Do Metallic-Line A (Am) Stars Pulsate? Results from TESS Cycles 1-3

Metallic-line A (Am) stars are main-sequence stars of around twice the mass of the Sun that show element abundance peculiarities in their spectra.  The radiative levitation and diffusive settling processes responsible for these abundance anomalies should also deplete helium from the region of the envelope that drives delta Scuti p-mode pulsations via the kappa (opacity) mechanism.  Therefore, these stars are not expected to pulsate in multiple radial and nonradial modes with periods of around 2 hours, characteristic of delta Scuti stars.  As part of the TESS Guest Investigator programs Cycles 2 and 3, we proposed observations in 2-minute cadence of bright (visual magnitudes 7-8) Am stars.  As of March 2021, 55 target stars have been observed; among them we find four delta Scuti stars and four delta Scuti/gamma Doradus hybrid candidates, as well as many stars showing variability possibly caused by rotation and starspots.  Confirming the pulsations will require further analysis and follow-up, including ruling out contamination from background or nearby stars in the field.  Asteroseismic modeling of these stars will be useful to understand the reasons for their pulsations and the connections to their abundance peculiarities.