J/MNRAS/454/1976 Abundance ratio for 5 local stellar associations (Reddy+, 2015)
Local associations and the barium puzzle.
Reddy A.B.S., Lambert D.L.
<Mon. Not. R. Astron. Soc., 454, 1976-1991 (2015)>
=2015MNRAS.454.1976R 2015MNRAS.454.1976R (SIMBAD/NED BibCode)
ADC_Keywords: Associations, stellar ; Stars, nearby ; Spectroscopy ;
Equivalent widths ; Abundances
Keywords: stars: abundances -
open clusters and associations: individual: Argus, Carina-Near,
Hercules-Lyra, Orion and Subgroup B4
Abstract:
We have observed high-dispersion echelle spectra of main-sequence
stars in five nearby young associations - Argus, Carina-Near,
Hercules-Lyra, Orion and Subgroup B4 - and derived abundances for
elements ranging from Na to Eu. These are the first chemical abundance
measurements for two of the five associations, while the remaining
three associations are analysed more extensively in our study. Our
results support the presence of chemical homogeneity among association
members with a typical star-to-star abundance scatter of about 0.06dex
or less over many elements. The five associations show log ε(Li)
consistent with their age and share a solar chemical composition for
all elements with the exception of Ba. We find that all the heavy
elements (Y, Zr, La, Ce, Nd, Sm and Eu) exhibit solar ratios, i.e.
[X/Fe]≃0, while Ba is overabundant by about 0.2-0.3dex. The origin of
the overabundance of Ba is a puzzle. Within the formulation of the
s-process, it is difficult to create a higher Ba abundance without a
similar increase in the s-process contributions to other heavy elements
(La-Sm). Given that Ba is represented by strong lines of Ba II and
La-Sm are represented by rather weak ionized lines, the suggestion, as
previously made by other studies, is that the Ba abundance may be
systematically overestimated by standard methods of abundance analysis
perhaps because the upper reaches of the stellar atmospheres are
poorly represented by standard model atmospheres. A novel attempt to
analyse the Ba I line at 5535Å gives a solar Ba abundance for stars
with effective temperatures hotter than about 5800K but increasingly
subsolar Ba abundances for cooler stars with apparent Ba deficiencies
of 0.5dex at 5100K. This trend with temperature may signal a serious
non-local thermodynamical equilibrium effect on the Ba I line.
Description:
In this paper, we have performed a homogeneous and a comprehensive
abundance analysis using high-resolution spectroscopy. High-resolution
and high signal-to-noise (S/N) spectra of the program stars were obtained
during the nights of 2015 February 10-11 with the Robert G. Tull coude
cross-dispersed echelle spectrograph (Tull et al. 1995PASP..107..251T 1995PASP..107..251T)
of the 2.7 m Harlan J. Smith reflector at the McDonald Observatory. We
employed a Tektronix 2048x2048 24 µm pixel, backside illuminated
and anti-reflection coated CCD as a detector and an R2 echelle grating
with 52.67 grooves/mm with exposures centred at 5060 Å.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 78 11 Targeted stellar associations and their
properties from the literature
table3.dat 89 323 The line list for all members of associations
analysed in this paper
table5.dat 103 29 Elemental abundance ratios, [X/Fe], for
individual stars in Argus and Carina-Near
associations
table6.dat 101 28 Elemental abundance ratios, [X/Fe], for
individual stars in associations Orion and
Subgroup B4
table7.dat 75 30 Elemental abundance ratios, [X/Fe], for
individual stars in the Hercules-Lyra
association
table9.dat 70 27 Mean abundance ratios, [X/Fe], for the Argus,
Carina-Near, Hercules-Lyra, Orion and
Subgroup B4 associations
table11.dat 77 19 Mean elemental abundance ratios, [X/Fe], for our
sample of five associations and the comparison
samples
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See also:
J/AJ/129/1063 : Abundances of stars within 15pc of the Sun (Luck+, 2005)
J/AJ/133/2464 : Parameters and abundances of nearby giants (Luck+, 2007)
J/A+A/480/735 : Young local stellar associations (Fernandez+, 2008)
J/AJ/142/136 : Spectroscopy of Cepheids. l=30-250° (Luck+, 2011)
J/MNRAS/419/1350 : Red giants abundances in 4 open clusters (Reddy+, 2012)
J/MNRAS/431/1005 : IC 2391 and Argus young stars (de Silva+, 2013)
J/MNRAS/431/3338 : Abundances of red giants in open clusters (Reddy+, 2013)
J/A+A/562/A71 : Chemical abundances of solar neighbourhood dwarfs
(Bensby+, 2014)
J/MNRAS/437/2106 : Barium abundance in Galactic Cepheids (Andrievsky+, 2014)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 A19 --- Assoc Stellar association name
21- 22 I2 pc DistA Distance of stellar association
24- 26 I3 Myr Age Age
28- 40 A13 --- Star Star name
42- 43 I2 h RAh Hour of Right Ascension (J2000)
45- 46 I2 min RAm Minute of Right Ascension (J2000)
48- 52 F5.2 s RAs Second of Right Ascension (J2000)
54 A1 --- DE- Sign of the Declination (J2000)
55- 56 I2 deg DEd Degree of Declination (J2000)
58- 59 I2 arcmin DEm Arcminute of Declination (J2000)
61- 65 F5.2 arcsec DEs Arcsecond of Declination (J2000)
67 A1 --- l_DistS [~] Limit flag on DistS
68- 71 F4.1 pc DistS Distance of star
73- 76 A4 --- SpT Spectral type
78 I1 --- Ref [1/4] Reference for the target selection (1)
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Note (1): Reference as follows:
1 = De Silva et al. (2013, J/MNRAS/431/1005);
2 = Zuckerman et al. (2006ApJ...649L.115Z 2006ApJ...649L.115Z);
3 = Lopez-Santiago et al. (2006ApJ...643.1160L 2006ApJ...643.1160L);
4 = Cunha, Smith & Lambert (1995ApJ...452..634C 1995ApJ...452..634C).
