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On the relation between active-region lifetimes and the autocorrelation function of light curves
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Santos, A. R. G., Mathur, S., Garcia, R. A., Cunha, M. S. and Avelino, P. P. (2021) On the relation between active-region lifetimes and the autocorrelation function of light curves. Monthly Notices of the Royal Astronomical Society, 508 (1). pp. 267-278. doi:10.1093/mnras/stab2402
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Official URL: https://doi.org/10.1093/mnras/stab2402
Abstract
Rotational modulation of stellar light curves due to dark spots encloses information on spot properties and, thus, on magnetic activity. In particular, the decay of the autocorrelation function (ACF) of light curves is presumed to be linked to spot/active-region lifetimes, given that some coherence of the signal is expected throughout their lifetime. In the literature, an exponential decay has been adopted to describe the ACF. Here, we investigate the relation between the ACF and the active-region lifetimes. For this purpose, we produce artificial light curves of rotating spotted stars with different observation, stellar, and spot properties. We find that a linear decay and respective time-scale better represent the ACF than the exponential decay. We therefore adopt a linear decay. The spot/active-region time-scale inferred from the ACF is strongly restricted by the observation length of the light curves. For 1-yr light curves our results are consistent with no correlation between the inferred and the input time-scales. The ACF decay is also significantly affected by differential rotation and spot evolution: strong differential rotation and fast spot evolution contribute to a more severe underestimation of the active-region lifetimes. Nevertheless, in both circumstances the observed time-scale is still correlated with the input lifetimes. Therefore, our analysis suggests that the ACF decay can be used to obtain a lower limit of the active-region lifetimes for relatively long-term observations. However, strategies to avoid or flag targets with fast active-region evolution or displaying stable beating patterns associated with differential rotation should be employed.
| Item Type: | Journal Article | ||||||||||||||||||||||||||||||||||||
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| Subjects: | Q Science > QB Astronomy | ||||||||||||||||||||||||||||||||||||
| Divisions: | Faculty of Science > Physics | ||||||||||||||||||||||||||||||||||||
| SWORD Depositor: | Library Publications Router | ||||||||||||||||||||||||||||||||||||
| Library of Congress Subject Headings (LCSH): | Low mass stars, Starspots , Variable stars -- Light curves | ||||||||||||||||||||||||||||||||||||
| Journal or Publication Title: | Monthly Notices of the Royal Astronomical Society | ||||||||||||||||||||||||||||||||||||
| Publisher: | Oxford University Press (OUP) | ||||||||||||||||||||||||||||||||||||
| ISSN: | 1365-2966 | ||||||||||||||||||||||||||||||||||||
| Official Date: | November 2021 | ||||||||||||||||||||||||||||||||||||
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| Volume: | 508 | ||||||||||||||||||||||||||||||||||||
| Number: | 1 | ||||||||||||||||||||||||||||||||||||
| Page Range: | pp. 267-278 | ||||||||||||||||||||||||||||||||||||
| DOI: | 10.1093/mnras/stab2402 | ||||||||||||||||||||||||||||||||||||
| Status: | Peer Reviewed | ||||||||||||||||||||||||||||||||||||
| Publication Status: | Published | ||||||||||||||||||||||||||||||||||||
| Publisher Statement: | This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society © 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society | ||||||||||||||||||||||||||||||||||||
| Access rights to Published version: | Restricted or Subscription Access | ||||||||||||||||||||||||||||||||||||
| RIOXX Funder/Project Grant: |
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