A comprehensive reanalysis of HD 99458. Not a magnetic Ap star but an oscillating Algol with ongoing mass transfer
Year: 2026
Type: article
Abstract: Since 2019, has been known as a unique example of a δ,Sct variable with chemical peculiarities of Ap type in an eclipsing binary. HD,99458 We aim to review the peculiar status of the star with new observational materials. The current study is the result of meticulous analysis of space-based photometry from Kepler K2 and TESS, multi-site spectroscopic and spectropolarimetric observations, as well as speckle-interferometric data. Asteroseismic modelling of stellar pulsation is an essential part of the research. We find to be an eclipsing Algol-type system with active mass transfer from the cool companion filling its Roche lobe to the pulsating primary. We identified signatures of a disc and accretion with varying rates in spectra and light curves. The system's orbital period increases with the rate dot HD,99458 P _ orb -1 $, indicating potential multiplicity. We failed to detect traces of the primary's magnetic field or excessive abundances, both of which are necessary to classify as an Ap star. We have constrained the fundamental parameters of the pulsating primary and analysed its pulsation using asteroseismology. In space-based photometry, we identified pulsation modes with angular degree ellłeq3. Two-dimensional Fourier analysis of spectroscopic time series reveals pulsations in the form of standing waves with the azimuthal orders $|m|=5 as a triaxial gravitationally distorted pulsator. HD,99458 Combined analysis of photometry and spectroscopy confirms the status of HD,99458 Our comprehensive study affirms the new classification for . HD,99458
Source: Astronomy and Astrophysics
Authors: E. Semenko, Z. Mikulášek, D. Mkrtichian, P. Walczak, M. Gabdeev, J. Janík, O. Kochukhov, J. Kolář, E. Paunzen, M. E. Shultz, M. Skarka, V.N. Aitov, A.S. Beskakotov, R. Brahm, V.V. Dyachenko, L. Eyer, P. Kabáth, O. Kvaratskhelia, T. Kvernadze, J. Lipták, A.V. Moiseeva, V. Schaffenroth, L. Vanzi, J. Žák
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,865
Funders: National Astronomical Research Institute of Thailand, European Space Agency, European Commission, Deutscher Akademischer Austauschdienst, Swedish National Space Agency, Vetenskapsrådet, Centre National de la Recherche Scientifique, Russian Science Foundation, Thailand Science Research and Innovation, Smithsonian Astrophysical Observatory, Institut national des sciences de l'Univers, Wroclawskie Centrum Sieciowo-Superkomputerowe, Politechnika Wroclawska, NextGenerationEU
OpenAlex ID: W7223302269