2025/05/12 by Y. Wang, Yuetong Wang, Guifang Lin +3
Physics and Astronomy · #Stellar, planetary, and galactic studies #Gamma-ray bursts and supernovae #Astrophysics and Star Formation Studies
paper · pdf · doi:10.3847/1538-4357/adc71a
Abstract Recent convincing evidence is found within asteroseismology that suggests the magnetic fields exist in three red giants. Research on small-scale magnetic fields in the Sun and HD 49385 has shown that they have a certain corrective effect on the systematic discrepancies between observed and theoretical frequencies. Here we apply a similar method applied for the Sun to a red giant, KIC 9145955, to explore the impact of small-scale magnetic fields in the photosphere on its frequencies. We find that the calculated frequencies of our best-fit model, which simulates the effect of the magnetic fields by artificially modifying the Eddington T − τ relation, perfectly match those of the observed l = 0, 1, and 2 modes, indicating the existence of small-scale magnetic fields with an upper strength limit of 65 G and concentrating at a height 13,100 km in the photosphere. Based on the best-fit model, we revise the stellar parameters of KIC 9145955 as M = 1.23 ± 0.04 M ⊙ , R = 5.57 ± 0.06 R ⊙ , L = 19.85 ± 0.5 L ⊙ , Age = 3.83 ± 0.5 Gyr, M He = 0.2108 ± 0.0005 M ⊙ , and R He = 0.0306 ± 0.0001 R ⊙ .