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Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 F7.2 0.1nm lambda [4520.23/8838.43] Wavelength λ (Å)
9- 12 F4.1 --- Species Species identification (1)
14- 17 F4.2 eV LEP Lower Excitation potential of the transition (2)
19- 23 F5.2 [-] log(gf) ? Log of the oscillator strength
25- 29 F5.1 0.1pm EW1 ? Equivalent width for the star BD-20 2977
(mÅ) (3)
31- 35 F5.1 0.1pm EW2 ? Equivalent width for the star HD 61005 (mÅ)
(3)
37- 41 F5.1 0.1pm EW3 ? Equivalent width for the star HD 103742 (mÅ)
(3)
43- 47 F5.1 0.1pm EW4 ? Equivalent width for the star HD 103743 (mÅ)
(3)
49- 53 F5.1 0.1pm EW5 ? Equivalent width for the star HD 166 (mÅ)
(3)
55- 59 F5.1 0.1pm EW6 ? Equivalent width for the star HD 10008 (mÅ)
(3)
61- 65 F5.1 0.1pm EW7 ? Equivalent width for the star HD 17925 (mÅ)
(3)
67- 71 F5.1 0.1pm EW8 ? Equivalent width for the star Parenago 2339
(mÅ) (3)
73- 77 F5.1 0.1pm EW9 ? Equivalent width for the star Parenago 2374
(mÅ) (3)
79- 83 F5.1 0.1pm EW10 ? Equivalent width for the star HD 113449 (mÅ)
(3)
85- 89 F5.1 0.1pm EW11 ? Equivalent width for the star HD 152555 (mÅ)
(3)
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Note (1): The integer component of the species indicates the atomic number,
and the decimal component indicates the ionization state
(0=neutral, 1=singly ionized).
Note (2): All the lines are arranged in the order of their increasing lower
excitation potential (LEP).
Note (3): The EW given for the synthesized line (Li I, Mn I and Ba II) is
the blend equivalent width.
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Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- Ion Species identifier
17- 21 F5.2 --- [X/Fe]2 ? Elemental abundance ratio [X/Fe] for
the star HD 61005
23- 26 F4.2 --- e_[X/Fe]2 ? Uncertainty in [X/Fe]2
27 A1 --- n_[X/Fe]2 [*] Note on [X/Fe]2 (G1)
29- 31 I3 --- o_[X/Fe]2 ? Number of lines used in calculating the
abundance of that element
33- 37 F5.2 --- [X/Fe]1 ? Elemental abundance ratio [X/Fe] for
the star BD-20 2977
39- 42 F4.2 --- e_[X/Fe]1 ? Uncertainty in [X/Fe]1
43 A1 --- n_[X/Fe]1 [*] Note on [X/Fe]1 (G1)
45- 46 I2 --- o_[X/Fe]1 ? Number of lines used in calculating the
abundance of that element
48- 52 F5.2 --- [X/Fe]A ? Average elemental abundance ratio [X/Fe]
for the Argus association
54- 57 F4.2 --- e_[X/Fe]A ? Uncertainty in [X/Fe]A
58 A1 --- n_[X/Fe]A [*] Note on [X/Fe]A (G1)
61- 65 F5.2 --- [X/Fe]3 Elemental abundance ratio [X/Fe] for the
star HD 103742
67- 70 F4.2 --- e_[X/Fe]3 ? Uncertainty in [X/Fe]3
71 A1 --- n_[X/Fe]3 [*] Note on [X/Fe]3 (G1)
73- 75 I3 --- o_[X/Fe]3 ? Number of lines used in calculating the
abundance of that element
77- 81 F5.2 --- [X/Fe]4 ? Elemental abundance ratio [X/Fe] for the
star HD 103743
83- 86 F4.2 --- e_[X/Fe]4 ? Uncertainty in [X/Fe]4
87 A1 --- n_[X/Fe]4 [*] Note on [X/Fe]4 (G1)
89- 91 I3 --- o_[X/Fe]4 ? Number of lines used in calculating the
abundance of that element
93- 97 F5.2 --- [X/Fe]C ? Average elemental abundance ratio [X/Fe]
for the Carina-Near association
99-102 F4.2 --- e_[X/Fe]C ? Uncertainty in [X/Fe]C
