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Although not predicted by standard stellar evolution, the surface abundance of light elements, such as lithium (Li), carbon, and nitrogen, changes during the red giant branch (RGB) as a result of extra-mixing. This is associated usually with thermohaline mixing acting after the RGB bump. Peculiar Li-enriched RGB stars might also be related to either enhanced extra-mixing or pollution from external sources. We measure the Li abundance and carbon isotopic ratio 12C/13C in a sample of 166 field red giants with -0.3<[Fe/H]<0.2, targeted by the EXPRESS radial velocity program to analyze the effects of extra-mixing. Multiple-epoch observations needed for exoplanet detection are used to decrease the effects of telluric contamination in 12C/13C measurements. Due to the prevalence of upper limits, the Li abundance pattern is complicated to interpret, but the comparison between RGB and core-He burning giants shows effects of extra-mixing consistent with thermohaline. The most Li-enriched giant in the sample, classified as a RGB star close to the RGB bump, has low 12C/13C. Given that the 12C/13C should not be affected by planet engulfment, this does not seem to be the source of the high Li. There is a decreasing correlation between mass and 12C/13C in the RGB and an increasing correlation in the horizontal branch, which, once again, is consistent with thermohaline mixing. Our data also shows a correlation between 12C/13C and [Fe/H]. There is no evident impact of binarity either on Li or on 12C/13C. Our sample shows behavior consistent with additional mixing acting after the RGB bump. The 12C/13C adds new clues to describe extra-mixing, and could well be the best tool to study mixing in red giants. Additional measurements of 12C/13C in field stars would greatly improve our ability to compare with models and understand mixing mechanisms.

RV surveys of evolved stars allow us to probe a higher stellar mass range compared to main-sequence samples. Differences between the planet populations can be caused by either the differing stellar mass or stellar evolution. To properly disentangle the effects of both, the planet population around giant stars needs to be characterized as accurately as possible. Our goal is to investigate the giant planet occurrence rate around evolved stars and determine its dependence on stellar mass, metallicity, and orbital period. We combine data from the Lick, EXPRESS, and PPPS giant star surveys, yielding a sample of 482 evolved stars and 37 planets. We homogeneously rederived the stellar parameters and accounted for varying observational coverage, precision, and stellar noise properties by computing detection maps via injection and retrieval of synthetic planetary signals. We then computed occurrence rates as a function of period, stellar mass, and metallicity, corrected for incompleteness. Our findings agree with previous studies that found a positive planet-metallicity correlation for evolved stars and identified a peak in the occurrence rate as a function of stellar mass, but our results place it at a slightly smaller mass of 1.68Msun. The period dependence of the occurrence rate seems to follow a broken power-law or log-normal peaking at 700-800 days, roughly corresponding to 1.6AU for a 1Msun star and 2.0AU for a 2Msun star. This peak could be a remnant from halted migration around intermediate-mass stars, caused by stellar evolution, or an artifact from contamination by false positives. The global occurrence rate of giant planetary systems is 10.7% for the entire sample, while the subsets of RGB and HB stars exhibit 14.2% and 6.6%, respectively. However, we demonstrate that the different stellar mass distributions suffice to explain the apparent change of occurrence with evolutionary stage.

We report the discovery and characterisation of three transiting warm Jupiters: TIC 147027702b, TIC 245076932b and TIC 87422071b. These systems were initially identified as transiting candidates using light curves generated from the full-frame images of the TESS mission. We confirmed the planetary nature of these objects with ground-based spectroscopic follow-up observations using FEROS and the new PLATOSpec spectrograph attached to the ESO 1.52 m telescope at the La Silla Observatory, and with ground-based photometric observations of the Observatoire Moana, Las Cumbres Observatory Global Telescope and ASTEP. From a global fit to the photometry and radial velocities, we determine that the planet TIC 147027702b has a low-eccentric orbit (\\(e = 0.13 \\pm 0.05\\)) with a period of 44.4 days and has a mass of \\(1.09^{+0.07}_{-0.13}\\) M\\(_J\\) and a radius of \\(0.98 \\pm 0.06\\) R\\(_J\\). TIC 245076932b has a moderately low mass of \\(0.51 \\pm 0.05\\) M\\(_J\\), a radius of \\(0.97 \\pm 0.05\\) R\\(_J\\), and an eccentric orbit (\\(e = 0.43 \\pm 0.02\\)) with a period of 21.6 days. TIC 87422071b has a mass of \\(1.29 \\pm 0.10\\) M\\(_J\\), a radius of \\(0.97 \\pm 0.08\\) R\\(_J\\), and has a slightly eccentric orbit (\\(e = 0.12 \\pm 0.07\\)) with a period of 11.3 days. These well-characterised warm Jupiters expand the currently limited sample of similar gas giants and provide valuable benchmarks for testing models of giant-planet formation, migration, and tidal evolution.

