We started by developing a Gaussian process regression framework to model granulation and oscillations in red-giant stars. This method is capable of describing stellar signals while simultaneously modeling an exoplanet's transit. The implementation of the method was described in Pereira, Campante et al. (2019,
https://arxiv.org/abs/1908.10662(odnośnik otworzy się w nowym oknie)) and the corresponding software tool (gptransits) made freely available through GitHub.
The open-source software eleanor was then used to produce photometric time series for all available sectors of TESS data for each target star. We conducted an automated transit search on TESS light curves of approximately 100,000 red giants, with a focus on close-in giant planets. The automated search procedure was extensively tested prior to the first science data release (Campante et al. 2018,
https://zenodo.org/record/2463210#.X7fZLdW2yOE(odnośnik otworzy się w nowym oknie)). The transit search was complemented by a vetting and ranking procedure aimed at distinguishing the expected transit-like features from astrophysical false positives and systematic false alarms. The first detection of a TESS giant planet transiting an oscillating red giant was reported in Huber et al. (2019,
https://arxiv.org/abs/1901.01643(odnośnik otworzy się w nowym oknie)). This was followed by the detection of a warm sub-Saturn around an evolved F-type star (Addison et al. 2020,
https://arxiv.org/abs/2001.07345(odnośnik otworzy się w nowym oknie)).
Furthermore, a total of three known radial-velocity planets were discovered to transit from TESS observations (Kane et al. 2020,
https://arxiv.org/abs/2007.10995(odnośnik otworzy się w nowym oknie); Pepper et al. 2020,
https://arxiv.org/abs/1911.05150(odnośnik otworzy się w nowym oknie)). The number of radial-velocity planets found to transit during TESS's primary mission is aligned with the predictions of Dalba et al. (2019,
https://arxiv.org/abs/1811.06550(odnośnik otworzy się w nowym oknie)).
TESS's excellent photometric precision enables asteroseismology of red-giant stars (Schofield et al. 2019,
https://arxiv.org/abs/1901.10148(odnośnik otworzy się w nowym oknie)). TESS photometry thus offers the prospect of conducting asteroseismology of evolved host stars (Kane, Bean, Campante et al. 2020,
https://arxiv.org/abs/2010.15164(odnośnik otworzy się w nowym oknie)). We estimated global asteroseismic parameters by applying Fourier-based automated methods (Campante et al. 2019,
https://arxiv.org/abs/1909.05961(odnośnik otworzy się w nowym oknie)) to the frequency-power spectra of the target stars. These methods had previously been extensively applied to Kepler/K2 data (Chontos et al. 2019,
https://arxiv.org/abs/1903.01591(odnośnik otworzy się w nowym oknie); Kuszlewicz et al. 2019a,
https://arxiv.org/abs/1905.00040(odnośnik otworzy się w nowym oknie); Kuszlewicz et al. 2019b,
https://arxiv.org/abs/1907.01565(odnośnik otworzy się w nowym oknie); Santos, Campante et al. 2019,
https://arxiv.org/abs/1908.02897(odnośnik otworzy się w nowym oknie); Thomas et al. 2019,
https://arxiv.org/abs/1903.04998(odnośnik otworzy się w nowym oknie)). TESS first-light results (Silva Aguirre et al. 2020,
https://arxiv.org/abs/1912.07604(odnośnik otworzy się w nowym oknie)) in the buildup to which these same methods were employed, clearly demonstrated the potential of TESS for carrying out asteroseismic ensemble studies of red giants. This potential was recently realized by using TESS asteroseismology to age date the early merging of the Milky Way with the Gaia-Enceladus dwarf galaxy (Chaplin et al. 2020,
https://arxiv.org/abs/2001.04653(odnośnik otworzy się w nowym oknie)).
We next determined fundamental stellar properties through a grid-based, forward modeling approach using the Bayesian code AIMS (Rendle et al. 2019,
https://arxiv.org/abs/1901.02663(odnośnik otworzy się w nowym oknie)). To ensure that fundamental properties are derived with the highest possible accuracy, we explored the impact of key physical processes, as well as of the chemical composition (Adibekyan et al. 2020,
https://arxiv.org/abs/2008.08371(odnośnik otworzy się w nowym oknie)) on the stellar properties inferred from forward modeling (Nsamba, Campante et al. 2018,
https://arxiv.org/abs/1812.00431(odnośnik otworzy się w nowym oknie); Nsamba, Campante et al. 2019,
https://arxiv.org/abs/1904.01560(odnośnik otworzy się w nowym oknie); Nsamba, Moedas, Campante et al. 2020,
https://arxiv.org/abs/2010.07593(odnośnik otworzy się w nowym oknie)).
Moreover, several known evolved hosts have benefited from TESS's precision photometry. Campante et al. (2019,
https://arxiv.org/abs/1909.05961(odnośnik otworzy się w nowym oknie)) reported the first detections of oscillations in known hosts by TESS. Other detections of solar-like oscillations in known hosts were reported by Ball et al. (2020,
https://arxiv.org/abs/2010.07323(odnośnik otworzy się w nowym oknie)) Jiang et al. (2020,
https://arxiv.org/abs/2005.00272(odnośnik otworzy się w nowym oknie)) and Nielsen et al. (2020,
https://arxiv.org/abs/2007.00497(odnośnik otworzy się w nowym oknie)).
An online catalog of planet candidates and their host stars is currently being assembled and will be hosted at the VizieR catalog service. It will combine the scientific output of the transit photometry, asteroseismology and ground-based follow-up (whenever available).
Finally, we carried out a nationwide educational/outreach program as part of a secondment at Ciência Viva, the Portuguese national agency for the promotion of science and technology. The program consisted of a series of Café Scientifique-like events on various topics of modern astrophysics targeting the general public (12 events in total across Portugal).
