Modeling magnetically active solar-like stars observed by TESS

References Modeling Magnetically active solar-like stars observed by Tess Nuno Moedas1; Raffaele Reda2,1; Maria Pia Di Mauro1; Luca Giovannelli2,1 1 - Istituto Nazionale di Astrofisica (INAF/IAPS Roma) 2–Dipartimento di Fisica, Università degli Studi di Roma “Tor Vergata”, Roma, Italy Introduction Understanding the magnetic activity in stars is important; it influences stellar structure and evolution, and it interacts with the hosted planets, affecting their formation and evolution. However, to better understand the magnetic interaction in the stellar system, it is important to have an accurate determination of the fundamental stellar properties. In this work, we model a sample of solar-like stars for which magnetic activity data are also available. Using the recent asteroseismic data obtained by TESS, we infer their fundamental properties using a grid of stellar models computed by the MESA stellar evolution code, taking into account the effects of chemical transport mechanisms. This allow us to study how stellar parameters correlates with magnetic activity and in the future will permit us to understand how magnetic activity interacts with stellar oscillations, as well as to study the star-planet interactions. a–García Pérez et al. (2021);b –Perdelwitz et al. (2024); c –Abdurrof’uf et al. (2012); d –Di Mauro et al. (submitted); e –Da Silva et al. (2015); f –Corsaro et al. (2024); g –Present workcbased on Mount Wilson data. Observed parameters for magnetic active solar-like stars Star 𝑻𝐞𝐟𝐟 (K) 𝐅𝐞/𝐇 (dex) 𝐥𝐨𝐠(𝒈) (dex) 𝜟𝝂 (μHz)f𝝂𝒎𝒂𝒙 (μHz)fS-indexg HD3795 5358 ±50a-0.36±0.05a3.71 ± 0.10a48.34 ± 4.67 815−10 +9 0.155±0.003 HD23249 5145 ± 50b0.14 ± 0.04b3.72 ± 0.10b40.63 ± 2.52 676−5 +5 0.136±0.003 HD35296 6132 ± 50a−0.3 ± 0.05a4.29 ± 0.10a97.07 ± 3.75 1911−27 +25 0.301±0.012 HD68290 5173 ± 140c0.10 ± 0.05c3.297 ± 0.40c10.17 ± 0.18 105−2 +2 0.328±0.014 HD81809 5640 ± 150d−0.57 ± 0.14d3.52 ± 0.77d46.52 ± 1.68 716−12 +11 0.171±0.005 HD88737 6061 ± 50a−0.06 ± 0.05a3.78 ± 0.10a34.1 ± 1.23 668−18 +20 0.236±0.009 HD117176 5600 ± 50e−0.02 ± 0.05e4.05 ± 0.15e52.22 ± 2.71 946−17 +13 0.142±0.002 HD142373 5859 ± 50e−0.44 ± 0.05e4.12 ± 0.21e58.35 ± 2.88 1036−13 +17 0.146±0.002 HD187691 6129 ± 50e0.13 ± 0.05e4.18 ± 0.20e84.51 ± 6.07 1827−38 +27 0.148±0.003 HD188512 5197 ± 50b−0.16 ±0.04b3.69 ± 0.10b26.82 ± 1.87 418−4 +3 0.136±0.003 HD219834A 5531 ± 50b0.16 ± 0.05b3.97 ± 0.10b50.82 ± 2.64 816−20 +14 0.154±0.006 Modeling Results Star Stage 𝑴 𝐌⊙𝑹 𝐑⊙𝑳 𝐋⊙ Age (Gyr) 𝑿𝒄𝒀𝒊𝒁𝒊𝒀𝒔𝒁𝒔𝝉𝒄𝒛 (days) HD3795 SG 0.84±0.07 1.82±0.08 2.47±0.24 12.7 ± 1.8 0.0 0.289 ± 0.024 0.0065 ± 0.0007 0.261 ± 0.024 0.0060 ± 0.0007 84 HD23249 SG 1.19±0.12 2.39±0.12 3.61±0.39 5.5±1.1 0.0 0.299 ± 0.025 0.0178 ± 0.0019 0.288 ± 0.025 0.0173 ± 0.0019 102 HD35296 MS 0.93±0.07 1.21±0.04 1.86±0.15 7.6±1.0 0.004±0.004 0.287 ± 0.025 0.0079 ± 0.0009 0.248 ± 0.025 0.0070 ± 0.0008 37 HD68290 RGB 1.03±0.08 5.74±0.18 14.87±1.3 7.3±2.1 0.0 0.323 ± 0.014 0.0138 ± 0.0016 0.334 ± 0.014 0.0137 ± 0.0016 189 HD81809 SG 1.01±0.06 2.06±0.06 4.46±0.29 6.5±0.3 0.0 0.281 ± 0.026 0.0057 ± 0.0016 0.245 ± 0.023 0.0052 ± 0.0016 57 HD88737 SG 1.46±0.06 2.66±0.07 8.60±0.54 2.9±0.1 0.0 0.261 ± 0.017 0.0152 ± 0.0018 0.211 ± 0.017 0.0131 ± 0.0015 34 HD117176 SG 1.07±0.08 1.88±0.07 3.15±0.27 7.7±0.7 0.0 0.283 ± 0.026 0.0141 ± 0.0017 0.252 ± 0.016 0.0133 ± 0.0015 62 HD142373 SG 0.91±0.06 1.64±0.05 2.87±0.23 9.7±0.8 0.0 0.280 ± 0.025 0.0060 ± 0.0007 0.240 ± 0.025 0.0053 ± 