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TESS observations of the Pleiades cluster: a nursery for delta Scuti stars

Timothy R. BeddingSimon J. MurphyCourtney Crawford ...+7 George Zhou
Dec 2022
We studied 89 A- and F-type members of the Pleiades open cluster, includingfive escaped members. We measured projected rotational velocities (v sin i) for49 stars and confirmed that stellar rotation causes a broadening of the mainsequence in the color-magnitude diagram. Using time-series photometry fromNASA's TESS Mission (plus one star observed by Kepler/K2), we detected deltaScuti pulsations in 36 stars. The fraction of Pleiades stars in the middle ofthe instability strip that pulsate is unusually high (over 80%), and theirrange of effective temperatures agrees well with theoretical models. On theother hand, the characteristics of the pulsation spectra are varied and do notcorrelate with stellar temperature, calling into question the existence of auseful nu_max relation for delta Scutis, at least for young stars. By includingdelta Scuti stars observed in the Kepler field, we show that the instabilitystrip is shifted to the red with increasing distance by interstellar reddening.Overall, this work demonstrates the power of combining observations with Gaiaand TESS for studying pulsating stars in open clusters.