Identifying 850 δ Scuti pulsators in a narrow <i>Gaia</i> colour range with <i>TESS</i> 10-min full-frame images
Amelie K. Read, T. R. Bedding, Prasad Mani, Benjamin T. Montet, Courtney L. Crawford, Daniel Hey, Yaguang Li, Simon J. Murphy, M. G. Pedersen, Joachim Krüger
Abstract
ABSTRACT We use TESS 10-min full-frame images (Sectors 27–55) to study a sample of 1708 stars within 500 pc of the Sun that lie in a narrow colour range in the centre of the δ Scuti instability strip (0.29 &lt; GBP − GRP &lt; 0.31). Based on the Fourier amplitude spectra, we identify 848 δ Scuti stars, as well as 47 eclipsing or contact binaries. The strongest pulsation modes of some δ Scuti stars fall on the period–luminosity relation of the fundamental radial mode but many correspond to overtones that are approximately a factor of two higher in frequency. Many of the low-luminosity δ Scuti stars show a series of high-frequency modes with very regular spacings. The fraction of stars in our sample that show δ Scuti pulsations is about 70 per cent for the brightest stars (G &lt; 8), consistent with results from Kepler. However, the fraction drops to about 45 per cent for fainter stars and we find that a single sector of TESS data only detects the lowest amplitude δ Scuti pulsations (around 50 ppm) in stars down to about G = 9. Finally, we have found four new high-frequency δ Scuti stars with very regular mode patterns, and have detected pulsations in λ Mus that make it the fourth-brightest δ Scuti in the sky (G = 3.63). Overall, these results confirm the power of TESS and Gaia for studying pulsating stars.