J/MNRAS/482/1690 Thorium in solar twins (Botelho+, 2019)
Thorium in solar twins: implications for habitability in rocky planets.
Botelho R.B., Milone A. de C., Melendez J., Bedell M., Spina L.,
Asplund M., dos Santos L., Bean J.L., Ramirez I., Yong D., Dreizler S.,
Alves-Brito A., Yana Galarza J.
<Mon. Not. R. Astron. Soc., 482, 1690-1700 (2019)>
=2019MNRAS.482.1690B 2019MNRAS.482.1690B (SIMBAD/NED BibCode)
ADC_Keywords: Abundances ; Stars, fundamental ; Stars, double and multiple ;
Exoplanets ; Optical
Keywords: stars: abundances - stars: fundamental parameters -
stars: solar-type - Galaxy: disc -
solar neighbourhood; planets and satellites: terrestrial planets
Abstract:
We have investigated the thorium (Th) abundance in a sample of 53 thin
disc solar twins covering a wide range of ages. These data provide
constrains on the mantle energy budget of terrestrial planets that can
be formed over the evolution of the Galaxy's thin disc. We have
estimated Th abundances with an average precision of 0.025dex (in both
[Th/H] and [Th/Fe]) through comprehensive spectral synthesis of a ThII
line present at 4019.1290Å, using very high resolution (R=115000)
high quality HARPS spectra obtained at the ESO La Silla Observatory.
We have confirmed that there is a large energy budget from Th decay
for maintaining mantle convection inside potential rocky planets
around solar twins, from the Galactic thin disc formation until now,
because the pristine [Th/H]ZAMS is super-solar on average under a
uniform dispersion of 0.056dex (varying from +0.037 up to +0.138dex
based on linear fits against isochrone stellar age). Comparing to
neodymium (Nd) and europium (Eu), two others neutron-capture elements,
the stellar pristine abundance of Th follows Eu along the Galactic
thin disc evolution, but it does not follow Nd, probably because
neodymium has a significant contribution from the s-process (about 60
per cent).
Description:
The sample is composed of 67 solar twins (stars with effective
temperature, surface gravity, and metallicity around the solar values
within ±100K in Teff and within ±0.1dex in logg and [Fe/H]),
which were recently analysed by Spina et al. (2018MNRAS.474.2580S 2018MNRAS.474.2580S) and
Bedell et al. (2018ApJ...865...68B 2018ApJ...865...68B).
Spina et al. (2018MNRAS.474.2580S 2018MNRAS.474.2580S) derived their photospheric
parameters by applying a line-by-line differential spectroscopic
analysis relative to the Sun through equivalent width (EW)
measurements of FeI and FeII lines. The estimated typical errors in
Teff, logg, [Fe/H], and ξ (micro-turbulence velocity) are,
respectively, 4K, 0.012, 0.004dex and 0.011km/s.
High Accuracy Radial velocity Planet Searcher (HARPS) spectra are used
in this work to extract Th abundances. HARPS is an ultra-stable
echelle spectrograph installed on the 3.6m telescope of the European
Southern Observatory (ESO) at La Silla Observatory in Chile (Mayor et
al. 2003Msngr.114...20M 2003Msngr.114...20M). The HARPS spectra covers
λ=3780-6910Å under a resolving power R=115000. Each
one-dimensional spectrum comes from more than 50 stacked spectra that
are previously Doppler-corrected and carefully continuum normalized.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 111 59 Stellar parameters of the sample stars collected
from previous published works (covering 58 solar
twins)
table2.dat 40 151 Line list after the gf calibration to the solar
spectrum
table3.dat 49 68 Thorium abundance measured in this work
relatively to the Sun for 67 solar twins
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Name Star ID (HIP NNNNNN)
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] Iron to Hydrogen 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 (1)
48- 51 F4.2 km/s e_Vmicro Error on Vmicro (1)
53- 56 F4.2 km/s Vmacro Macro-turbulence velocity (2)
58- 61 F4.2 km/s Vsini Line-of-sight rotational velocity (2)
63- 66 F4.2 Gyr Age Isochrone stellar age (1)
68- 71 F4.2 Gyr e_Age Error on Age (1)
73- 78 F6.3 --- [Si/H] Silicon to Hydrogen abundance ratio (3)
80- 84 F5.3 --- e_[Si/H] Error on [Si/H] (3)
86- 91 F6.3 --- [Nd/H] Neodymium to Hydrogen abundance ratio (3)
93- 97 F5.3 --- e_[Nd/H] Error on [Nd/H] (3)
99-104 F6.3 --- [Eu/H] Europium to Hydrogen abundance ratio (3)
106-111 F6.4 --- e_[Eu/H] Error on [Eu/H] (3)
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Note (1): Photospheric parameters and isochrone age from
Spina et al. 2018MNRAS.474.2580S 2018MNRAS.474.2580S
Note (2): Macro-turbulence and rotation velocities from
dos Santos et al. 2016A&A...592A.156D 2016A&A...592A.156D
Note (3): Elemental abundances from Bedell et al. 2018ApJ...865...68B 2018ApJ...865...68B
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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 F9.4 0.1nm lambda Wavelenght (1)
11- 19 F9.5 --- spcode Species code (2)
21- 25 F5.3 eV Xe Excitation potential of transition inferior
level
27- 35 E9.7 --- gf Log of the oscillator strength (3)
37- 40 A4 --- spid Species identification
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Note (1): The list covers 2Å around the Fe-Ni-Mn-Th-Co-CN-Ce-CH blend at
4019Å
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) and also by mass numbers
for molecules in the case of isotopic species discriminated (listed
in crescent order)
Note (3): gf values calibrated for reproducing the line profiles, adopting a
solar spectrum obtained with the same instrument and resolution.
We have performed the calibration of gf-values of all lines in the
region λ=4000-4030Å through an automatic procedure under a
line-by-line basis, using the flux at the core of each individual
line.
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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- 9 A9 --- Name Star ID (HIP NNNNNN)
11- 16 F6.3 --- [Th/H] Thorium to Hydrogen abundance
18- 22 F5.3 --- e_[Th/H] Error on [Th/H]
24- 29 F6.3 --- [Th/Fe] Thorium to Iron abundance
31- 35 F5.3 --- e_[Th/Fe] Error on [Th/Fe]
37- 39 I3 --- SNR Signal to noise ratio
41- 49 F9.5 --- Chi2min Minimized chi-squared (1)
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Note (1): A polynomial fit is applied for Chi2 as a function of [Th/Fe] to
search for the minimum value and the resulting Th abundance ratio
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 29-Jun-2022