Signature of High-amplitude Pulsations in Seven δ Sct Stars via TESS Observations

Abstract

The regular behavior of the pulsations of high-amplitude δ Sct (HADS) stars gives a greater chance to investigate the interiors of stars. We analyzed seven HADS stars showing peak-to-peak amplitudes of more than 0.3 mag that were newly observed by TESS. We obtained that TIC 374753270, TIC 710783, and TIC 187386415 pulsate in fundamental radial mode; also, TIC 130474019 and TIC 160120432 show double radial modes. On the other hand, TIC 148357344 and TIC 278119167 demonstrate triple-mode behavior. Our analysis shows that these seven stars are close to the red edge of the (inside) instability strip in the Hertzsprung–Russell diagram. The fundamental mode of these seven targets follows the period–luminosity (PL) relation for δ Sct stars. However, TIC 278119167 deviates slightly from the fundamental PL relation. The double-mode and triple-mode HADS stars (TIC 130474019, TIC 160120432, TIC 148357344, and TIC 278119167) are in agreement with the period ratio ranges (fundamental to first and second overtones). Using the information of 176 HADS stars (Netzel and Smolec), we find a scaling relation ( $[\mathrm{Fe}/{\rm{H}}]\propto \mathrm{log}({M}^{7.95\pm 0.15}{L}^{-1.83\pm 0.11}{\rm{P}}{0}^{0.79\pm 0.14}{T}_{\mathrm{eff}}^{0.047\pm 0.02}$ )) between the metallicity ([Fe/H]) and mass ( M ), luminosity ( L ), effective temperature ( T _eff ), and the fundamental period (P0). We estimate the metallicity of the seven newly identified HADS stars ranging from −0.62 to 0.37 dex.

Keywords

• Asteroseismology
• Stellar oscillations
• Delta Scuti variable stars