103 A1 --- n_[X/Fe]C [*] Note on [X/Fe]C (G1)
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Byte-by-byte Description of file: table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- Ion Species identifier
17- 21 F5.2 --- [X/Fe]8 ? Elemental abundance ratio [X/Fe] for
the star Parenago 2339
23- 26 F4.2 --- e_[X/Fe]8 ? Uncertainty in [X/Fe]8
27 A1 --- n_[X/Fe]8 [*] Note on [X/Fe]8 (G1)
29- 30 I2 --- o_[X/Fe]8 ? Number of lines used in calculating the
abundance of that element
32- 36 F5.2 --- [X/Fe]9 ? Elemental abundance ratio [X/Fe] for
the star Parenago 2374
38- 41 F4.2 --- e_[X/Fe]9 ? Uncertainty in [X/Fe]9
42 A1 --- n_[X/Fe]9 [*] Note on [X/Fe]9 (G1)
44- 46 I3 --- o_[X/Fe]9 ? Number of lines used in calculating the
abundance of that element
48- 52 F5.2 --- [X/Fe]O ? Average elemental abundance ratio [X/Fe]
for the Orion association
54- 57 F4.2 --- e_[X/Fe]O ? Uncertainty in [X/Fe]O
58 A1 --- n_[X/Fe]O [*] Note on [X/Fe]O (G1)
60- 64 F5.2 --- [X/Fe]10 ? Elemental abundance ratio [X/Fe] for the
star HD 113449
66- 69 F4.2 --- e_[X/Fe]10 ? Uncertainty in [X/Fe]10
70 A1 --- n_[X/Fe]10 [*] Note on [X/Fe]10 (G1)
72- 74 I3 --- o_[X/Fe]10 ? Number of lines used in calculating the
abundance of that element
76- 80 F5.2 --- [X/Fe]11 ? Elemental abundance ratio [X/Fe] for the
star HD 152555
82- 85 F4.2 --- e_[X/Fe]11 ? Uncertainty in [X/Fe]11
86 A1 --- n_[X/Fe]11 [*] Note on [X/Fe]11 (G1)
88- 89 I2 --- o_[X/Fe]11 ? Number of lines used in calculating the
abundance of that element
91- 95 F5.2 --- [X/Fe]S ? Average elemental abundance ratio [X/Fe]
for the Subgroup B4 association
97-100 F4.2 --- e_[X/Fe]S ? Uncertainty in [X/Fe]S
101 A1 --- n_[X/Fe]S [*] Note on [X/Fe]S (G1)
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Byte-by-byte Description of file: table7.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- Ion Species identifier
17- 21 F5.2 --- [X/Fe]5 ? Elemental abundance ratio [X/Fe] for
the star HD 166
23- 26 F4.2 --- e_[X/Fe]5 ? Uncertainty in [X/Fe]5
27 A1 --- n_[X/Fe]5 [*] Note on [X/Fe]5 (G1)
29- 31 I3 --- o_[X/Fe]5 ? Number of lines used in calculating the
abundance of that element
33- 37 F5.2 --- [X/Fe]6 ? Elemental abundance ratio [X/Fe] for
the star HD 10008
39- 42 F4.2 --- e_[X/Fe]6 ? Uncertainty in [X/Fe]6
43 A1 --- n_[X/Fe]6 [*] Note on [X/Fe]6 (G1)
45- 47 I3 --- o_[X/Fe]6 ? Number of lines used in calculating the
abundance of that element
49- 53 F5.2 --- [X/Fe]7 ? Elemental abundance ratio [X/Fe] for
the star HD 17925
55- 58 F4.2 --- e_[X/Fe]7 ? Uncertainty in [X/Fe]7
59 A1 --- n_[X/Fe]7 [*] Note on [X/Fe]7 (G1)
61- 63 I3 --- o_[X/Fe]7 ? Number of lines used in calculating the
abundance of that element
65- 69 F5.2 --- [X/Fe]H ? Average elemental abundance ratio [X/Fe] for
the Hercules-Lyra association
71- 74 F4.2 --- e_[X/Fe]H ? Uncertainty in [X/Fe]H
75 A1 --- n_[X/Fe]H [*] Note on [X/Fe]H (G1)
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Byte-by-byte Description of file: table9.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- Ion Species identifier
12- 16 F5.2 --- [X/Fe]A ? Mean abundance ratio [X/Fe] for the Argus
association
18- 21 F4.2 --- e_[X/Fe]A ? Uncertainty in [X/Fe]A
