Advanced asteroseismic modelling: breaking the degeneracy between stellar mass and initial helium abundance
arXiv:2207.00235 · doi:10.1093/mnras/stac1860
Abstract
Current stellar model predictions of adiabatic oscillation frequencies differ significantly from the corresponding observed frequencies due to the non-adiabatic and poorly understood near-surface layers of stars. However, certain combinations of frequencies -- known as frequency ratios -- are largely unaffected by the uncertain physical processes as they are mostly sensitive to the stellar core. Furthermore, the seismic signature of helium ionization provides envelope properties while being almost independent of the outermost layers. We have developed an advanced stellar modelling approach in which we complement frequency ratios with parameters of the helium ionization zone while taking into account all possible correlations to put the most stringent constraints on the stellar internal structure. We have tested the method using the Kepler benchmark star 16 Cyg A and have investigated the potential of the helium glitch parameters to constrain the basic stellar properties in detail. It has been explicitly shown that the initial helium abundance and mixing-length parameters are well constrained within our framework, reducing systematic uncertainties on stellar mass and age arising for instance from the well-known anti-correlation between the mass and initial helium abundance. The modelling of six additional Kepler stars including 16 Cyg B reinforces the above findings and also confirms that our approach is mostly independent from model uncertainties associated with the near-surface layers. Our method is relatively computationally expensive, however, it provides stellar masses, radii and ages precisely in an automated manner, paving the way for analysing numerous stars observed in the future during the ESA PLATO mission.
18 pages, 14 figures (including 5 in the appendix), 3 tables, MNRAS in press
References in corpus (17)
- The K2 Mission: Characterization and Early results
- ADIPLS -- the Aarhus adiabatic oscillation package
- Correcting stellar oscillation frequencies for near-surface effects
- Standing on the shoulders of Dwarfs: the Kepler asteroseismic LEGACY sample II - radii, masses, and ages
- Standing on the shoulders of Dwarfs: the asteroseismic LEGACY sample I - oscillation mode parameters
- A new correction of stellar oscillation frequencies for near-surface effects
- Asteroseismology of the solar analogs 16 Cyg A & B from Kepler observations
- Asteroseismology for "à la carte" stellar age-dating and weighing: Age and mass of the CoRoT exoplanet host HD 52265
- An asteroseismic signature of helium ionization
- A Stellar Model-fitting Pipeline for Asteroseismic Data from the Kepler Mission
- Asteroseismic estimate of helium abundance of a solar analog binary system
- Seismic measurement of the locations of the base of convection zone and helium ionization zone for stars in the {\it Kepler} seismic LEGACY sample
- Prospects for asteroseismic inference on the envelope helium abundance in red giant stars
- Model-independent measurement of internal stellar structure in 16 Cygni A and B
- A Theoretical Study of Acoustic Glitches in Low-Mass Main-Sequence Stars
- Anomalies in the Kepler Asteroseismic Legacy Project Data. A re-analysis of 16 Cyg A&B, KIC8379927 and 6 solar-like stars
- Comprehensive stellar seismic analysis : New method exploiting the glitches information in solar-like pulsators