J/ApJ/860/49 Optical spectroscopy of young α-rich stars (Matsuno+, 2018)
Optical high-resolution spectroscopy of 14 young α-rich stars.
Matsuno T., Yong D., Aoki W., Ishigaki M.N.
<Astrophys. J., 860, 49 (2018)>
=2018ApJ...860...49M 2018ApJ...860...49M
ADC_Keywords: Spectra, optical; Radial velocities; Equivalent widths; Abundances
Keywords: stars: abundances
Abstract:
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.
Description:
Observations were conducted on 2016 August 7 and 8, under good sky
conditions with HIRES on the Keck I telescope through the time
exchange program between Keck and the Subaru Telescope (proposal ID:
S16B-084). We adopt the B2 setting (R∼67000), with an echelle angle of
-0.13°, and the red cross disperser at an angle of 0.504°.
While the obtained spectra cover from 4200 to 8750Å, we refrain
from analysing the part of the spectra bluer than 5200Å to avoid
the effect of significant line blending.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 66 30 Observation log
table2.dat 58 5706 Line list, equivalent widths and FWHM
table3.dat 45 30 Stellar parameters
table4.dat 42 750 Abundances
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See also:
B/corot : CoRoT observation log (N2-4.4) (CoRoT 2016)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/ApJ/645/613 : Abundances of HD 221170 (Ivans+, 2006)
J/ApJ/667/1267 : CrI transition probabilities (Sobeck+, 2007)
J/ApJS/182/51 : Transition prob. of rare earth elements (Lawler+, 2009)
J/ApJS/194/35 : Atomic transition probabilities of Mn (Den Hartog+, 2011)
J/ApJS/208/27 : Sun and HD 84937 TiII log(gf) and abundances (Wood+, 2013)
J/A+A/562/A71 : Abundances of solar neighbourhood dwarfs (Bensby+, 2014)
J/ApJS/215/20 : Vanadium log(gf) & transition probabilities (Lawler+, 2014)
J/MNRAS/441/3127 : FeI oscillator strengths for Gaia-ESO (Ruffoni+, 2014)
J/ApJS/211/20 : NiI transition probability measurements (Wood+, 2014)
J/ApJS/220/13 : Co I transition probabilities (Lawler+, 2015)
J/A+A/586/A49 : r- & s- process elements in the MW disk (Battistini+, 2016)
J/ApJ/817/40 : High-res. NIR spectra of local giants (Feuillet+, 2016)
J/A+A/594/A43 : APOGEE/Kepler sample stars abundances (Hawkins+, 2016)
J/ApJS/228/10 : Transition prob. for 183 lines of Cr II (Lawler+, 2017)
J/MNRAS/474/2580 : Temporal evolution of neutron-capture elements
(Spina+, 2018)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 1 I1 --- Set [1/2] Subset (1=Young α-rich stars or
2=Comparison stars)
3- 17 A15 --- Name Object name used in this study (1)
19- 35 A17 --- 2MASS 2MASS identifier (JHHMMSSss+DDMMSSs)
37- 40 I4 s Exp [20/9000] Exposure time
42- 44 I3 --- SNR [145/440] Spectral signal-to-noise ratio
at 6000Å per pixel (2)
46- 49 F4.2 Msun Mass [0.6/2.7] Derived Mass (3)
51- 54 F4.2 Msun e_Mass [0.1/0.8] Uncertainty in Mass (3)
56- 60 F5.1 km/s RV1 [-86.6/69.1] Radial velocity derived
in this study
62- 66 F5.1 km/s RV2 [-85.8/71.8] Previous APOGEE radial velocity
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Note (1): Object name used in this study, including shortened versions of the
2MASS ID.
Note (2): Spectral signal-to-noise ratio at 6000Å per pixel where each pixel
corresponds to 1.33km/s.
Note (3): References for the masses:
Chiappini et al. (2015A&A...576L..12C 2015A&A...576L..12C) for CoRoT objects,
Martig et al. (2015MNRAS.451.2230M 2015MNRAS.451.2230M) for KIC objects, and
Feuillet et al. (2016, J/ApJ/817/40) for the others.
