TESS asteroseismology of the Kepler red giants

Abstract

Red giant asteroseismology can provide valuable information for studying the Galaxy as demonstrated by space missions like CoRoT and Kepler. However, previous observations have been limited to small data sets and fields-of-view. The TESS mission provides far larger samples and, for the first time, the opportunity to perform asteroseimic inference from full-frame images full-sky, instead of narrow fields and pre-selected targets. Here, we seek to detect oscillations in TESS data of the red giants in the Kepler field using the 4-yr Kepler results as benchmark. Because we use 1-2 sectors of observation, our results are representative of the typical scenario from TESS data. We detect clear oscillations in ∼3000 stars with another ∼1000 borderline (low S/N) cases. In comparison, best-case predictions suggests ∼4500 detectable oscillating giants. Of the clear detections, we measure Δν in 570 stars, meaning a ∼20 per cent Δν yield (14 per cent for one sector and 26 per cent for two sectors). These yields imply that typical (1-2 sector) TESS data will result in significant detection biases. Hence, to boost the number of stars, one might need to use only νmax as the seismic input for stellar property estimation. However, we find little bias in the seismic measurements and typical scatter is about 5–6 per cent in νmax and 2-3 per cent in Δν. These values, coupled with typical uncertainties in parallax, Teff, and [Fe/H] in a grid-based approach, would provide internal uncertainties of 3 per cent in inferred stellar radius, 6 per cent in mass and 20 per cent in age for low-luminosity giant stars. Finally, we find red giant seismology is not significantly affected by seismic signal confusion from blending for stars with Tmag ≲ 12.5.

Gaia Data Release 3

“…Clementini et al 2019;Mowlavi et al 2018;Ripepi et al 2022;Gaia Collaboration et al 2019), but its capacity has not yet been established for the low-amplitude main sequence IHM stars. While the µmag-precision space mis-sions so far resulted in asteroseismic modelling of thousands of red giants (Hon et al 2018;Yu et al 2018Yu et al , 2020Yu et al , 2021Stello et al 2022) and of hundreds of Sun-like dwarfs with masses M ≤ 1.3 M (García & Ballot 2019), the samples of asteroseismically modelled IHM dwarfs are much smaller and do not yet fully cover the parameter space in terms of rotation, binarity, and metallicity. It is in this area that Gaia's time series is helpful and will allow for the discovery of thousands of oscillating IHM candidates, with the aim being to achieve unbiased and complete samples.…”

Frequency Analysis of KIC 1573174: Shedding Light on the Nature of HADS Stars

“…The high-precision photometric data provided by Kepler (e.g., Borucki et al 2010;Koch et al 2010) provides an unprecedented opportunity to explore stellar interiors by using the natural oscillation mode of stars, thus greatly expanding the research field of asteroseismology (e.g., Aerts et al 2010;Chaplin et al 2010;Xue et al 2018;Bowman et al 2021). The ultra-high-precision photometric observations at the μ mag level have significantly advanced our understanding of several types of pulsating variable stars (e.g., Balona et al 2012;Silva Aguirre et al 2015;Stello et al 2022;Szewczuk et al 2022). Bedding et al (2011) proposed that the observed period spacings of gravity modes could be applied to distinguish the hydrogen and helium burning stars in red giants.…”

KIC 5768203: A δ Sct Pulsator Modulated by Rotation and Spots

“…The long time span of the Kepler mission has presented unprecedented frequency resolution, which allows us to detect new stellar features. The TESS mission covers the full sky and is capable of detecting stars closer and brighter than the typical Kepler targets (Stello et al 2021). The sky overlapping between the Kepler and TESS mission is well suited for carrying out astroseismology, as longer time-span data allows detection of more details, more frequencies, which potentially can be used to derive better constraints on the internal structure.…”