J/MNRAS/499/2196 Carbon and nitrogen in solar twins (Botelho+, 2020)
Carbon, isotopic ratio 12C/13C, and nitrogen in solar twins: constraints
for the chemical evolution of the local disc.
Botelho R.B., Milone A. de C., Melendez J., Alves-Brito A., Spina L.,
Bean J.L.
<Mon. Not. R. Astron. Soc., 499, 2196-2213 (2020)>
=2020MNRAS.499.2196B 2020MNRAS.499.2196B (SIMBAD/NED BibCode)
ADC_Keywords: Stars, fundamental ; Abundances, [Fe/H] ; Abundances, peculiar ;
Milky Way ; Spectra, optical
Keywords: planets and satellites: formation - stars: abundance -
stars: fundamental parameters - stars: solar-type -
Galaxy: evolution - solar neighbourhood
Abstract:
Abundances of light elements in dwarf stars of different ages are
important constraints for stellar yields, Galactic chemical evolution
and exoplanet chemical composition studies. We have measured C and N
abundances and 12C/13C ratios for a sample of 63 solar twins
spanning a wide range in age, based on spectral synthesis of a
comprehensive list of CH A-X and CN B-X features using HARPS spectra.
The analysis of 55 thin disc solar twins confirms the dependences of
[C/Fe] and [N/Fe] on [Fe/H]. [N/Fe] is investigated as a function of
[Fe/H] and age for the first time for these stars. Our derived
correlation [C/Fe]-age agrees with works for solar-type stars and
solar twins, but the [N/Fe]-age correlation does not. The relations
[C,N/Fe]-[Fe/H] and [C,N/Fe]-age for the solar twins lay under solar.
12C/13C is found correlated with [Fe/H] and seems to have
decreased along the evolution of the local thin disc. Predictions from
chemical evolution models for the solar vicinity corroborate the
relations [C,N/Fe]-[Fe/H], 12C/13C-age, and [N/O]-[O/H], but do
not for the 12C/13C-[Fe/H] and [C/O]-[O/H] relations. The N/O
ratio in the Sun is placed at the high end of the homogeneous
distribution of solar twins, which suggests uniformity in the N-O
budget for the formation of icy planetesimals, watery superearths, and
giant planets. C and N had different nucleosynthetic origins along the
thin disc evolution, as shown by the relations of [C/N], [C/O], and
[N/O] against [O/H] and age. [C/N] and [C/O] are particularly observed
increasing in time for solar twins younger than the Sun.
Description:
The sample is composed of 67 solar twins, stars with atmospheric
parameters very similar to the Sun, within around ±100K in Teff
and ±0.1dex in logg and [Fe/H] (Ramirez, Melendez & Asplund
2009A&A...508L..17R 2009A&A...508L..17R, Cat. J/A+A/508/L17), studied previously by Bedell
et al. (2018ApJ...865...68B 2018ApJ...865...68B, Cat. J/ApJ/865/68), Spina et al.
(2018MNRAS.474.2580S 2018MNRAS.474.2580S, Cat. J/MNRAS/474/2580), and Botelho et al.
(2019MNRAS.482.1690B 2019MNRAS.482.1690B, Cat. J/MNRAS/482/1690). The atmospheric
parameters are those by Spina et al. (2018MNRAS.474.2580S 2018MNRAS.474.2580S, Cat.
J/MNRAS/474/2580).
The spectra were obtained with the HARPS spectrograph (High Accuracy
Radial velocity Planet Searcher) on the 3.6-m telescope of the ESO
(European Southern Observatory) La Silla Observatory in Chile (Mayor
et al. 2003Msngr.114...20M 2003Msngr.114...20M). The HARPS spectra cover
λλ3780-6910Å with a resolving power (R=115000).
Stacking all HARPS spectra of each star resulted in a very high
signal-to-noise ratio (SNR) of approximately 800/pixel as measured
around 6000Å, with a minimum of 300/pixel and a maximum of
1800/pixel. The solar spectrum used in this work is a combination of
several exposures of sunlight reflected from the asteroid Vesta, also
observed with HARPS.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 84 68 Parameters of the 67 solar twins collected from
previous published works
table2.dat 73 14 The comprehensive list of CH A-X lines used in
this work for determining the C abundance in
solar twin stars
table3.dat 73 5 The comprehensive list of CN B-X lines used in
this work for determining the N abundance in
solar twin stars
table4.dat 44 3387 Line lists for the CH A-X line regions after the
gf calibration to the solar spectrum
table5.dat 46 1704 Line lists for the CN B-X line regions after the
gf calibration to the solar spectrum
table6.dat 76 6 The comprehensive list of 13CH-12CH A-X
features used in this work for determining the
12C/13C isotopic ratio in solar twin stars
table7.dat 51 5974 Line lists for the 13CH-12CH A-X feature
regions after the gf calibration to the solar
spectrum
table8.dat 72 64 Carbon and nitrogen abundances and 12C/13C
ratio measured in this work relatively to the
Sun for 63 solar twins
--------------------------------------------------------------------------------
See also:
J/ApJ/865/68 : Abundances for 79 Sun-like stars within 100pc
(Bedell+, 2018)
J/MNRAS/474/2580 : Temporal evolution of neutron-capture elements
(Spina+, 2018)
J/MNRAS/482/1690 : Thorium in solar twins (Botelho+, 2019)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Name Star name
11- 14 I4 K Teff Effective temperature (1)
16 I1 K e_Teff Error on Teff (1)