0.0006 52 HD187691 MS 1.20±0.08 1.41±0.05 2.52±0.21 3.7±0.6 0.218±0.076 0.287 ± 0.026 0.0202 ± 0.0025 0.250 ± 0.026 0.0183 ± 0.0022 34 HD188512 RGB 1.27±0.15 3.14±0.18 6.47±0.83 3.4±1.1 0.0 0.293 ± 0.026 0.0089 ± 0.0009 0.289 ± 0.026 0.0088 ± 0.0009 113 HD219834A SG 1.16±0.09 2.10±0.08 3.74±0.33 5.8±0.5 0.0 0.302 ± 0.027 0.0196 ± 0.0023 0.276 ± 0.026 0.0184 ± 0.0022 66 Including: ●Gravitational settling 𝑔set ; ●Radiative accelerations 𝒈𝐫𝐚𝐝 computed with the SingleValued Parameters (SVP, LeBlanc & Alecian 2004; Alecian & LeBlanc 2020) method; ●Turbulent Mixing 𝐷turb calibrated to reproduce the helium abundance in F-type stars (Verma & Silva Aguirre, 2019). Target Sample Main Inputs: -Asplund et al. (2009) solar chemical mixture -OPAL EOS -OPAL opacity tables -Nacre Nuclear reactions -Cox & Giuli (1935) mixing length prescription We used a grid of stellar models from Moedas et al. (2024) that was computed using the MESA r12778 evolution code (Paxton et al.2019). •The results show that the majority of the targets sample is in the SG stage of evolution, two stars are in the MS, and two are in RGB stars. •From these results we do not see clear correlation of S-index with mass, radius and age. •We confirm that the magnetic activity appears to decrease as the star is more evolved. •Our models show that HD688290 is in the RGB stage, characterized by a very high Sindex not expected for evolved stars. However, it is the only star for which the models are not able to fit the 𝑇eff. •Except for the outlier the magnetic activity decreases as the convective region become deeper and the 𝜏𝐶𝑍 grow longer •Except for three stars in the sample (HD35296,HD688290, HD88737), the average Sindex is compatible with the solar one or even lower, confirming that oscillations are easier to be detected in presence of low magnetic index. •A more in-depth multivariant analysis is needed to address any dependence of the Sindex on stellar properties. Fig 2: Kiel (left panel) and Δ𝜈 − 𝑇eff (right panel) diagram of the evolutionary track of the best models. The star points shows the observation values, and the circles the best fitted models. MS SG RGB Fig 3: Estimated average S-index as function of the different inferred stellar properties. In the upper panels we see the stellar mass, stellar radius and stellar age. In the lower panels we show the dimensionless age (we defined 0 to 1MS,1to 2 SG, and 2 to 3 RGB), the convective turnover time and the size of convective zone. Fig 1: Upper panel: Example of S-index variations for one of the targets of the selected sample (HD81809). The blue are measurement from Mount Wilson Observatory (Wilson 1968,1978) and orange are from Lowell telescope (Hall & Lockwood 1995). Lower panel shows the Lomb-Scargle periodograms. (Di Mauro et al. submitted) MS –Main Sequence; SG –Sub-Giant; RGB –Red Giant Branch 𝜏𝐶𝑍 =𝑑𝑐𝑧 ҧ𝑣𝐶 Thickness of convective Zone Average convective velocity Convective turnover Time Abdurro’uf et al. 2022, ApJS, 259, 35 Alecian & LeBlanc 2020, MNRAS, 498, 3420 Asplund et al. 2019, A&A, 47, 481 Corsaro et al. 2024, A&A, 683, 9 Cox & Giuli 1968 Da Silva et al 2015, A&A, 580, 18 García Pérez et al. 2021, MNRAS, 505, 3 Hall & Lockwood 1995, ApJ, 438, 404 Results Stellar Models LeBlanc & Alecian 2004, MNRAS, 418, 195 Moedas et al. 2024, A&A, 695,12 Paxton et al. 2019, ApJS, 243, 10 Perdelwitz et al 2024, A&A, 683, 6 Verma & Silva Aguirre 2019, MNRAS, 489, 1850 Wilson 1968, ApJ, 153, 221 Wilson 1978, ApJ, 226, 379 outlier outlier