Activity and differential rotation of the early M dwarf Kepler-45 from transit mapping
Article
Article Title | Activity and differential rotation of the early M dwarf Kepler-45 from transit mapping |
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ERA Journal ID | 1074 |
Article Category | Article |
Authors | Zaleski, S. M. (Author), Valio, A. (Author), Carter, B. D. (Author) and Marsden, S. C. (Author) |
Journal Title | Monthly Notices of the Royal Astronomical Society |
Journal Citation | 492 (4), pp. 5141-5151 |
Number of Pages | 11 |
Year | 2020 |
Publisher | Oxford University Press |
Place of Publication | United Kingdom |
ISSN | 0035-8711 |
1365-2966 | |
Digital Object Identifier (DOI) | https://doi.org/10.1093/mnras/staa103 |
Web Address (URL) | https://academic.oup.com/mnras/article/492/4/5141/5706859 |
Abstract | Little is known of the activity and differential rotation of low luminosity, early M dwarfs from direct observation. We present the first stellar activity analysis of star-spots and faculae for the hot Jupiter hosting M1V dwarf Kepler-45 from Kepler transit light curves. We find star-spot and facula temperatures contrasting a few hundred degrees with the quiet photosphere, hence similar to other early M dwarfs having a convective envelope surrounding a radiative core. Star-spots are prominent close to the centre of the stellar disc, with faculae prominent towards the limbs, similar to what is observed for the Sun. Star-spot and facula mean sizes are about 40 and 45 × 10^3 km, respectively, and thus faculae occupy a 10 per cent larger surface area than the star-spots. A short-term activity cycle of about 295 d is observed that is reminiscent of those seen for other cool dwarfs. Adopting a solar-type differential rotation profile (faster equatorial rotation than polar rotation), our star-spot and facula temporal mapping indicates a rotation period of 15.520 ± 0.025 d at the transit latitude of −33.2◦. From the mean stellar rotation of 15.762 d, we estimate a rotational shear of 0.031 ± 0.004 rad d^−1, or a relative differential rotation of 7.8 ± 0.9 per cent. Kepler-45’s surface rotational shear is thus consistent with observations and theoretical modelling of other early M dwarfs that indicate a shear of less than 0.045 rad d^−1 and no less than 0.03 rad d^−1 for stars with similar stellar rotation periods. |
Keywords | stars: activity – stars: solar-type – starspots |
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 ©: 2020 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. |
Byline Affiliations | Centre for Astrophysics |
Mackenzie Presbyterian University, Brazil | |
Institution of Origin | University of Southern Queensland |
https://research.usq.edu.au/item/q6068/activity-and-differential-rotation-of-the-early-m-dwarf-kepler-45-from-transit-mapping
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