J/A+A/678/A195 O, S, and Fe abundance in classical Cepheids (da Silva+, 2023)
Oxygen, sulfur, and iron radial abundance gradients of classical Cepheids across
the Galactic thin disk.
da Silva R., D'Orazi V., Palla M, Bono G., Braga V.F., Fabrizio M.,
Lemasle B., Spitoni E., Matteucci F., Joensson H., Kovtyukh V., Magrini L.,
Bergemann M., Dall'Ora M., Ferraro I., Fiorentino G., Francois P.,
Iannicola G., Inno L., Kudritzki R.-P., Matsunaga N., Monelli M., Nonino M.,
Sneden C., Storm J., Thevenin F., Tsujimoto T., Zocchi A.
<Astron. Astrophys. 678, A195 (2023)>
=2023A&A...678A.195D 2023A&A...678A.195D (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Stars, variable ; Abundances ; Spectroscopy ; Optical
Keywords: Galaxy: disk - stars: abundances - stars: fundamental parameters -
stars: variables: Cepheids
Abstract:
Classical Cepheids (CCs) are solid distance indicators and tracers of
young stellar populations. Dating back to almost one century ago, they
have been safely adopted to trace the rotation, the kinematics and the
chemical enrichment history of the Galactic thin disk. The main aim of
this investigation is to provide iron, oxygen, and sulfur abundances
for the largest and most homogeneous sample of Galactic CCs ever
analyzed (1118 spectra of 356 objects). The current sample, containing
77 CCs for which spectroscopic metal abundances are provided for the
first time, covers a wide range in Galactocentric distances, pulsation
modes, and pulsation periods. Optical, high-resolution, and high S/N
spectra collected with different spectrographs were adopted to provide
homogeneous estimates of the atmospheric parameters (effective
temperature, surface gravity, microturbulent velocity) required for
abundance determination. Individual distances are based either on
trigonometric parallaxes by Gaia DR3 or on distances based
near-infrared Period-Luminosity relations. We found that iron and
alpha-element radial gradients based on CCs display a well-defined
change in the slope for Galactocentric distances larger than ∼12kpc.
We also found that logarithmic regressions take account for the
variation of [X/H] abundances when moving from the inner to the outer
disk. Radial gradients for the same elements, but based on open
clusters covering a wide range in cluster ages, display similar
trends. This means that the flattening in the outer disk is an
intrinsic feature of the radial gradients, since it is independent of
age. Empirical evidence indicates that the S radial gradient is
steeper than the Fe radial gradient. The difference in the slope is a
factor of two in the linear fit (-0.081 vs. -0.041dex/kpc) and changes
from -1.62 to -0.91 in the logarithmic distance. Moreover, we found
that S (explosive nucleosynthesis) is, on average, under-abundant when
compared with O (hydrostatic nucleosynthesis). The difference becomes
clearer in the metal-poor regime and in dealing with the [O/Fe] and
[S/Fe] abundance ratios. We performed a detailed comparison with
Galactic chemical evolution models and we found that a constant Star
Formation Efficiency for Galactocentric distances larger than 12kpc
takes account for the flattening observed in both iron and
alpha-elements. To further constrain the impact that predicted S
yields for massive stars have on radial gradients, we adopted a "toy
model" and we found that the flattening in the outermost regions
requires a decrease of a factor of four in the current S predictions.
CCs are solid beacons to trace the recent chemical enrichment of young
stellar populations. Sulfur photospheric abundances, when compared
with other alpha-elements, have the key advantage of being a volatile
element. Therefore, stellar S abundances can be directly compared with
nebular sulfur abundances in external galaxies.
