TY  - JOUR
A1  - Ramiaramanantsoa, Tahina
A1  - Ratnasingam, Rathish
A1  - Shenar, Tomer
A1  - Moffat, Anthony F. J.
A1  - Rogers, Tamara M.
A1  - Popowicz, Adam
A1  - Kuschnig, Rainer
A1  - Pigulski, Andrzej
A1  - Handler, Gerald
A1  - Wade, Gregg A.
A1  - Zwintz, Konstanze
A1  - Weiss, Werner W.
T1  - A BRITE view on the massive O-type supergiant V973 Scorpii
BT  - hints towards internal gravity waves or sub-surface convection zones
JF  - Monthly notices of the Royal Astronomical Society
N2  - Stochastically triggered photospheric light variations reaching similar to 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 (less than or similar to 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 of V973 Sco match well with 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.
KW  - convection
KW  - waves
KW  - techniques: photometric
KW  - stars: massive
KW  - supergiants
Y1  - 2018
U6  - https://doi.org/10.1093/mnras/sty1897
SN  - 0035-8711
SN  - 1365-2966
VL  - 480
IS  - 1
SP  - 972
EP  - 986
PB  - Oxford Univ. Press
CY  - Oxford
ER  -