, 2017)
J/A+A/614/A68 : Carbon-enhanced metal-poor stars sample (Caffau+, 2018)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 I1 --- Seq [1/6] Running sequence number
3- 12 A10 --- ID Star identifier
14- 24 A11 "date" Date UT date of observation
26- 27 I2 h RAh Hour of right ascension (J2000)
29- 30 I2 min RAm Minute of right ascension (J2000)
32- 36 F5.2 s RAs Second of right ascension (J2000)
38 A1 --- DE- Sign of declination (J2000)
39- 40 I2 deg DEd Degree of declination (J2000)
42- 43 I2 arcmin DEm Arcminute of declination (J2000)
45- 48 F4.1 arcsec DEs Arcsecond of declination (J2000)
50- 54 F5.2 mag rmag [8.5/12.8] r-band magnitude
56- 59 I4 s Exp Exposure time
60 A1 --- --- [x]
61 I1 --- o_Exp Number of exposures
63- 64 I2 pix-1 S/N [40/47] Signal to noise ratio per pixel
measured at λ∼4500Å
66- 72 F7.2 km/s HRV [-339.4/82.4] Heliocentric radial velocity
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 F7.2 10-10m lambda [4023/6970] Wavelength, Angstroms
9- 13 A5 --- Ion Ion identifier
15- 18 F4.2 eV ExPot [0/4.35]? Excitation potential, Χ
20- 24 F5.2 [-] log(gf) [-4.95/0.61]? Log of oscillator strength
26- 30 F5.1 10-13m EW1 [1.6/260.2]? Equivalent width in HD2796
in mAngstrom units
32- 34 A3 --- f_EW1 [syn ] syn=synthetic derived linewidth in EW1
36- 40 F5.1 10-13m EW2 [1.1/145.6]? Equivalent width in J1054+0528
in mAngstrom units
42- 44 A3 --- f_EW2 [syn ] syn=synthetic derived linewidth in EW2
46- 50 F5.1 10-13m EW3 [1.7/147.8]? Equivalent width in J1529+0804
in mAngstrom units
52- 54 A3 --- f_EW3 [syn ] syn=synthetic derived linewidth in EW3
56- 60 F5.1 10-13m EW4 [1.3/232.1]? Equivalent width in J1645+4357
in mAngstrom units
62- 64 A3 --- f_EW4 [syn ] syn=synthetic derived linewidth in EW4
66- 70 F5.1 10-13m EW5 [6.4/267]? Equivalent width in J2114-0616
in mAngstrom units
72- 74 A3 --- f_EW5 [syn ] syn=synthetic derived linewidth in EW5
76- 80 F5.1 10-13m EW6 [1.1/218.5]? Equivalent width in J2216+2232
in mAngstrom units
82- 84 A3 --- f_EW6 [syn ] syn=synthetic derived linewidth in EW6
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- ID Star identifier
12- 15 I4 K Teff [4810/5085] Lick/APF (adopted) effective
temperature
17- 20 F4.2 [cm/s2] logg [1/2] Lick/APF (adopted) log of
surface gravity
22- 26 F5.2 [Sun] [Fe/H] [-3.3/-2.4] Lick/APF (adopted) metallicity
28- 31 F4.2 km/s Vt [1.79/2.93] Lick/APF microturbulent velocity
(ξ)
33- 36 I4 K Teff2 [4377/5094]? LAMOST effective temperature
38- 41 F4.2 [cm/s2] logg2 [1.54/2.65]? LAMOST log of surface gravity
43- 47 F5.2 [Sun] [Fe/H]2 [-3.3/-2.9]? LAMOST metallicity
49- 52 I4 K Teff3 [4870/5080] Gaia DR2 effective temperature
54- 57 F4.2 [cm/s2] logg3 [1.39/2.15] Gaia DR2 log of surface gravity (1)
59- 62 I4 K Teffp [4652/4981]? Photometric effective temperature
64- 70 F7.2 [10-7W] logL [132/1014] Log of luminosity in erg/s
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Note (1): logg3 was measured using parallaxes adopted from Gaia DR2 and
a stellar mass of ∼0.8M☉.
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Byte-by-byte Description of file: table7.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- ID Star identifier
12- 30 I19 --- Gaia Gaia DR2 identifier
32- 37 F6.4 mas plx [0.045/1.5] Gaia DR2 (I/345) parallax
39- 44 F6.4 mas e_plx [0.02/0.07] plx uncertainty
46- 52 F7.3 mas/yr pmRA [-20.5/0.4] Gaia DR2 proper motion in RA
54- 58 F5.3 mas/yr e_pmRA [0.03/0.2] pmRA uncertainty
60- 66 F7.3 mas/yr pmDE [-51.1/-1.4] Gaia DR2 proper motion in DEC
68- 72 F5.3 mas/yr e_pmDE [0.04/0.09] pmDE uncertainty
74- 78 F5.3 kpc Dist [0.66/8.4] Gaia distance
from Bailer-Jones+, 2018, I/347
80- 84 F5.3 kpc e_Dist [0.027/1] 16th percentile confidence interval
on Dist
86- 90 F5.3 kpc E_Dist [0.028/1.3] 84th percentile confidence interval
on Dist
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 07-Sep-2020