J/A+A/580/A17 α-element abundances of Cepheid stars (Genovali+, 2015)
On the alpha-element gradients of the Galactic thin disk using Cepheids.
Genovali K., Lemasle B., da Silva R., Bono G., Fabrizio M., Bergemann M.,
Buonanno R., Ferraro I., Francois P., Iannicola G., Inno L., Laney C.D.,
Kudritzki R.-P., Matsunaga N., Nonino M., Primas F., Romaniello M.,
Urbaneja M.A., Thevenin F.
<Astron. Astrophys. 580, A17 (2015)>
=2015A&A...580A..17G 2015A&A...580A..17G
ADC_Keywords: Stars, variable ; Milky Way ; Abundances ; Spectroscopy
Keywords: stars: abundances - stars: variables: Cepheids -
stars: oscillations - Galaxy: disk -
open clusters and associations: general
Abstract:
We present new homogeneous measurements of Na, Al, and three
alpha-elements (Mg, Si, Ca) for 75 Galactic Cepheids, complemented
with Cepheid abundances available in the literature, for a total of
439 stars. The abundances are based on high spectral resolution
(R∼38000) and high signal-to-noise ratio (S/N∼50-300) spectra
collected with UVES at ESO VLT. Special attention was given to
providing a homogeneous abundance scale for these five elements plus
iron. In addition, accurate Galactocentric distances (RG) based on
near-infrared photometry are also available for all the Cepheids in
the sample. We found that these five elements display well-defined
linear radial gradients and modest standard deviations over the entire
range of RG. The [element/Fe] abundance ratios are constant across the
entire thin disk and over the entire period range; only the Ca radial
distribution shows marginal evidence of slopes. These results indicate
that the chemical enrichment history of iron and of the quoted
elements has been quite similar across the four quadrants of the
Galactic thin disk, and very homogenous within the range in age
covered by the Cepheids (∼10-300Myr). Finally, we also find that
Cepheid abundances agree with similar abundances for thin and thick
disk dwarf stars, and they follow the typical Mg-Al and Na-O
correlations.
Description:
The abundances of Fe, Na, Al, and three alpha elements (Mg, Si, Ca)
for our sample of 75 Cepheids plus data available in the literature
for other 364 Cepheids are shown. We first show the abundances derived
based on individual spectra for the 75 stars, then the averaged
values, and finally the data from the literature. The original
abundances available in the literature were rescaled according to the
zero-point differences listed in Table 3. The priority was given in
the following order: we first adopt the abundances provided by our
group, this study (TS) and Lemasle et al. (2013A&A...558A..31L 2013A&A...558A..31L, LEM),
and then those provided by the other studies, Luck & Lambert
(2011AJ....142..136L 2011AJ....142..136L, LIII), Luck et al. (2011AJ....142...51L 2011AJ....142...51L, LII),
and Yong et al. (2006AJ....131.2256Y 2006AJ....131.2256Y, YON).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 103 122 Fe, Na, Al, Mg, Si, and Ca abundances for the
75 Cepheids based on individual spectra
table2.dat 94 75 Mean abundances of Fe, Na, Al, Mg, Si, and Ca
for the 75 Cepheids
table5.dat 96 439 Na, Al, Mg, Si, and Ca abundances for the whole
sample of 439 Galactic Cepheids (the current
75 plus 364 from the literature)
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See also:
J/AJ/142/51 : Galactic Cepheids abundance variations (Luck+, 2011)
J/AJ/142/136 : Spectroscopy of Cepheids. l=30-250° (Luck+, 2011)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Name Cepheid name
11- 19 F9.3 d MJD Observation date (Modified Julian Day)
21- 25 F5.2 [Sun] [Fe/H] [-0.31/0.55] Metallicity [Fe/H] based on
FeI and FeII
27- 30 F4.2 [Sun] e_[Fe/H] [0.01/0.3] Standard deviation on [Fe/H]
32- 34 I3 --- NFe1 [8/118] Number of FeI lines used
