Unveiling the Variability and Chemical Composition of ALCol

Abstract

In this study, we present analysis of TESS photometry, spectral energy distribution (SED), high-resolution spectroscopy, and spot modeling of the α2 CVn-type star ALCol (HD46462). The primary objective is to determine its fundamental physical parameters and investigate its surface activity characteristics. Using TESS short-cadence (120s) SAP flux, we identified a rotational frequency of 0.09655d−1 (Prot = 10.35733d). Wavelet analysis reveals that while the amplitudes of the harmonic components vary over time, the strength of the primary rotational frequency remains stable. A SED analysis of multi-band photometric data yields Academic Editor: MargoAller Received: 17June2025 Revised: 1August2025 Accepted: 5August2025 Published: 14 August2025 Citation: Ghosh, S.C.;Joshi, S.; Ghosh,S.; Dileep, A.; Trust, O.; Sarkar, M.; Rosales Guzmán,J.A.; Castro-Toledo, N.E.; Malkov, O.; Singh, H.P.; et al. Unveiling the Variability and Chemical Composition of ALCol. Galaxies 2025, 13, 93. https:// doi.org/10.3390/galaxies13040093 Copyright: ©2025bytheauthors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/ licenses/by/4.0/). an effective temperature (Teff) of 11,750K. High-resolution spectroscopic observations covering wave length range 4500–7000Å provide refined estimates of Teff = 13,814 ± 400K, log g= 4.09 ± 0.08dex, and υsini = 16 ± 1kms−1. Abundance analysis shows solar-like composition of OII, MgII, SII, and CaII, while helium is under-abundant by 0.62dex. Rare earth elements (REEs) exhibit over-abundances of up to 5.2dex, classifying the star as an Ap/Bp-type star. ALCol has a radius of R = 3.74 ± 0.48R⊙, with its H–R diagram position estimating a mass of M = 4.2 ± 0.2M⊙ and an age of 0.12 ± 0.01 Gyr, indicating that the star has slightly evolved from the main sequence. The TESS light curves were modeled using a three-evolving-spot configuration, suggesting the presence of differential rotation. This star is a promising candidate for future investigations of magnetic field diagnostics and the vertical stratification of chemical elements in its atmosphere.