Most known planets are found around metal-rich host stars, which has made it difficult to determine whether a lower metallicity limit for planet formation exists and how the properties of planets born in low-metallicity environments may differ from those with metal-rich origins. We present the discovery and characterization of TOI-7169 b (TIC 372048733 b), a hot Jupiter that is orbiting a spectroscopically-confirmed metal-poor ([Fe/H] = -0.72 +/- 0.05) host star. Based on photometry from TESS and follow-up ground-based imaging, we measure an orbital period of 3.4373125 d and a planetary radius of 1.475 +/- 0.029 R_Jup. We use TRES spectroscopy to determine a mass for TOI-7169 b of 0.41 +/- 0.14 M_Jup. The planet is therefore inflated, with a low density of 0.159 +0.055/-0.054 g/cm^3. We also characterize the host star, showing that TOI-7169 is ancient (12.3 +/- 0.6 Gyr) and alpha-enhanced ([alpha/Fe] 0.3), but with a Galactocentric orbit that is confined to the thin disk. TOI-7169 is perhaps the oldest and most metal-poor star currently known to host a transiting giant planet. Future transmission spectroscopy probing the atmosphere of TOI-7169 b may provide insight into the effect of metallicity on the physical properties of giant planets.

Theoretical models predict that subgiants within a narrow mass regime can retain detectable lithium enrichment signatures from planetary engulfment. We test this prediction using TOI-5882, selected because it occupies this favorable subgiant parameter space and hosts a massive brown dwarf (22 MJ, P = 7.1 days) companion capable of dynamically perturbing inner planets. We investigate whether (1) TOI-5882 exhibits lithium enhancement among similar subgiants, (2) planetary material would be deposited in the convective zone, and (3) the required engulfed mass lies within a plausible range for planetary engulfment. Using spectra from the Tillinghast Reflector Echelle Spectrograph, we measured a Li I equivalent width of 75.39 +/- 3.58 m & Aring; and an abundance of A(Li) = 2.49 +/- 0.12 dex. Comparing these values to a control sample of 61 subgiants from the GALactic Archaeology with HERMES (GALAH)DR4 survey, we find that TOI-5882 ranks in the 98.4th percentile in both metrics, confirming significant lithium enrichment. We evaluate the engulfment scenario by modeling convective zone deposition and estimating the mass required to reproduce the observed enhancement relative to the control sample. We perform an estimate of the engulfed planetary mass incorporating CI chondritic Li abundances, as planets formed via core accretion are enriched in heavy elements and lithium partitions with these metals. This yields a required engulfed mass of 9-95 M circle plus-an order of magnitude lower than the 5.6 MJ implied by protosolar assumptions. TOI-5882's lithium excess can plausibly result from the ingestion of a super-Earth to Neptune-mass planet, motivating further studies to test this scenario.

We present the characterization of HIP 61637 b (TOI-5401 b), a brown dwarf discovered by TESS to transit an A-type star. HIP 61637 is the most massive and the brightest star known to host a transiting brown dwarf to date. The companion lies in the middle of the "brown dwarf desert". We perform a joint analysis of light curves from NASA's TESS mission and our high-resolution spectroscopy from the Tillinghast Reflector Echelle Spectrograph. We determine that HIP 61637 b has a radius of R_BD = 1.149^+0.049_-0.038 R_J, a mass of M_BD = 47.8^+1.5_-1.4 M_J, and transits its host star every 6.829104 ± 0.000011 days in a near-circular orbit (e = 0.054 ± 0.013). The host star has a mass of 2.86± 0.12 M_⊙, a radius of 4.33 ± 0.17 R_⊙, and an effective temperature of T_eff = 9180^+240_-230 K. We find that the host is nearing the end of its time on the main sequence and has begun to evolve, allowing for a precise age estimation of 396 ± 46 Myr for the system using stellar evolution models. This adds an important data point to the handful of well-characterized transiting brown dwarfs with reliable age estimates, allowing us to test the latest substellar evolution models. Theory of tidal evolution predicts that tidal dissipation mechanisms have circularized the orbit, consistent with the observed near-zero eccentricity.

We present the discovery of 30 transiting giant planets that were initially detected using data from NASA's Transiting Exoplanet Survey Satellite mission. These new planets orbit relatively bright (G <= 12.5) FGK host stars with orbital periods between 1.6 and 8.2 days, and have radii between 0.9 and 1.7 Jupiter radii. We performed follow-up ground-based photometry, high angular resolution imaging, high-resolution spectroscopy, and radial velocity monitoring for each of these objects to confirm that they are planets and determine their masses and other system parameters. The planets' masses span more than an order of magnitude (0.17 M-J < M-p < 3.3 M-J). For two planets, TOI-3593 b and TOI-4961 b, we measured significant nonzero eccentricities of 0.11(-0.03)(+0.05) and 0.18(-0.05)(+0.04 ), respectively, while for the other planets, the data typically provide a 1 sigma upper bound of 0.15 on the eccentricity. These discoveries represent a major step toward assembling a complete, magnitude-limited sample of transiting hot Jupiters around FGK stars.