36- 37 I2 --- NFe2 [0/14] Number of FeII lines used
39- 43 F5.2 [Sun] [Na/H] [-0.3/1]? Sodium abundance [Na/H]
45- 48 F4.2 [Sun] e_[Na/H] [0/0.4]? Dispersion around the mean on [Na/H]
50 I1 --- NNa [1/2]? Number of NaI lines used
52- 56 F5.2 [Sun] [Al/H] [-0.4/1]? Aluminum abundance [Al/H]
58- 61 F4.2 [Sun] e_[Al/H] [0/0.4]? Dispersion around the mean on [Al/H]
63 I1 --- NAl [1/6]? Number of AlI lines used
65- 69 F5.2 [Sun] [Mg/H] [-0.4/0.6]? Magnesium abundance [Mg/H]
71- 74 F4.2 [Sun] e_[Mg/H] [0/0.6]? Dispersion around the mean on [Mg/H]
76 I1 --- NMg [1]? Number of MgI lines used
78- 82 F5.2 [Sun] [Si/H] [-0.4/0.7]? Silicon abundance [Si/H]
84- 87 F4.2 [Sun] e_[Si/H] [0/0.4]? Dispersion around the mean on [Si/H]
89- 90 I2 --- NSi [1/14]? Number of SiI lines used
92- 96 F5.2 [Sun] [Ca/H] [-0.7/0.5]? Calcium abundance [Ca/H]
98-101 F4.2 [Sun] e_[Ca/H] [0/0.4]? Dispersion around the mean on [Ca/H]
103 I1 --- NCa [1/7]? Number of CaI lines used
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Name Cepheid name
11- 16 F6.4 [d] logP [0.36/1.54] Logarithmic pulsation period
18- 22 I5 pc Rgc [4657/14344] Galactocentric distance
24- 26 I3 pc e_Rgc [358/473] Error in the Galactocentric distance
28- 32 F5.2 [Sun] [Fe/H] [-0.31/0.55] Metallicity [Fe/H] based on
FeI and FeII
34- 37 F4.2 [Sun] e_[Fe/H] [0.03/0.2]Standard deviation on [Fe/H]
39- 43 F5.2 [Sun] [Na/H] [-0.3/1]? Sodium abundance [Na/H]
45- 48 F4.2 [Sun] e_[Na/H] [0/0.4]? Dispersion around the mean on [Na/H]
50- 54 F5.2 [Sun] [Al/H] [-0.4/1]? Aluminum abundance [Al/H]
56- 59 F4.2 [Sun] e_[Al/H] [0/0.4]? Dispersion around the mean on [Al/H]
61- 65 F5.2 [Sun] [Mg/H] [-0.4/0.6]? Magnesium abundance [Mg/H]
67- 70 F4.2 [Sun] e_[Mg/H] [0/0.6]? Dispersion around the mean on [Mg/H]
72- 76 F5.2 [Sun] [Si/H] [-0.4/0.7]? Silicon abundance [Si/H]
78- 81 F4.2 [Sun] e_[Si/H] [0/0.4]? Dispersion around the mean on [Si/H]
83- 87 F5.2 [Sun] [Ca/H] [-0.7/0.5]? Calcium abundance [Ca/H]
89- 92 F4.2 [Sun] e_[Ca/H] [0/0.4]? Dispersion around the mean on [Ca/H]
94 I1 --- Ns [1/6]? Number of spectra available
for each star
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1 A1 --- n_Name [*] * for observed Cepheids
3- 11 A9 --- Name Cepheid name
13- 17 F5.2 [Sun] [Na/H]o ? Na/H abundance from literature (original)
19- 23 F5.2 [Sun] [Na/H] ? Na/H abundance from literature (rescaled)
25- 28 A4 --- r_[Na/H] ? Reference for the Na literature abundances (1)
30- 34 F5.2 [Sun] [Al/H]o ? Al/H abundance from literature (original)
36- 40 F5.2 [Sun] [Al/H] ? Al/H abundance from literature (rescaled)
42- 45 A4 --- r_[Al/H] ? Reference for the Al literature abundances (1)
47- 51 F5.2 [Sun] [Mg/H]o ? Mg/H abundance from literature (original)
53- 57 F5.2 [Sun] [Mg/H] ? Mg/H abundance from literature (rescaled)
59- 62 A4 --- r_[Mg/H] ? Reference for the Mg literature abundances (1)
64- 68 F5.2 [Sun] [Si/H]o Si/H abundance from literature (original)
70- 74 F5.2 [Sun] [Si/H] Si/H abundance from literature (rescaled)
76- 79 A4 --- r_[Si/H] Reference for the Si literature abundances (1)
81- 85 F5.2 [Sun] [Ca/H]o Ca/H abundance from literature (original)
87- 91 F5.2 [Sun] [Ca/H] Ca/H abundance from literature (rescaled)
93- 96 A4 --- r_[Ca/H] Reference for the Ca literature abundances (1)
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Note (1): The references are as follows:
TS = this study
LII = Luck et al., 2011AJ....142...51L 2011AJ....142...51L, Cat. J/AJ/142/51
LIII = Luck & Lambert,2011AJ....142..136L 2011AJ....142..136L, Cat. J/AJ/142/136
LEM = Lemasle et al. 2013A&A...558A..31L 2013A&A...558A..31L
YON = Yong et al., 2006AJ....131.2256Y 2006AJ....131.2256Y
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Acknowledgements:
Ronaldo da Silva, ron.oliveirasilva(at)gmail.com
(End) Patricia Vannier [CDS] 10-Apr-2015