English

Unveiling the Variability and Chemical Composition of AL Col

Solar and Stellar Astrophysics 2025-08-29 v1

Abstract

Using \tess\ short-cadence (120\,s) SAP flux, we identified a rotational frequency of 0.09655\,d1\mathrm{d}^{-1} (Prot=10.35733P_\mathrm{rot}=10.35733\,d). 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 an effective temperature (TeffT_\mathrm{eff}) of {11,750\,K.} %MDPI: Comma added for five digits in the whole text, please check. High-resolution spectroscopic observations covering wavelengthrange 4500--7000\,\AA\ provide refined estimates of \teff\, =\, 13,814\, ±\pm\, 400\,K, \logg\,=\, 4.09\, ±\pm\, 0.08\,dex, and \vsini\, =\, 16 ±\pm 1\,\kms. Abundance analysis shows solar-like composition of O\,\textsc{ii}, Mg\,\textsc{ii}, S\,\textsc{ii}, and Ca\,\textsc{ii}, while helium is under-abundant by 0.62\,dex. Rare earth elements (REEs) exhibit over-abundances of up to 5.2\,dex, classifying the star as an Ap/Bp-type star. AL\,Col has a radius of R=3.74±0.48RR = 3.74\,\pm\,0.48{\rm R_{\odot}}, with its H--R diagram position estimating a mass of M=4.2±0.2MM = 4.2\,\pm\,0.2{\rm M_{\odot}} and an age of 0.12±0.010.12\,\pm\,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.

Keywords

Cite

@article{arxiv.2508.20681,
  title  = {Unveiling the Variability and Chemical Composition of AL Col},
  author = {Surath C. Ghosh and Santosh Joshi and Samrat Ghosh and Athul Dileep and Otto Trust and Mrinmoy Sarkar and Jaime Andrés Rosales Guzmán and Nicolás Esteban Castro-Toledo and Oleg Malkov and Harinder P. Singh and Kefeng Tan and Sarabjeet S. Bedi},
  journal= {arXiv preprint arXiv:2508.20681},
  year   = {2025}
}

Comments

22 pages, 9 figures, published in galaxies journal