Asteroseismic analysis of a young circumstellar disc-hosting A star HD 110058

www.postersession.com www.postersession.com www.postersession.com Asteroseismic analysis of a young circumstellar disc-hosting A star Muhammad Fajrin1, Michael Elston1, Karen Pollard1, Emily Brunsden2, Daniel Holdsworth2,3 1University of Canterbury, Christchurch, New Zealand, 2University of York, York, UK 3South African Astronomical Observatory, South Africa CONCLUSIONS References INTRODUCTION PULSATION PROPERTIES Young stars hosting circumstellar discs are important astrophysical targets for studying the processes and mechanisms of star and planetary system formation. We are interested in studying young stellar systems, particularly ones that show indications of star–disc interactions, and we would like to explore and utilise asteroseismology to better constrain their nature. •HD 110058 is a young A0 star with a warped circumstellar disk similar to that of β Pictoris, located in the Lower Centaurus-Crux subgroup of the Sco-Cen OB association (e.g. Pecaut & Mamajek 2016). •Previous studies reported a low metallicity for the star, with the accretion of metal-poor material suggested as a possible explanation (Rebollido et al., 2020; Borthakur et al., 2025). •The scenario may be indicative of “falling evaporating bodies” (FEBs), a phenomenon linked to the infall of volatile-rich exocomets, similar to that observed in the β Pictoris system (e.g. Beust et al., 1991). HD 110058 has been observed by TESS in Sectors 10, 11, 37, and 64. For this study, we used the TESS 2-minute cadence PDCSAP light curves from Sectors 10 and 11, obtained via the SPOC pipeline. We processed the light curves using the Pyriod package (Bell, 2020) to identify oscillation frequencies and perform pre-whitening. STELLAR MODELING •We detected up to 100 frequencies, all consistent with δ Scuti-type variability, and noted a regular frequency spacing (Figure 1). •Using the echelle Python package (Hey & Ball 2020), we found a large frequency spacing (Δν) of 7.35 c/d. •From the échelle diagram, we successfully identified ridges corresponding to spherical degree modes ℓ = 0 and ℓ = 1. •We generated a grid of stellar evolution models for a pre-main sequence, non-rotating star using MESA (version 24.08.01; Paxton et al., 2019). The corresponding theoretical pulsation frequencies were computed using GYRE (Townsend & Teitler, 2013). •The best-fit models were determined by minimizing the reduced χ² between observed and modeled frequencies, with additional constraints from spectroscopy following the approach described in Steindl et al. (2022). •We performed model fitting using stellar parameters reported in Borthakur et al. (2025), where Teff = 7880 ± 80 K and log g 4.00 ± 0.05. However, we decided to adopt a 3σ uncertainty range. •Using MESA+GYRE, we successfully identified radial orders in the range of n = 4–7 for ℓ = 0 and ℓ = 1 (Figure 2). •The best-fitting model is shown in Figure 3. Assuming σf = 0.1 c/d, •we obtained a stellar mass of 1.53 ± 0.15 M☉ and an age of 12.24 ± 0.30 Myr. •The age estimate is younger than previously estimated for LCC, but they remain within the age spread. •We also constrained the bulk metallicity of Z = 0.010 ± 0.002. The low metallicity is consistent with the classification of HD 110058 as a λ Boo star, potentially due to metal-poor accretion from infalling exocomet materials. Bell K. 2022. Pyriod: Period detection and fitting routines Beust H, Vidal-Madjar A, Ferlet R. 1991. A&A. 247:505 Borthakur SPD, Kama M, Fossati L, Kral Q, Folsom CP, et al. 2025. A&A. 697:A59 Hey D, Ball W. 2020. Echelle: Dynamic echelle diagrams for asteroseismology Paxton B, Smolec R, Schwab J, Gautschy A, Bildsten L, et al. 2019. ApJ. Suppl. Ser. 243(1):10 Pecaut MJ, Mamajek EE. 2016. MNRAS. 461(1):794–815 Rebollido I, Eiroa C, Montesinos B, Maldonado J, Villaver E, et al. 2020. A&A. 639:A11 Steindl T, Zwintz K, Müllner M. 2022. A&A. 664:A32 Townsend RHD, Teitler SA. 2013. MNRAS. 435(4):3406–18 Background image credit: ESO/L. Calçada Figure 3. Kiel diagram of the best fitted model The solid line shows the stellar evolutionary track for a model of mass 1.53 M☉ and Z = 0.010. The open circle indicates the location of the best-fitting model to the observed parameters. Figure 2. Echelle diagram Echelle diagram showing v mod Δν = 7.35 c/d. Plotted model frequencies start from n = 1. Figure 1. HD 110058 photometric variability Top: Light curve showing relative flux variations with a fitted model (red). Bottom: Amplitude spectrum showing significant pulsation frequencies in the δ Scuti range and corresponding mode ℓ = 0 (red) and ℓ = 1 (blue).