Studying the surface effect in Procyon A as an F-type star

Abstract

Procyon A is an F-type main-sequence star in a binary system. It has been the subject of numerous ground-based and space-based observing campaigns, providing precise classical constraints, including a well-determined mass. It was also among the first stars in which individual frequencies were detected, making it a crucial benchmark for F-type stars. Our goal is to investigate the surface effect, namely the discrepancy between observed and model oscillation frequencies due to inadequate modeling of the surface stellar layers, especially important in F-type stars. Using Procyon A as a case study, we aim to understand how different surface correction prescriptions impact the inference of the fundamental properties of this star, and compare the results with those obtained when the surface corrections are neglected. We inferred the fundamental stellar properties employing a grid of models computed with MESA, including gravitational settling, radiative accelerations, and turbulent mixing. We selected the best-fit models using the AIMS code taking into account different methods to fit the individual frequencies. We find that the use of surface corrections can introduce uncertainties up to 7\% in the inferred stellar mass. We identify that the most reliable stellar mass estimates are obtained when using frequency ratios, the Sonoi et al. (2015) surface correction or directly fitting the individual frequencies. Our results indicate that the surface effects in F-type stars differ from those found in the Sun and in solar-like stars, highlighting the need to be careful when considering the surface corrections for these stars.

Figures (8)

• Figure 1: Kiel diagram showing some computed evolutionary tracks with metallicity $\rm{[M/H]}_i=0.0$ and $Y_i=0.26$ (solar composition) in solid gray lines. The star symbol shows the Procyon A's location in the diagram. The blue solid line is the evolutionary track of the best model (circle symbol) from the $r_{02}$ test considering radius in the inference of Scenario A.
• Figure 2: Relative difference between the inferred and reference values (subscript $r$) obtained in test 1 for the two sets of frequencies (Scenario A and B). Top left panel shows the surface gravity, top right panel the surface radius, bottom left panel the surface luminosity, and bottom right panel the stellar mass. The dotted line indicate where the relative difference is 0.
• Figure 3: Same plots as Fig. \ref{['fig:diff_set_all']}, but showing the relative differences obtained in test 2.
• Figure 4: Same plots as Fig. \ref{['fig:diff_set_all']}, but showing the relative differences obtained in test 3.
• Figure 5: $r_{02}$ ratios of test 2 for Scenario A (top panel) and Scenario B (bottom panel). The black points with error bars are computed from the observed frequencies and green points for the best-fit model.