6685 20240612103614.0 10.25518/0037-9565.11678 DOI SCART-2024-0053 Sarkar, Mrinmoy Amplitude Modulation in a δ Scuti star HD 118660 2024 In this paper, we report the detection of amplitude modulation in a δ Scuti star HD118660. We found that the p-mode frequency at 24.3837 d^{−1} varies periodically in amplitude with frequency 0.0558 ± 0.00147 d^{−1}. However, all other modes are stable in both amplitude and phase which is clear evidence of non-conservation of visible pulsation mode energy. We constructed a two-frequency model by superimposing two sinusoïds with frequencies ν_1 = 24.3837 d^{−1} and ν_2 = 24.4420 d^{−1} and corresponding phases φ_1 = 0.5211 rad and φ_2 = 0.9481 rad to mimic the observed variations of amplitude and phase with time. The plausible explanation of the amplitude modulation in HD 118660 is due to beating of two unresolved closed frequencies ν_1 and ν_2. BL/ 33/ IN12 (BINA) NO Stars: individual: HD118660 Stars: amplitude modulation TESS: δ Scuti pulsator Chemically peculiar Stars: oscillations Joshi, Santosh De Cat, Peter Bulletin de la Société Royale des Sciences de Liège 93 2024 2 285--293 peter.decat@ksb-orb.be 1524841 http://publi2-as.oma.be/record/6685/files/23bina_Poster_Sarakar.pdf 12801 http://publi2-as.oma.be/record/6685/files/23bina_Poster_Sarakar.jpg?subformat=icon-180 icon-180 29151 http://publi2-as.oma.be/record/6685/files/23bina_Poster_Sarakar.gif?subformat=icon icon 363157 http://publi2-as.oma.be/record/6685/files/Sarkar2024_BSRSL93_2_285.pdf 2939 http://publi2-as.oma.be/record/6685/files/Sarkar2024_BSRSL93_2_285.jpg?subformat=icon-180 icon-180 3141 http://publi2-as.oma.be/record/6685/files/Sarkar2024_BSRSL93_2_285.gif?subformat=icon icon published in REFERD