J/MNRAS/476/724 EW of 4 primary stars and the Sun (Kong+, 2018)
Chemical abundances of primary stars in the Sirius-like binary systems.
Kong X.M., Zhao G., Zhao J.K., Shi J.R., Bharat Kumar Y., Wang L.,
Zhang J.B., Wang Y., Zhou Y.T.
<Mon. Not. R. Astron. Soc., 476, 724-740 (2018)>
=2018MNRAS.476..724K 2018MNRAS.476..724K (SIMBAD/NED BibCode)
ADC_Keywords: Stars, barium ; Abundances, peculiar
Keywords: stars: abundances - binaries: general - stars: chemically peculiar -
stars: fundamental parameters - white dwarfs
Abstract:
Study of primary stars lying in Sirius-like systems with various
masses of white dwarf (WD) companions and orbital separations is one
of the key aspects to understand the origin and nature of barium (Ba)
stars. In this paper, based on high-resolution and high-S/N spectra,
we present systematic analysis of photospheric abundances for 18 FGK
primary stars of Sirius-like systems including six giants and 12
dwarfs. Atmospheric parameters, stellar masses, and abundances of 24
elements (C, Na, Mg, Al, Si, S, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni,
Cu, Sr, Y, Zr, Ba, La, Ce, and Nd) are determined homogeneously. The
abundance patterns in these sample stars show that most of the
elements in our sample follow the behaviour of field stars with
similar metallicity. As expected, s-process elements in four known Ba
giants show overabundance. A weak correlation was found between
anomalies of s-process elemental abundance and orbital separation,
suggesting that the orbital separation of the binaries could not be
the main constraint to differentiate strong Ba stars from mild Ba
stars. Our study shows that the large mass (>0.51M☉) of a WD
companion in a binary system is not a sufficient condition to form a
Ba star, even if the separation between the two components is small.
Although not sufficient, it seems to be a necessary condition since Ba
stars with lower mass WDs in the observed sample were not found. Our
results support that [s/Fe] and [hs/ls] ratios of Ba stars are
anti-correlated with the metallicity. However, the different levels of
s-process overabundance among Ba stars may not be dominated mainly by
the metallicity.
Description:
This paper presents a complete analysis of chemical abundances in a
sample of 18 FGK stars belonging to binary systems with a white dwarf
(Sirius-like systems). The purpose of the work is to compare the
characteristics of those systems to try to understand what is
necessary to produce a Ba-rich star. We show that the orbital
separation of these systems is not important to determine whether a
star becomes a Ba star. We also conclude that a companion white dwarf
with a large mass is not enough to produce such objects either.
Objects:
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RA (J2000) DE Designation(s)
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22 19 34.36 +21 22 01.8 BD+20 5125 = HIP 110218
14 57 53.57 +29 52 32.5 BD+30 2592 = HIP 73224
07 04 02.88 +71 11 41.5 BD+71 380 = HIP 34082
05 53 58.75 +12 25 10.0 HD 39570 = HIP 27878
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stars.dat 40 6 List of studied stars
table3.dat 62 1692 All atomic-line data used and their corresponding
EWs and abundances of program stars and the Sun
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Byte-by-byte Description of file: stars.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Star name, as in table3.dat
14- 15 I2 h RAh ? Simbad right ascension (J2000)
17- 18 I2 min RAm ? Simbad right ascension (J2000)
20- 24 F5.2 s RAs ? Simbad right ascension (J2000)
26 A1 --- DE- Declination sign (J2000)
27- 28 I2 deg DEd ? Declination (J2000)
30- 31 I2 arcmin DEm ? Declination (J2000)
33- 36 F4.1 arcsec DEs ? Declination (J2000)
38- 40 I3 --- N Number of atomic-line data in table3.dat
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Star Star name (1)
13- 16 A4 --- Ion Ion designation
20- 27 F8.3 0.1nm lambda Wavelength
33- 37 F5.3 eV EP Excitation potential
40- 45 F6.3 [-] loggf log of Oscillator Strength
51- 55 F5.1 0.1nm EW Line equivalent width
58- 62 F5.3 --- A(X) Absolute element abundances
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Note (1): BD+20 5125, BD+30 2592, BD+71 380, HD 39570, Sun(ARCES) and Sun(CES).
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 13-Apr-2021