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

TL;DR

This study uses TESS data to analyze delta Scuti stars in the Pleiades cluster, revealing high pulsation fractions, the impact of rotation, and challenging existing pulsation models for young stars.

Contribution

It provides the first comprehensive TESS-based survey of delta Scuti stars in the Pleiades, highlighting their pulsation properties and the effects of reddening and rotation.

Findings

Over 80% of stars in the instability strip pulsate.

Pulsation spectra vary and do not correlate with temperature.

The instability strip shifts with interstellar reddening.

Abstract

We studied 89 A- and F-type members of the Pleiades open cluster, including five escaped members. We measured projected rotational velocities (v sin i) for 49 stars and confirmed that stellar rotation causes a broadening of the main sequence in the color-magnitude diagram. Using time-series photometry from NASA's TESS Mission (plus one star observed by Kepler/K2), we detected delta Scuti pulsations in 36 stars. The fraction of Pleiades stars in the middle of the instability strip that pulsate is unusually high (over 80%), and their range of effective temperatures agrees well with theoretical models. On the other hand, the characteristics of the pulsation spectra are varied and do not correlate with stellar temperature, calling into question the existence of a useful nu_max relation for delta Scutis, at least for young stars. By including delta Scuti stars observed in the Kepler field, we show that the instability strip is shifted to the red with increasing distance by interstellar reddening. Overall, this work demonstrates the power of combining observations with Gaia and TESS for studying pulsating stars in open clusters.