Long-period Ap stars discovered with TESS data

We successfully applied this method to the analysis of the TESS 2-min cadence observations of Ap stars of the southern ecliptic hemisphere. For our present study, we applied the same approach to the analysis of the TESS 2-min cadence observations of Ap stars of the northern ecliptic hemisphere. We confirm that the technique leads to the reliable identification of ssrAp star candidates in an unbiased manner.

We find 67 Ap stars with no rotational variability in the northern ecliptic hemisphere TESS data. Among them, 46 are newly identified ssrAp star candidates, which is double the number found in the southern ecliptic hemisphere. We confirm that super-slow rotation tends to occur less frequently in weakly magnetic Ap stars than in strongly magnetic stars.

We present new evidence of the existence of a gap between ~2 kG and ~3 kG in the distribution of the magnetic field strengths of long period Ap stars. We also confirm that the incidence of roAp stars is higher than average in slowly rotating Ap stars. We report the unexpected discovery of nine definite and five candidate {delta} Sct stars, and of two eclipsing binaries.

This work paves the way for a systematic, unbiased study of the longest period Ap stars, with a view to characterise the correlations between their rotational, magnetic, and pulsational properties.