Abstract
ABSTRACT The NASA Transiting Exoplanet Survey Satellite (NASA-TESS) mission presents a treasure trove for understanding the stars it observes and the Milky Way, in which they reside. We present a first look at the prospects for Galactic and stellar astrophysics by performing initial asteroseismic analyses of bright (G < 11) red giant stars in the TESS southern continuous viewing zone (SCVZ). Using three independent pipelines, we detect νmax and Δν in 41 per cent of the 15 405 star parent sample (6388 stars), with consistency at a level of $\sim \! 2{{\ \rm per\ cent}}$ in νmax and $\sim \! 5{{\ \rm per\ cent}}$ in Δν. Based on this, we predict that seismology will be attainable for ∼3 × 105 giants across the whole sky and at least 104 giants with ≥1 yr of observations in the TESS-CVZs, subject to improvements in analysis and data reduction techniques. The best quality TESS-CVZ data, for 5574 stars where pipelines returned consistent results, provide high-quality power spectra across a number of stellar evolutionary states. This makes possible studies of, for example, the asymptotic giant branch bump. Furthermore, we demonstrate that mixed ℓ = 1 modes and rotational splitting are cleanly observed in the 1-yr data set. By combining TESS-CVZ data with TESS-HERMES, SkyMapper, APOGEE, and Gaia, we demonstrate its strong potential for Galactic archaeology studies, providing good age precision and accuracy that reproduces well the age of high [α/Fe] stars and relationships between mass and kinematics from previous studies based on e.g. Kepler. Better quality astrometry and simpler target selection than the Kepler sample makes this data ideal for studies of the local star formation history and evolution of the Galactic disc. These results provide a strong case for detailed spectroscopic follow-up in the CVZs to complement that which has been (or will be) collected by current surveys.
Highlights
Asteroseismology, the study of stellar oscillations, made possible through space based, long duration photometry of stars in missions such as CoRoT (Baglin et al 2006; Auvergne et al 2009), Kepler (Borucki et al 2010) and K2 (Howell et al 2014) has brought about a paradigm shift in our understanding of stellar structure and evolution
By selecting a sample of very bright (G < 11) giant stars based on Gaia DR2 (Gaia Collaboration et al 2018) and 2MASS (Skrutskie et al 2006) photometry, we demonstrate that the detection of stellar oscillations in the continuous viewing zones (CVZ) data across many evolutionary stages on the giant branch will allow detailed studies of stellar structure
We have demonstrated the strong potential for Galactic archaeology and stellar astrophysics and asteroseismic quality of year-long photometry from the Transiting Exoplanet Survey Satellite (TESS)-CVZ
Summary
Asteroseismology, the study of stellar oscillations, made possible through space based, long duration photometry of stars in missions such as CoRoT (Baglin et al 2006; Auvergne et al 2009), Kepler (Borucki et al 2010) and K2 (Howell et al 2014) has brought about a paradigm shift in our understanding of stellar structure and evolution. Asteroseismic ages have already proven extremely useful in understanding aspects of the formation and evolution of the Milky Way disc (Anders et al 2017b; Silva Aguirre et al 2018; Miglio et al 2020) and more recently, the halo (Chaplin et al 2020; Montalbán et al 2020). Extending the sample size and better measuring and understanding the stars in these vital training data will no doubt play a key role in the future of asteroseismology-driven Galactic studies. Such multi-dimensional data sets, observed by multiple surveys, provide an ideal means by which to calibrate data between surveys
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