J/MNRAS/500/54 Asteroseismic modelling of solar-type stars (Nsamba+, 2021)
Asteroseismic modelling of solar-type stars: a deeper look at the treatment of
initial helium abundance.
Nsamba B., Moedas N., Campante T.L., Cunha M.S., Garcia Hernandez A.,
Suarez J.C., Monteiro M.J.P.F.G., Fernandes J., Jiang C., Akinsanmi B.
<Mon. Not. R. Astron. Soc., 500, 54-65 (2021)>
=2021MNRAS.500...54N 2021MNRAS.500...54N (SIMBAD/NED BibCode)
ADC_Keywords: Asteroseismology ; Stars, fundamental ; Effective temperatures ;
Abundances, [Fe/H] ; Stars, diameters ; Stars, masses ;
Stars, ages ; Abundances, peculiar ; Models
Keywords: asteroseismology - stars: evolution - stars: fundamental parameters -
stars: oscillations - stars: statistics
Abstract:
Detailed understanding of stellar physics is essential towards a
robust determination of stellar properties (e.g. radius, mass, and
age). Among the vital input physics used in the modelling of
solar-type stars which remain poorly constrained, is the initial
helium abundance. To this end, when constructing stellar model grids,
the initial helium abundance is estimated either (i) by using the
semi-empirical helium-to-heavy element enrichment ratio,
(ΔY/ΔZ), anchored to the standard big bang nucleosynthesis
value, or (ii) by setting the initial helium abundance as a free
variable. Adopting 35 low-mass, solar-type stars with multiyear Kepler
photometry from the asteroseismic 'LEGACY' sample, we explore the
systematic uncertainties on the inferred stellar parameters (i.e.
radius, mass, and age) arising from the treatment of the initial
helium abundance in stellar model grids. The stellar masses and radii
derived from grids with free initial helium abundance are lower
compared to those from grids based on a fixed ΔY/ΔZ ratio.
We find the systematic uncertainties on mean density, radius, mass,
and age arising from grids which employ a fixed value of
ΔY/ΔZ and those with free initial helium abundance to be
∼0.9 per cent, ∼2 per cent, ∼5 per cent, and ∼29 per cent,
respectively. We report that the systematic uncertainties on the
inferred masses and radii arising from the treatment of initial helium
abundance in stellar grids lie within the expected accuracy limits of
ESA's PLATO, although this is not the case for the age.
Description:
The Kepler LEGACY sample stars employed in this study consists of 35
low-mass solar-type stars with at least 12 months observation of short
cadence data (Δt=58.89s). The seismic data of these stars are
available in Lund et al. (2017ApJ...835..172L 2017ApJ...835..172L, Cat. J/ApJ/835/172). It
is worth noting that for each star, we only adopted oscillation modes
whose probability of detection is reported to be at least 'strong' by
Lund et al. (2017ApJ...835..172L 2017ApJ...835..172L, Cat. J/ApJ/835/172). Table 1 shows
the values of spectroscopic parameters, that is, metallicity, [Fe/H],
and effective temperatures, Teff, for each star in our sample. Our
stellar sample also includes the asteroseismic binary HD 176465 (White
et al. 2017A&A...601A..82W 2017A&A...601A..82W; Nsamba et al. 2017EPJWC.16005010N 2017EPJWC.16005010N) and the
Sun.
We constructed three stellar grids (namely; A, B, and C) varying only
in the treatment of the initial helium mass fraction (Yi), using
MESA version 9793. The evolutionary tracks were evolved from the
pre-main sequence (PMS) and stellar models were stored starting from
the zero-age main-sequence (ZAMS) which we defined as the region along
the evolutionary tracks where the model nuclear luminosity is
approximately 99 per cent of its total luminosity.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 53 32 Global asteroseismic and spectroscopic
parameters of our stellar sample
grida.dat 495 34 Stellar properties for our sample derived from
grid A
gridb.dat 495 34 Stellar properties for our sample derived from
grid B
gridc.dat 495 34 Stellar properties for our sample derived from
grid C
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- Name KIC identifier
13- 19 F7.3 uHz Dnu Average large frequency separation from Lund et
al. (2017ApJ...835..172L 2017ApJ...835..172L, Cat. J/ApJ/835/172)
21- 25 F5.3 uHz E_Dnu Upper error on Dnu
27- 31 F5.3 uHz e_Dnu Lower error on Dnu
33- 36 I4 K Teff Effective temperature
38- 40 I3 K e_Teff Error on Teff
42- 46 F5.2 [-] [Fe/H] Fe/H abundance ratio
48- 51 F4.2 [-] e_[Fe/H] Error on [Fe/H]
53 I1 --- Ref Reference for the spectroscopic parameters (1)
--------------------------------------------------------------------------------
Note (1): Reference as follows:
1 = Buchhave & Latham (2015ApJ...808..187B 2015ApJ...808..187B, Cat. J/ApJ/808/187)
2 = Casagrande et al. (2014ApJ...787..110C 2014ApJ...787..110C, Cat. J/ApJ/787/110)
3 = Pinsonneault et al. (2012ApJS..199...30P 2012ApJS..199...30P, Cat. J/ApJS/199/30)
4 = Pinsonneault et al. (2014ApJS..215...19P 2014ApJS..215...19P, Cat. J/ApJS/215/19)
5 = Ramirez, Melendez & Asplund (2009A&A...508L..17R 2009A&A...508L..17R, Cat. J/A+A/508/L17)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: grid[abc].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- Name KIC identifier (except for HD176465A and
HD176465B)
13- 33 E21.16 Msun Mass Star mass
35- 55 E21.16 Msun e_Mass Error on Mass
57- 77 E21.16 Rsun Rad Star radius
79- 99 E21.16 Rsun e_Rad Error on Rad
101- 121 E21.16 [cm/s2] logg Surface gravity
123- 143 E21.16 [cm/s2] e_logg Error on logg
145- 165 E21.16 Myr Age Star age
167- 187 E21.16 Myr e_Age Error on Age
189- 209 E21.16 Lsun Lum Star luminosity
211- 231 E21.16 Lsun e_Lum Error on Lum
233- 253 E21.16 g/cm3 rho Star density
255- 275 E21.16 g/cm3 e_rho Error on rho
277- 297 E21.16 --- Xi Fractional initial hydrogen abundance
299- 319 E21.16 --- e_Xi Error on Xi
321- 341 E21.16 --- Yi Fractional initial helium abundance
343- 363 E21.16 --- e_Yi Error on Yi
365- 385 E21.16 --- Xs Fractional surface hydrogen abundance
387- 407 E21.16 --- e_Xs Error on Xs
409- 429 E21.16 --- Ys Fractional surface helium abundance
431- 451 E21.16 --- e_Ys Error on Ys
453- 473 E21.16 --- amlt Mixing length parameter
475- 495 E21.16 --- e_amlt Error on amlt
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 15-Sep-2023