STEREO observations of HD90386 (RX Sex): a δ-Scuti or a hybrid star?

International Physics Conference at the Anatolian Peak 2016

Ozuyar, D.^1,2 ; Stevens, I.R.^2 ; Whittaker, G.^3 ; Sangaralingam, V.^4

Ankara University, Department of Astronomy and Space Sciences, Ankara, Turkey^1

University of Birmingham, School of Physics and Astronomy, Birmingham, United Kingdom^2

University of Toronto, Toronto

ON, Canada^3

University of Montreal, School of Physics, Montreal, Canada^4

关键词: Amplitude spectra;    Different frequency;    Dominant frequency;    Frequency Analysis;    Higher frequencies;    Internal structure;    Periodic variation;    Rotational effects;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/707/1/012041/pdf
DOI  :  10.1088/1742-6596/707/1/012041

来源: IOP

【 摘 要 】

HD90386 is a rarely studied bright A2V type δ Scuti star (V = 6.66 mag). It displays short-term light curve variations which are originated due to either a beating phenomenon or a non-periodic variation. In this paper, we presented high-precision photometric data of HD90386 taken by the STEREO satellite between 2007 and 2011 to shed light on its internal structure and evolution stage. From the frequency analysis of the four-year data, we detected that HD90386 had at least six different frequencies between 1 and 15 c d-1. The most dominant frequencies were found at around 10.25258 c d-1(A ∼ 1.92 mmag) and 12.40076 c d-1(A ∼ 0.61 mmag). Based on the ratio between these frequencies, the star was considered as an overtone pulsator. The variation in pulsation period over 35 years was calculated to be dP/Pdt = 5.39(2) x 10-3yr-1. Other variabilities at around 1.0 c d-1in the amplitude spectrum of HD90386 were also discussed. In order to explain these variabilities, possible rotational effects and γ Dor type variations were focused. Consequently, depending on the rotation velocity of HD90386, we speculated that these changes might be related to γ Dor type high-order g-modes shifted to the higher frequencies and that HD90386 might be a hybrid star.