We report the discovery of TOI-4507 b, a transiting sub-Saturn with a density \\(<\\) 0.2 g/cm\\(^3\\) on a 105-day prograde orbit around a 700 Myr old F star. The transits were detected using data from TESS as well as the Antarctic telescope ASTEP. A joint analysis of the light curves and radial velocities from HARPS, FEROS, and CORALIE confirmed the planetary nature of the signal by limiting the mass to be below 20 \\(M_\\oplus\\) at 95% confidence. The radial velocities also exhibit the Rossiter-McLaughlin effect and imply that the planet orbits the star in a prograde orbit with a sky-projected obliquity \\(\\lambda=-15_{-44}^{+50}\\) deg (\\(|\\lambda|<80\\) deg at \\(3\\sigma\\)). With these characteristics, TOI-4507 is one of the longest-period systems for which the stellar obliquity has been measured, and the planet is among the longest-period and youngest ''super-puff'' planets yet discovered.

We present a joint analysis of TTVs and Doppler data for the transiting exoplanet system TOI-4504. TOI-4504 c is a warm Jupiter-mass planet that exhibits the largest known transit timing variations (TTVs), with a peak-to-node amplitude of \\(\\sim\\) 2 days, the largest value ever observed, and a super-period of \\(\\sim\\) 930 d. TOI-4504 b and c were identified in public TESS data, while the TTVs observed in TOI-4504 c, together with radial velocity (RV) data collected with FEROS, allowed us to uncover a third, non-transiting planet in this system, TOI-4504 d. We were able to detect transits of TOI-4504 b in the TESS data with a period of 2.4261\\(\\pm 0.0001\\) days and derive a radius of 2.69\\(\\pm 0.19\\) R\\(_{\\oplus}\\). The RV scatter of TOI-4504 was too large to constrain the mass of TOI-4504 b, but the RV signals of TOI-4504 c \\& d were sufficiently large to measure their masses. The TTV+RV dynamical model we apply confirms TOI-4504 c as a warm Jupiter planet with an osculating period of 82.54\\(\\pm 0.02\\) d, mass of 3.77\\(\\pm 0.18\\) M\\(_{\\rm J}\\) and a radius of 0.99\\(\\pm 0.05\\) R\\(_{\\rm J}\\), while the non-transiting planet TOI-4504 d, has an orbital period of 40.56\\(\\pm 0.04\\) days and mass of 1.42\\(_{-0.06}^{+0.07}\\) M\\(_{\\rm J}\\). We present the discovery of a system with three exoplanets: a hot sub-Neptune and two warm Jupiter planets. The gas giant pair is stable and likely locked in a first-order 2:1 mean-motion resonance (MMR). The TOI-4504 system is an important addition to MMR pairs, whose increasing occurrence supports a smooth migration into a resonant configuration during the protoplanetary disk phase.

We report the discovery and characterization of TOI-2005b, a warm Jupiter on an eccentric (e~0.59), 17.3-day orbit around a V_mag = 9.867 rapidly rotating F-star. The object was detected as a candidate by TESS and the planetary nature of TOI-2005b was then confirmed via a series of ground-based photometric, spectroscopic, and diffraction-limited imaging observations. The planet was found to reside in a low sky-projected stellar obliquity orbit (lambda = 4.8 degrees) via a transit spectroscopic observation using the Magellan MIKE spectrograph.TOI-2005b is one of a few planets known to have a low-obliquity, high-eccentricity orbit, which may be the result of high-eccentricity coplanar migration. The planet has a periastron equilibrium temperature of ~ 2100 K, similar to some highly irradiated hot Jupiters where atomic metal species have been detected in transmission spectroscopy, and varies by almost 1000 K during its orbit. Future observations of the atmosphere of TOI-2005b can inform us about its radiative timescales thanks to the rapid heating and cooling of the planet.

We investigate the progenitors of long-period hot subdwarf B (sdB) binaries, which form when low-mass red giant branch (RGB) stars lose their envelopes through stable Roche lobe overflow (RLOV) near the tip of the RGB. We aim to expand our previous volume-limited sample of 211 stars within 200 pc to 500 pc and validate it. Additionally, our goal is to provide the distribution of stellar parameters for these stars. We refined the original sample using Gaia DR3 parallaxes and interstellar extinction measurements. High-resolution spectra for 230 stars were obtained between 2019 and 2023 using the CORALIE spectrograph. To confirm or discard binarity, we combined astrometric parameters from Gaia with the resulting radial velocity variations. We derived the distribution of stellar parameters using atmospheric and evolutionary models, confirming that 82% of stars in our sample are indeed RGB stars using the equivalent evolutionary phase. The remaining 18% are red clump (RC) contaminants, which was expected due to the overlapping of RGB and RC stars in the colour-magnitude diagram. Additionally, 75% of the confirmed RGB stars have a high probability of being part of a binary system. Comparison with the literature shows good overall agreement with a scatter \\(\\lesssim 15\\%\\) in stellar parameters, while the masses show somewhat higher dispersion (\\(\\sim 20\\%\\)).

