A Frequency Analysis of the δ Scuti Variable Star BG Hydri

Volume 52 number 1 (2024)

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Bill Rea

Richmond, New Zealand; rea.william@gmail.com

Abstract

We present a frequency analysis of data from NASA’s Transiting Exoplanet Survey Satellite (TESS) for the southern δ Scuti variable star BG Hyi and compare the results with those published in the discovery paper of 1980. We confirm the presence of four strong frequencies grouped in two pairs and show that they are not combination frequencies. However, we also show that the two pairs of frequencies are separated by statistically different splits, implying that if they are rotationally split modes as conjectured in the discovery paper, the modes are not the same for both pairs. We further show that some frequencies have undergone amplitude modulation on both long and short time scales. In common with many other δ Scuti stars we report low amplitude, low statistically significant frequencies in the region between the top of the γ Dor and the bottom of the δ Scuti frequencies which cannot be explained as combinations of other significant frequencies and which currently do not have an adequate physical explanation.