22 A1 --- n_[X/Fe]A [*] Note on [X/Fe]A (G1)
24- 28 F5.2 --- [X/Fe]C Mean abundance ratio [X/Fe] for the
Carina-Near association
30- 33 F4.2 --- e_[X/Fe]C ? Uncertainty in [X/Fe]C
34 A1 --- n_[X/Fe]C [*] Note on [X/Fe]C (G1)
36- 40 F5.2 --- [X/Fe]H Mean abundance ratio [X/Fe] for the
Hercules-Lyra association
42- 45 F4.2 --- e_[X/Fe]H ? Uncertainty in [X/Fe]H
46 A1 --- n_[X/Fe]H [*] Note on [X/Fe]H (G1)
48- 52 F5.2 --- [X/Fe]O ? Mean abundance ratio [X/Fe] for the Orion
association
54- 57 F4.2 --- e_[X/Fe]O ? Uncertainty in [X/Fe]O
58 A1 --- n_[X/Fe]O [*] Note on [X/Fe]O (G1)
60- 64 F5.2 --- [X/Fe]S ? Mean abundance ratio [X/Fe] for the
Subgroup B4 association
66- 69 F4.2 --- e_[X/Fe]S ? Uncertainty in [X/Fe]S
70 A1 --- n_[X/Fe]S [*] Note on [X/Fe]S (G1)
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Byte-by-byte Description of file: table11.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 A7 --- Ion Species identifier
9- 13 F5.2 --- [X/Fe]M Mean elemental abundance ratio [X/Fe] for our
sample of five associations
15- 18 F4.2 --- e_[X/Fe]M Uncertainty in [X/Fe]M
20- 24 F5.2 --- [X/Fe]d1 ? Thin disc mean elemental abundance ratio
[X/Fe] for field dwarfs (1)
26- 29 F4.2 --- e_[X/Fe]d1 ? Uncertainty in [X/Fe]d1 (1)
31- 35 F5.2 --- [X/Fe]d2 ? Thin disc mean elemental abundance ratio
[X/Fe] for field dwarfs (2)
37- 40 F4.2 --- e_[X/Fe]d2 ? Uncertainty in [X/Fe]d2 (2)
42- 46 F5.2 --- [X/Fe]r1 ? Thin disc mean elemental abundance ratio
[X/Fe] for red giants in OCs (3)
48- 51 F4.2 --- e_[X/Fe]r1 ? Uncertainty in [X/Fe]r1 (3)
53- 57 F5.2 --- [X/Fe]r2 ? Thin disc mean elemental abundance ratio
[X/Fe] for red giants (4)
59- 62 F4.2 --- e_[X/Fe]r2 ? Uncertainty in [X/Fe]r2 (4)
64- 68 F5.2 --- [X/Fe]Ce Thin disc mean elemental abundance ratio [X/Fe]
for Cepheids (5)
70- 73 F4.2 --- e_[X/Fe]Ce Uncertainty in [X/Fe]Ce (5)
75- 77 A3 --- r_[X/Fe]Ce Reference for [X/Fe]Ce (6)
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Note (1): From Luck & Heiter (2005, J/AJ/129/1063; 2006AJ....131.3069L 2006AJ....131.3069L).
Note (2): From Bensby et al. (2014, J/A+A/562/A71).
Note (3): From Reddy et al. (2012, J/MNRAS/419/1350; 2013, J/MNRAS/431/3338)
and Reddy et al. (2015MNRAS.450.4301R 2015MNRAS.450.4301R). Red giants were taken from the
following clusters: NGC 1817 (Reddy et al. 2012, J/MNRAS/419/1350),
NGC 2251, 2482, 2527, 2539 (Reddy et al. 2013, J/MNRAS/431/3338),
NGC 1342, 1662, 1912, 2447 (Reddy et al. 2015MNRAS.450.4301R 2015MNRAS.450.4301R) and
NGC 3114 (Santrich, Pereira & Drake 2013A&A...554A...2K 2013A&A...554A...2K).
Note (4): From Luck & Heiter (2007, J/AJ/133/2464).
Note (5): From Luck & Lambert (2011, J/AJ/142/136).
Note (6): Reference as follows:
A14 = Andrievsky, Luck & Korotin (2014, J/MNRAS/437/2106).
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Global notes:
Note (G1): Note as follows:
* = Abundance calculated by synthesis while the remaining elemental abundances
were calculated using the line EWs.
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History:
From electronic version of the journal
(End) Tiphaine Pouvreau [CDS] 15-Jan-2018