Description:
Several parameters of our sample of 379 Galactic classical Cepheids
are presented, such as the pulsation period, heliocentric and
galactocentric distances, atmospheric parameters and abundances. A
list of FeI and FeII atomic lines were used to derive the effective
temperature, surface gravity, microturbulent velocity, and metallicity
for each of the available spectra (collected with HARPS, FEROS, UVES,
and/or STELLA spectrographs). The abundance of oxygen (based on the OI
atomic line at 6300.3Å) and sulfur (based on the SI atomic line at
6757.2Å) were then derived. The mean stellar metallicity and the
mean abundances computed for each star together with the estimated
uncertainties and the number of spectra used are also presented.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 124 379 Pulsation parameters, literature Fe abundance,
and Heliocentric and Galactocentric distances
table2.dat 126 1285 Atmospheric parameters and Fe, O, and S
abundances for each spectrum
table3.dat 134 379 Mean Fe, O, and S abundances for each star
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See also:
III/283 : RAVE 6th data release (Steinmetz+, 2020)
J/AJ/142/136 : Spectroscopy of Cepheids. l=30-250° (Luck+, 2011)
J/A+A/566/A37 : Iron abundances for 42 Galactic Cepheids (Genovali+, 2014)
J/AJ/156/171 : Cepheid abund.: multiphase results + spatial gradients
(Luck, 2018)
J/MNRAS/508/4047 : 47 classical Cepheids HARPSN@TNG spectroscopy
(Ripepi+, 2021)
J/A+A/661/A104 : Physical parameters of classical Cepheids (da Silva+, 2022)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 20 A20 --- Name Cepheid name
23- 24 I2 h RAh Right ascension (J2000.0)
26- 27 I2 min RAm Right ascension (J2000.0)
29- 34 F6.3 s RAs Right ascension (J2000.0)
37 A1 --- DE- Declination sign (J2000.0)
38- 39 I2 deg DEd Declination (J2000.0)
41- 42 I2 arcmin DEm Declination (J2000.0)
44- 49 F6.3 arcsec DEs Declination (J2000.0)
52- 62 F11.7 d Period ? Pulsation period
65- 66 I2 --- Mode Pulsation mode
69- 73 F5.2 --- [Fe/H] ? Stellar metallicity [Fe/H] from literature
76- 79 F4.2 --- e_[Fe/H] ? Error in the stellar metallicity
82 I1 --- r_[Fe/H] ? Reference for metallicity from literature (1)
85- 90 I6 pc X Heliocentric distance projected on the x-axis
93- 98 I6 pc Y Heliocentric distance projected on the y-axis
101-105 I5 pc Z Heliocentric distance projected on the z-axis
108-112 I5 pc RH Heliocentric radial distance
115-119 I5 pc RG Galactocentric radial distance
122-124 I3 pc e_R ? Error in the radial distance
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Note (1): References for the metallicity as follows:
1 = Genovali et al. (2014A&A...566A..37G 2014A&A...566A..37G, Cat. J/A+A/566/A37)
2 = da Silva et al. (2022A&A...661A.104D 2022A&A...661A.104D, Cat. J/A+A/661/A104)
3 = Trentin et al. (2023MNRAS.519.2331T 2023MNRAS.519.2331T)
4 = Ripepi et al. (2021MNRAS.508.4047R 2021MNRAS.508.4047R, Cat. J/MNRAS/508/4047)
5 = Luck & Lambert (2011AJ....142..136L 2011AJ....142..136L, Cat. J/AJ/142/136)
6 = Luck (2018AJ....156..171L 2018AJ....156..171L, Cat. J/AJ/156/171)
7 = Steinmetz et al. (2020AJ....160...83S 2020AJ....160...83S, Cat. III/283)
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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- 20 A20 --- Name Cepheid name
23- 28 A6 --- Dataset Spectroscopic dataset
31- 43 F13.7 d MJD Modified Julian Date
46- 49 I4 K Teff Effective temperature
52- 55 I4 K e_Teff Error in the effective temperature
58- 60 F3.1 [cm/s2] logg ? Surface gravity
63- 65 F3.1 km/s vt ? Microturbulent velocity
68- 72 F5.2 --- FeI ? Iron abundance from FeI lines [Fe I/H]
75- 78 F4.2 --- e_FeI ? Error in the FeI abundance
81- 83 I3 --- NFeI ? Number of FeI lines adopted
86- 90 F5.2 --- FeII ? Iron abundance from FeII lines [Fe II/H]
93- 96 F4.2 --- e_FeII ? Error in the FeII abundance
99-100 I2 --- NFeII ? Number of FeII lines adopted
103-107 F5.2 --- OH ? Oxygen abundance from the 6300.3 O line [O/H]
110-113 F4.2 --- e_OH ? Error in the OI abundance
116-120 F5.2 --- SH ? Sulfur abundance from the 6757.2 S line [S/H]
123-126 F4.2 --- e_SH ? Error in the SI abundance
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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- 20 A20 --- Name Cepheid name
23- 27 F5.2 --- FeI ? Mean iron abundance from FeI lines
30- 33 F4.2 --- e_FeI ? Error in the mean FeI abundance
36- 40 F5.2 --- FeII ? Mean iron abundance from FeII lines
43- 46 F4.2 --- e_FeII ? Error in the mean FeII abundance
49- 53 F5.2 --- FeH ? Mean iron abundance from FeI, FeII lines
56- 59 F4.2 --- e_FeH ? Error in the mean Fe abundance
62- 65 F4.2 --- s_FeH ? Standard deviation of the mean Fe abundance
68- 70 I3 --- NFe Number of spectra with derived Fe abundance
73- 77 F5.2 --- OH ? Mean oxygen abundance from the OI line
80- 83 F4.2 --- e_OH ? Error in the mean O abundance
86- 89 F4.2 --- s_OH ? Standard deviation of the mean O abundance
92- 94 I3 --- NO Number of spectra with derived O abundance
97-101 F5.2 --- SH ? Mean sulfur abundance from the SI line
104-107 F4.2 --- e_SH ? Error in the mean S abundance
110-113 F4.2 --- s_SH ? Standard deviation of the mean S abundance
116-118 I3 --- NS Number of spectra with derived S abundance
121-122 I2 --- NFEROS Number of spectra from FEROS
125-126 I2 --- NHARPS Number of spectra from HARPS
129-130 I2 --- NUVES Number of spectra from UVES
133-134 I2 --- NSTELLA Number of spectra from STELLA
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Acknowledgements:
Ronaldo Oliveira da Silva, ron.oliveirasilva(at)gmail.com
(End) Patricia Vannier [CDS] 10-Aug-2023