Rotational modulation in A and F stars: magnetic stellar spots or convective core rotation?
Article
Henriksen, Andreea I., Antoci, Victoria, Saio, Hideyuki, Cantiello, Matteo, Kjeldsen, Hans, Kurtz, Donald W., Murphy, Simon J., Mathur, Savita, Garcia, Rafael A. and Santos, Angela R. G.. 2023. "Rotational modulation in A and F stars: magnetic stellar spots or convective core rotation?" Monthly Notices of the Royal Astronomical Society. 520 (1), pp. 216-232. https://doi.org/10.1093/mnras/stad153
Article Title | Rotational modulation in A and F stars: magnetic stellar spots or convective core rotation? |
---|---|
ERA Journal ID | 1074 |
Article Category | Article |
Authors | Henriksen, Andreea I., Antoci, Victoria, Saio, Hideyuki, Cantiello, Matteo, Kjeldsen, Hans, Kurtz, Donald W., Murphy, Simon J., Mathur, Savita, Garcia, Rafael A. and Santos, Angela R. G. |
Journal Title | Monthly Notices of the Royal Astronomical Society |
Journal Citation | 520 (1), pp. 216-232 |
Number of Pages | 17 |
Year | 2023 |
Publisher | Oxford University Press |
Place of Publication | United Kingdom |
ISSN | 0035-8711 |
1365-2966 | |
Digital Object Identifier (DOI) | https://doi.org/10.1093/mnras/stad153 |
Web Address (URL) | https://academic.oup.com/mnras/article/520/1/216/6987681 |
Abstract | The Kepler mission revealed a plethora of stellar variability in the light curves of many stars, some associated with magnetic activity or stellar oscillations. In this work, we analyse the periodic signal in 162 intermediate-mass stars, interpreted as Rossby modes and rotational modulation – the so-called hump and spike feature. We investigate whether the rotational modulation (spike) is due to stellar spots caused by magnetic fields or due to Overstable Convective (OsC) modes resonantly exciting g modes, with frequencies corresponding to the convective core rotation rate. Assuming that the spikes are created by magnetic spots at the stellar surface, we recover the amplitudes of the magnetic fields, which are in good agreement with theoretical predictions. Our data show a clear anticorrelation between the spike amplitudes and stellar mass and possibly a correlation with stellar age, consistent with the dynamo-generated magnetic fields theory in (sub)-surface convective layers. Investigating the harmonic behaviour, we find that for 125 stars neither of the two possible explanations can be excluded. While our results suggest that the dynamo-generated magnetic field scenario is more likely to explain the spike feature, we assess further work is needed to distinguish between the two scenarios. One method for ruling out one of the two explanations is to directly observe magnetic fields in hump and spike stars. Another would be to impose additional constraints through detailed modelling of our stars, regarding the rotation requirement in the OsC mode scenario or the presence of a convective-core (stellar age). |
Keywords | stars: early-type; stars: rotation; stars: magnetic field; stars: oscillations |
ANZSRC Field of Research 2020 | 510109. Stellar astronomy and planetary systems |
Public Notes | This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society © 2023 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. |
Byline Affiliations | Technical University of Denmark, Denmark |
Tohoku University, Japan | |
Flatiron Institute, United States | |
Aarhus University, Denmark | |
North-West University, South Africa | |
University of Central Lancashire, United Kingdom | |
Centre for Astrophysics | |
Instituto de Astrof´ısica de Canarias (IAC), Spain | |
University of La Laguna, Spain | |
Paris-Saclay University, France | |
Paris Diderot University, France | |
University of Porto, Portugal |
Permalink -
https://research.usq.edu.au/item/z25yv/rotational-modulation-in-a-and-f-stars-magnetic-stellar-spots-or-convective-core-rotation
Download files
115
total views16
total downloads0
views this month0
downloads this month