Issue |
A&A
Volume 694, February 2025
|
|
---|---|---|
Article Number | A270 | |
Number of page(s) | 5 | |
Section | Stellar atmospheres | |
DOI | https://doi.org/10.1051/0004-6361/202453189 | |
Published online | 19 February 2025 |
Horizontal flows in the atmospheres of chemically peculiar stars
1
Penn State Scranton,
120 Ridge View Drive,
Dunmore,
PA
18512,
USA
2
Department of Theoretical Physics and Astrophysics, Masaryk University,
Kotlářská 2,
611 37
Brno,
Czech Republic
3
Astronomical Institute of the Czech Academy of Sciences,
Fričova 298,
251 65
Ondřejov,
Czech Republic
★ Corresponding author; asif@psu.edu
Received:
27
November
2024
Accepted:
22
January
2025
Context. Classical chemically peculiar stars exhibit atmospheres that are often structured by the effects of atomic diffusion. As a result of these elemental diffusion and horizontal abundance variations, the photospheric temperature varies at a given height in the atmosphere. This may lead to horizontal flows in the photosphere. In addition, the suppression of such flows by a magnetic field can alter the elemental transport processes.
Aims. Using a simplified model of such a structured atmosphere and 2D magnetohydrodynamic simulations of a typical He-rich star, we examined atmospheric flows in these chemically peculiar stars, which often are strongly magnetic.
Methods. We used Zeus-MP, which is a publicly available Fortran 90-based parallel finite element modular code.
Results. We find that for non-magnetic stars of spectral type BA, the atmospheric flow related to the horizontal temperature gradient can reach 1.0 km s−1, yielding mixing timescales of the order of tens of days. For the magnetic counterparts, the flow speeds are an order of magnitude lower, allowing for the stratification of chemical elements.
Conclusions. Magnetic fields can significantly influence the dynamics in atmospheres. A strong horizontal magnetic field inhibits flow in the vertical direction, while a strong vertical magnetic field can suppress horizontal atmospheric flow and prevent elemental mixing.
Key words: stars: chemically peculiar / circumstellar matter / stars: early-type / stars: general / stars: magnetic field / stars: variables: general
© The Authors 2025
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
This article is published in open access under the Subscribe to Open model. Subscribe to A&A to support open access publication.
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.