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arXiv · 2301.05367

Surface magnetic field of the A-type metallic-line star omicron Pegasi revisited

Yoichi Takeda
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Abstract

The bright A-type metallic-line star o Peg was reported in the early 1990s to have a surface magnetic field of ~2kG by analyzing the widths and strengths of spectral lines. In respect that those old studies were of rather empirical or approximate nature and the quality of observational data was not sufficient, this problem has been newly reinvestigated based on physically more rigorous simulations of line flux profiles, along with the observed equivalent widths (W) and full-widths at half-maximum (h) of 198 Fe I and 182 Fe II lines measured from the high-quality spectra. Given the Fe abundance derived from the conventional analysis, theoretical W and h values calculated for various sets of parameters were compared with the observed ones, which lead to the following conclusion regarding (mean field strength). (1) An analysis of W yielded ~1-1.5kG from Fe II lines with the microturbulence of vt~1.5km/s. (2) A comparison of h resulted in ~1.5-2kG as well as the projected rotational velocity of vsini~5km/s. (3) Accordingly, the existence of mean magnetic field on the order of ~1-2kG in o Peg was confirmed, which is almost consistent with the consequence of the previous work.

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Yoichi Takeda. 2023-01-13. Surface magnetic field of the A-type metallic-line star omicron Pegasi revisited. https://doi.org/10.1002/asna.20220057

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