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A BRITE view on the massive O-type supergiant V973 Scorpii: Hints towards internal gravity waves or sub-surface convection zones

Lookup NU author(s): Dr Rathish Ratnasingam, Professor Tamara Rogers

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Abstract

© 2018 The Author(s). Stochastically triggered photospheric light variations reaching ~40 mmag peak-to-valley amplitudes have been detected in the O8 Iaf supergiant V973 Scorpii as the outcome of 2 months of high-precision time-resolved photometric observations with the BRIght Target Explorer (BRITE) nanosatellites. The amplitude spectrum of the time series photometry exhibits a pronounced broad bump in the low-frequency regime (≲0.9 d-1) where several prominent frequencies are detected. A time-frequency analysis of the observations reveals typical mode lifetimes of the order of 5-10 d. The overall features of the observed brightness amplitude spectrum ofV973 Sco matchwellwith those extrapolated from two-dimensional hydrodynamical simulations of convectively driven internal gravity waves randomly excited from deep in the convective cores of massive stars. An alternative or additional possible source of excitation from a sub-surface convection zone needs to be explored in future theoretical investigations.

Publication metadata

Author(s): Ramiaramanantsoa T, Ratnasingam R, Shenar T, Moffat AFJ, Rogers TM, Popowicz A, Kuschnig R, Pigulski A, Handler G, Wade GA, Zwintz K, Weiss WW

Publication type: Article

Publication status: Published

Journal: Monthly Notices of the Royal Astronomical Society

Year: 2018

Volume: 480

Issue: 1

Pages: 972-986

Print publication date: 11/10/2018

Online publication date: 19/07/2018

Acceptance date: 17/07/2018

ISSN (print): 0035-8711

ISSN (electronic): 1365-2966

Publisher: Oxford University Press

URL: https://doi.org/10.1093/MNRAS/STY1897

DOI: 10.1093/MNRAS/STY1897

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