18- 22 F5.3 [cm/s2] logg Surface gravity (1)
24- 28 F5.3 [cm/s2] e_logg Error on logg (1)
30- 35 F6.3 [-] [Fe/H] Fe/H abundance ratio (1)
37- 41 F5.3 [-] e_[Fe/H] Error on [Fe/H] (1)
43- 46 F4.2 km/s Vmicro Micro-turbulence velocity (2)
48- 51 F4.2 km/s e_Vmicro Error on Vmicro (2)
53- 56 F4.2 km/s Vmacro Macro-turbulence velocity (2)
58- 61 F4.2 km/s Vsini Rotational velocity (2)
63- 66 F4.2 Gyr Age Star age (1)
68- 71 F4.2 Gyr e_Age Error on Age (1)
73- 78 F6.3 [-] [O/H] O/H abundance ratio (3)
80- 84 F5.3 [-] e_[O/H] Error on [O/H] (3)
--------------------------------------------------------------------------------
Note (1): Photospheric parameters and isochrone age are taken from
Spina et al. (2018MNRAS.474.2580S 2018MNRAS.474.2580S, Cat. J/MNRAS/474/2580)
Note (2): Velocities are taken from dos Santos et al. (2016A&A...592A.156D 2016A&A...592A.156D,
Cat. J/A+A/592/A156)
Note (3): The oxygen abundance is taken from Bedell et al. (2018ApJ...865...68B 2018ApJ...865...68B,
Cat. J/ApJ/865/68)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table[23].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 A6 --- Line Line identification (1)
8- 14 F7.2 0.1nm lambda Central wavelength of the spectral absorption
16- 30 A15 0.1nm Sprange Spectral range in which the χ2 is
computed
32- 33 I2 --- Npix Number of pixels
35- 49 A15 0.1nm Bluecont Blue continuum interval
51- 65 A15 0.1nm Redcont Red continuum interval
67- 71 A5 --- Band Vibrational band (arcmin,arcsec)
73 I1 --- Nlines Number of blended lines to form the molecular
absorption
--------------------------------------------------------------------------------
Note (1): The line identification (first column) adopts the short molecule
notation and the wavelength of the main molecular electronic
transition as a whole number in Angstroms
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 A6 --- Line Line identification
8- 16 F9.4 0.1nm lambda Wavelength
18- 22 F5.1 --- Spcode Species code (1)
24- 28 F5.3 eV chi Excitation potential of transition lower level
30- 38 E9.4 --- gf ?=0 Oscillator strength calibrated to the solar
spectrum (2)
40- 44 A5 --- Species Species identification
--------------------------------------------------------------------------------
Note (1): The species code is the MOOG standard notation, i.e. atomic number(s)
before the decimal point (listed in crescent order for molecules)
followed by the ionization level immediately after the decimal point
(0: neutral, 1: first ionized, and so on)
Note (2): Values <10-30 were put to 0.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 A6 --- Line Line identification
8- 16 F9.4 0.1nm lambda Wavelength
18 A1 --- f_lambda [*] Flag on lambda (1)
20- 24 F5.1 --- Spcode Species code (2)
26- 30 F5.3 eV chi Excitation potential of transition lower level
32- 40 E9.4 --- gf ?=0 Oscillator strength calibrated to the solar
spectrum (3)
42- 46 A5 --- Species Species identification
--------------------------------------------------------------------------------
Note (1): Flag as follows:
* = There was an error in the original table and the wavelength was given as
NNNN.24.0 (with NNNN=4179, 4180, 4192, 4193, 4194, 4196, 4212 or 4213),
here we assign the value NNNN.24
Note (2): The species code is the MOOG standard notation, i.e. atomic number(s)
before the decimal point (listed in crescent order for molecules)
followed by the ionization level immediately after the decimal point
(0: neutral, 1: first ionized, and so on)
Note (3): Values <10-30 were put to 0.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Feature Feature name
11- 17 F7.2 0.1nm lambda Central wavelength of the spectral absorption
19- 33 A15 0.1nm Sprange Spectral range in which the χ2 is
computed
35- 36 I2 --- Npix Number of pixels
38- 52 A15 0.1nm Bluecont Blue continuum interval
54- 68 A15 0.1nm Redcont Red continuum interval
70- 74 A5 --- Band Vibrational band (arcmin,arcsec)
76 I1 --- Nlines Number of blended lines to form the molecular
absorption
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table7.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Feature Feature name
11- 19 F9.4 0.1nm lambda Wavelength
21- 29 F9.5 --- Spcode Species code
31- 35 F5.3 eV chi Excitation potential of transition lower level
37- 45 E9.4 --- gf Oscillator strength calibrated to the solar
spectrum
47- 51 A5 --- Species Species identification
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table8.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Name Star name
11- 16 F6.3 [-] [C/H] C/H abundance ratio
18- 22 F5.3 [-] e_[C/H] Error on [C/H]
24- 29 F6.3 [-] [C/Fe] C/Fe abundance ratio
31- 35 F5.3 [-] e_[C/Fe] Error on [C/Fe]
37- 42 F6.3 [-] [N/H] N/H abundance ratio
44- 48 F5.3 [-] e_[N/H] Error on [N/H]
50- 55 F6.3 [-] [N/Fe] N/Fe abundance ratio
57- 61 F5.3 [-] e_[N/Fe] Error on [N/Fe]
63- 67 F5.1 --- C12C13 12C/13C ratio
69- 72 F4.1 --- e_C12C13 Error on C12C13
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 18-Aug-2023