A Weak Modulation Effect Detected in the Light Curves of KIC 5950759: Intrinsic or Instrumental Effect?

TL;DR

This study analyzes Kepler light curves of KIC 5950759, revealing a weak modulation effect likely caused by stellar rotation, marking the first detection of such modulation in a double-mode HADS star.

Contribution

First detection of modulation effect in a double-mode HADS star, suggesting amplitude modulation linked to stellar rotation.

Findings

Detected three independent frequencies in KIC 5950759.

Identified weak modulation (triplet structures) in light curves.

Proposed rotation-related amplitude modulation as the cause.

Abstract

In this paper, the high-precision light curves of $Kepler$ target KIC 5950759 are analyzed. The Fourier analysis of the long cadence light curve reveals 3 independent frequencies. Two of them are main pulsation modes: F0 = 14.221373(21) $\rm{d^{-1}}$ and F1 = 18.337249(44) $\rm{d^{-1}}$. The third independent frequency $f_m$ = 0.3193 d$^{-1}$ is found in long cadence data with a signal-to-noise ratio of 6.2. A weak modulation of $f_m$ to F0 and F1 modes (triplet structures centred on F0 and F1) are detected both in long and short cadence data. This is the first detection of the modulation effect in a double-mode HADS star. The most possible cause of the modulation effect in the light curves is amplitude modulation with the star's rotation frequency of 0.3193 d$^{-1}$. The preliminary analysis suggests that KIC 5950759 is in the bottom of the HADS instability strip and likely situated in the main sequence. Spectroscopic observations are necessary to verify the true nature of the modulation terms.