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Periodic stellar variability from almost a million NGTS light curves

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posted on 2025-06-30, 10:46 authored by Joshua T Briegal, Edward Gillen, Didier Queloz, Simon Hodgkin, Jack S Acton, David R Anderson, David J Armstrong, Matthew P Battley, Daniel Bayliss, Matthew BurleighMatthew Burleigh, Edward M Bryant, Sarah CasewellSarah Casewell, Jean C Costes, Philipp Eigmuller, Samuel Gill, Michael GoadMichael Goad, Maximilian N Gunther, Beth A Henderson, James AG Jackman, James S Jenkins, Lars T Kreutzer, Maximiliano Moyano, Monika Lendl, Gareth D Smith, Rosanna H Tilbrook, Christopher A Watson, Richard G West, Peter J Wheatley

We analyse 829 481 stars from the Next Generation Transit Survey (NGTS) to extract variability periods. We utilize a generalization of the autocorrelation function (the G-ACF), which applies to irregularly sampled time series data. We extract variability periods for 16 880 stars from late-A through to mid-M spectral types and periods between ∼0.1 and 130 d with no assumed variability model. We find variable signals associated with a number of astrophysical phenomena, including stellar rotation, pulsations, and multiple-star systems. The extracted variability periods are compared with stellar parameters taken from Gaia DR2, which allows us to identify distinct regions of variability in the Hertzsprung–Russell Diagram. We explore a sample of rotational main-sequence objects in period-colour space, in which we observe a dearth of rotation periods between 15 and 25 d. This ‘bi-modality’ was previously only seen in space-based data. We demonstrate that stars in sub-samples above and below the period gap appear to arise from a stellar population not significantly contaminated by excess multiple systems. We also observe a small population of long-period variable M-dwarfs, which highlight a departure from the predictions made by rotational evolution models fitted to solar-type main-sequence objects. The NGTS data spans a period and spectral type range that links previous rotation studies such as those using data from Kepler, K2, and MEarth.

History

Author affiliation

College of Science & Engineering Physics & Astronomy

Version

  • VoR (Version of Record)

Published in

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

Volume

513

Issue

1

Pagination

420 - 438 (19)

Publisher

OXFORD UNIV PRESS

issn

0035-8711

eissn

1365-2966

Copyright date

2022

Available date

2025-06-30

Language

English

Deposited by

Dr Michael Goad

Deposit date

2025-05-23

Data Access Statement

The NGTS data underlying this article are publicly available through the ESO Archive in line with the NGTS data publication policy. The variability period results produced in this article are available as supplementary material and at CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via https://cdsarc.unistra.fr/viz-bin/cat/J/MNRAS.