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Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- Name Object name used in this study (as in Table 1)
17- 20 A4 --- Sp Species
22- 29 F8.3 0.1nm lambda [5211.5/8717.9] Wavelength
31- 35 F5.3 eV ExPot [0/6.3] Excitation Potential
37- 42 F6.3 --- log(gf) [-6/0.7] Log of oscillator strength
44- 48 F5.1 0.1pm EW [2.2/432.7] Equivalent Width, mÅ
50- 54 F5.3 0.1nm FWHM [0.09/0.4] FWHM, Angstroms
56- 58 I3 --- Ref [1/34] References (1)
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Note (1): References as follows:
1 = Kelleher & Podobedova (2008JPCRD..37..267K 2008JPCRD..37..267K);
2 = Pehlivan Rhodin et al. (2017A&A...598A.102P 2017A&A...598A.102P);
3 = Kelleher & Podobedova (2008JPCRD..37..709K 2008JPCRD..37..709K);
4 = Kelleher & Podobedova (2008JPCRD..37.1285K 2008JPCRD..37.1285K);
5 = Nandy et al. (2012PhRvA..86e2517N 2012PhRvA..86e2517N);
6 = Smith & Raggett (1981JPhB...14.4015S 1981JPhB...14.4015S);
7 = Smith (1988JPhB...21.2827S 1988JPhB...21.2827S);
8 = Aldenius et al. (2009A&A...502..989A 2009A&A...502..989A);
9 = Lawler & Dakin (1989JOSAB...6.1457L 1989JOSAB...6.1457L);
10 = Lawler et al. (2013ApJS..205...11L 2013ApJS..205...11L);
11 = Wood et al. (2013, J/ApJS/208/27);
12 = Lawler et al. (2014, J/ApJS/215/20);
13 = Sobeck et al. (2007, J/ApJ/667/1267);
14 = Lawler et al. (2017, J/ApJS/228/10);
15 = Booth et al. (1984MNRAS.208..147B 1984MNRAS.208..147B);
16 = Den Hartog et al. (2011, J/ApJS/194/35);
17 = Ruffoni et al. (2014, J/MNRAS/441/3127);
18 = Bard et al. (1991A&A...248..315B 1991A&A...248..315B);
19 = Bard & Kock (1994A&A...282.1014B 1994A&A...282.1014B);
20 = O'Brian et al. (1991JOSAB...8.1185O 1991JOSAB...8.1185O);
21 = Blackwell et al. (1979MNRAS.186..657B 1979MNRAS.186..657B);
22 = Blackwell et al. (1980MNRAS.191..445B 1980MNRAS.191..445B);
23 = Blackwell et al. (1982MNRAS.199...43B 1982MNRAS.199...43B);
24 = Blackwell et al. (1982MNRAS.201..595B 1982MNRAS.201..595B);
25 = Blackwell et al. (1986MNRAS.220..549B 1986MNRAS.220..549B);
26 = Melendez & Barbuy (2009A&A...497..611M 2009A&A...497..611M);
27 = Lawler et al. (2015, J/ApJS/220/13);
28 = Wood et al. (2014, J/ApJS/211/20);
29 = Kock & Richter (1968ZA.....69..180K 1968ZA.....69..180K);
30 = Hannaford et al. (1982ApJ...261..736H 1982ApJ...261..736H);
31 = Klose et al. (2002JPCRD..31..217K 2002JPCRD..31..217K);
32 = Lawler et al. (2001ApJ...556..452L 2001ApJ...556..452L);
33 = Lawler et al. (2009, J/ApJS/182/51);
34 = Den Hartog et al. (2003ApJS..148..543D 2003ApJS..148..543D);
35 = Lawler et al. (2001ApJ...563.1075L 2001ApJ...563.1075L).
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Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- Name Object name used in this study (as in Table 1)
17- 17 A1 --- f_Name a= Reference star = KIC11445818
19- 22 I4 K Teff [4440/4902] Derived effective temperature
24- 25 I2 K e_Teff [16/55]? Uncertainty in Teff
27- 30 F4.2 [cm/s2] logg [1.7/3.3] Derived surface gravity
32- 35 F4.2 [cm/s2] e_logg [0.06/0.2]? Uncertainty in logg
37- 40 F4.2 km/s vt [1.5/2] Turbulent velocity
42- 45 F4.2 km/s e_vt [0.03/0.07]? Uncertainty in vt
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- Name Object name used in this study (as in Table 1)
17- 20 A4 --- Sp Species
22- 26 F5.2 [-] [X/H] [-0.7/0.5] Abundance of species relative to H
28- 31 F4.2 [-] e_[X/H] [0.02/0.2]? Uncertainty in [X/H]
33- 37 F5.2 [-] [X/Fe] [-0.2/1.1]? Abundance of species relative to Fe
39- 42 F4.2 [-] e_[X/Fe] [0.01/0.2]? Uncertainty in [X/Fe]
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 02-Jul-2019