Activity and differential rotation of the early M dwarf Kepler-45 from transit mapping

Autor(es)

Zaleski, S. M. ^[1] ; Valio, A. ^[2] ; Carter, B. D. ^[1] ; Marsden, S. C. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Southern Queensland, Ctr Astrophys, Toowoomba, Qld 4350 - Australia

^[2] Univ Prebiteriana Mackenzie, Ctr Radio Astron & Astrophys, Rua Consolacao 896, BR-01302907 Sao Paulo, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Monthly Notices of the Royal Astronomical Society; v. 492, n. 4, p. 5141-5151, MAR 2020.
• Citações Web of Science: 2

Resumo

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 x 103 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 01'7.8 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. (AU)

• Processo FAPESP: 13/10559-5 - Investigação de fenômenos de altas energias e plasmas astrofísicos: teoria, simulações numéricas, observações e desenvolvimento de instrumentação para o Cherenkov Telescope Array (CTA)
• Beneficiário: Elisabete Maria de Gouveia Dal Pino
• Modalidade de apoio: Auxílio à Pesquisa - Projetos Especiais