Context. Warm Jupiters are excellent case studies for the investigation of giant planet internal structures and formation theories. However, the sample of long-period transiting giants is still small today for a better understanding of this population. Aims. Starting from a single transit found in the Transiting Exoplanet Survey Satellite (TESS) data, we confirm the planetary nature of the signal and measure its orbital parameters, mass, and radius. We put this system in the context of long-period giant transiting planets and analyzed the viability to sustain atmospheric or dynamical follow-up. Methods. We carried out a spectroscopic follow-up using FEROS and PLATOSpec to obtain precise radial velocities. We added a photometric follow-up with HATPI and Observatoire Moana to obtain a more precise estimate of the orbital period. We derived the orbital and physical parameters through a joint analysis of this data. Results. We report the discovery and characterization of TIC65910228b, a transiting warm Jupiter with a mass of \\(4.554 0.255\\) \\(M_J\\) and a radius of \\(1.088 0.061\\) \\(R_J\\), orbiting an evolved F-type star every \\( 180.52\\) days in an eccentric orbit (\\(e = 0.25 0.04\\)). Conclusions. This planet joins a still under-explored population of long-period (\\(P > 100\\)) massive (\\(M_p > 4\\) \\(M_J\\)) transiting giant planets, being one of the few with a mild eccentricity. This target is a nice example of the potential of single-transit events to populate this region of the parameter space.

While the sample of confirmed exoplanets continues to increase, the population of transiting exoplanets around early-type stars is still limited. These planets allow us to investigate the planet properties and formation pathways over a wide range of stellar masses and study the impact of high irradiation on hot Jupiters orbiting such stars. We report the discovery of TOI-615b, TOI-622b, and TOI-2641b, three Saturn-mass planets transiting main sequence, F-type stars. The planets were identified by the Transiting Exoplanet Survey Satellite (TESS) and confirmed with complementary ground-based and radial velocity observations. TOI-615b is a highly irradiated (\\(\\sim\\)1277 \\(F_{\\oplus}\\)) and bloated Saturn-mass planet (1.69$^{+0.05}_{-0.06}$$R_{Jup}\\( and 0.43\\)^{+0.09}_{-0.08}$$M_{Jup}\\() in a 4.66 day orbit transiting a 6850 K star. TOI-622b has a radius of 0.82\\)^{+0.03}_{-0.03}$$R_{Jup}\\( and a mass of 0.30\\)^{+0.07}_{-0.08}\\(~\\)M_{Jup}\\( in a 6.40 day orbit. Despite its high insolation flux (\\)\\sim\\(600 \\)F_{\\oplus}\\(), TOI-622b does not show any evidence of radius inflation. TOI-2641b is a 0.39\\)^{+0.02}_{-0.04}$$M_{Jup}\\( planet in a 4.88 day orbit with a grazing transit (b = 1.04\\)^{+0.05}_{-0.06 }\\() that results in a poorly constrained radius of 1.61\\)^{+0.46}_{-0.64}$$R_{Jup}\\(. Additionally, TOI-615b is considered attractive for atmospheric studies via transmission spectroscopy with ground-based spectrographs and \\)\\textit{JWST}$. Future atmospheric and spin-orbit alignment observations are essential since they can provide information on the atmospheric composition, formation and migration of exoplanets across various stellar types.

We report the discovery and orbital characterization of three new transiting warm giant planets. These systems were initially identified as presenting single transit events in the light curves generated from the full frame images of the Transiting Exoplanet Survey Satellite (TESS). Follow-up radial velocity measurements and additional light curves were used to determine the orbital periods and confirm the planetary nature of the candidates. The planets orbit slightly metal-rich late F- and early G-type stars. We find that TOI 4406b has a mass of \\(M_P\\)= 0.30 \\(\\pm\\) 0.04 \\(M_J\\) , a radius of \\(R_P\\)= 1.00 \\(\\pm\\) 0.02 \\(R_J\\) , and a low eccentricity orbit (e=0.15 \\(\\pm\\) 0.05) with a period of P= 30.08364 \\(\\pm\\) 0.00005 d . TOI 2338b has a mass of \\(M_P\\)= 5.98 \\(\\pm\\) 0.20 \\(M_J\\) , a radius of \\(R_P\\)= 1.00 \\(\\pm\\) 0.01 \\(R_J\\) , and a highly eccentric orbit (e= 0.676 \\(\\pm\\) 0.002 ) with a period of P= 22.65398 \\(\\pm\\) 0.00002 d . Finally, TOI 2589b has a mass of \\(M_P\\)= 3.50 \\(\\pm\\) 0.10 \\(M_J\\) , a radius of \\(R_P\\)= 1.08 \\(\\pm\\) 0.03 \\(R_J\\) , and an eccentric orbit (e = 0.522 \\(\\pm\\) 0.006 ) with a period of P= 61.6277 \\(\\pm\\) 0.0002 d . TOI 4406b and TOI 2338b are enriched in metals compared to their host stars, while the structure of TOI 2589b is consistent with having similar metal enrichment to its host star.