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 present the discovery and characterization of TOI-4364b, a young mini-Neptune in the tidal tails of the Hyades cluster, identified through TESS transit observations and ground-based follow-up photometry. The planet orbits a bright M dwarf (K = 9.1 mag) at a distance of 44 pc, with an orbital period of 5.42 days and an equilibrium temperature of 488-7+9 K. The host star's well-constrained age of 710 Myr makes TOI-4364b an exceptional target for studying early planetary evolution around low-mass stars. We determined a planetary radius of 2.01-0.08+0.10R circle plus , indicating that this planet is situated near the upper edge of the radius valley. This suggests that the planet retains a modest H/He envelope. As a result, TOI-4364b provides a unique opportunity to explore the transition between rocky super-Earths and gas-rich mini-Neptunes at the early stages of evolution. Its radius, which may still evolve as a result of ongoing atmospheric cooling, contraction, and photoevaporation, further enhances its significance for understanding planetary development. Furthermore, TOI-4364b's moderately high transmission spectroscopy metric of 44.2 positions it as a viable candidate for atmospheric characterization with instruments such as JWST. This target has the potential to offer crucial insights into atmospheric retention and loss in young planetary systems.

Although hot Jupiters were the first exoplanets discovered orbiting main-sequence stars, the dominant mechanisms through which they form and evolve are not known. To address the questions surrounding their origins, the Migration and Evolution of giant ExoPlanets (MEEP) survey aims to create a complete, magnitude-limited ( G < 12.5) sample of hot Jupiters that can be used to constrain the frequency of different migration pathways. NASA's Transiting Exoplanet Survey Satellite provides the unique combination of sky coverage and photometric precision to achieve this goal, which will likely be a key result of the mission. In this second installment of the MEEP survey, we re-analyse one benchmark hot Jupiter system, TOI-4138, and discover four additional super-Jupiters which are each more than five times as massive as Jupiter: TOI-4773 b, TOI-5261 b, TOI-5350 b, and TOI-6420 b. One of these planets, TOI-5261 b, is 11.49 times the mass of Jupiter, nearly massive enough to ignite deuterium fusion, and has an eccentric ( e = 0 . 1585) orbit. TOI-4138, TOI-4773, TOI-5350, and TOI-6420 each have lithium absorption features in their spectra. TOI-4138 is an F-type subgiant with a lithium equivalent width of 120 . +/- 13 m & Aring;, which is similar to 4.5cr larger than the median lithium equivalent width of a control sample of 1381 similar stars, making TOI-4138 a compelling candidate for planetary engulfment.

We present the discovery of 11 new transiting brown dwarfs and low-mass M-dwarfs from NASA's TESS mission: TOI-2844, TOI-3122, TOI-3577, TOI-3755, TOI-4462, TOI-4635, TOI-4737, TOI-4759, TOI-5240, TOI-5467, and TOI-5882. They consist of 5 brown dwarf companions and 6 very low mass stellar companions ranging in mass from 25 M_ J to 128 M_ J. We used a combination of photometric time-series, spectroscopic, and high resolution imaging follow-up as a part of the TESS Follow-up Observing Program (TFOP) in order to characterize each system. With over 50 transiting brown dwarfs confirmed, we now have a large enough sample to directly test different formation and evolutionary scenarios. We provide a renewed perspective on the transiting brown dwarf desert and its role in differentiating between planetary and stellar formation mechanisms. Our analysis of the eccentricity distribution for the transiting brown dwarf sample does not support previous claims of a transition between planetary and stellar formation at ∼42 M_ J. We also contribute a first look into the metallicity distribution of transiting companions in the range 7 - 150 M_ J, showing that this too does not support a ∼42 M_ J transition. Finally, we also detect a significant lithium absorption feature in one of the brown dwarf hosts (TOI-5882) but determine that the host star is likely old based on rotation, kinematic, and photometric measurements. We therefore claim that TOI-5882 may be a candidate for planetary engulfment.

We present the discovery of 11 new transiting brown dwarfs (BDs) and low-mass M dwarfs from NASA’s Transiting Exoplanet Survey Satellite (TESS) mission: TOI-2844, TOI-3122, TOI-3577, TOI-3755, TOI-4462, TOI-4635, TOI-4737, TOI-4759, TOI-5240, TOI-5467, and TOI-5882. They consist of five BD companions and six very-low-mass stellar companions ranging in mass from 25 M _J to 128 M _J . We used a combination of photometric time-series, spectroscopic, and high-resolution imaging follow-up as a part of the TESS Follow-up Observing Program (or TFOP) to characterize each system. With over 50 transiting BDs confirmed, we now have a large enough sample to directly test different formation and evolutionary scenarios. We provide a renewed perspective on the transiting “brown dwarf desert” and its role in differentiating between planetary and stellar formation mechanisms. Our analysis of the eccentricity distribution for the transiting BD sample does not support previous claims of a transition between planetary and stellar formation at ∼42 M _J . We also contribute a first look into the metallicity distribution of transiting companions in the range 7–150 M _J , showing that this does not support a ∼42 M _J transition too. Finally, we also detect a significant lithium absorption feature in one of the BD hosts (TOI-5882). However, we determine that the host star is likely old based on rotation, kinematic, and photometric mdeasurements. We therefore claim that TOI-5882 may be a candidate for planetary engulfment.

Hot Jupiters were many of the first exoplanets discovered in the 1990s, but in the decades since their discovery the mysteries surrounding their origins have remained. Here we present nine new hot Jupiters (TOI-1855 b, TOI-2107 b, TOI-2368 b, TOI-3321 b, TOI-3894 b, TOI-3919 b, TOI-4153 b, TOI-5232 b, and TOI-5301 b) discovered by NASA's TESS mission and confirmed using ground-based imaging and spectroscopy. These discoveries are the first in a series of papers named the Migration and Evolution of giant ExoPlanets survey and are part of an ongoing effort to build a complete sample of hot Jupiters orbiting FGK stars, with a limiting Gaia G-band magnitude of 12.5. This effort aims to use homogeneous detection and analysis techniques to generate a set of precisely measured stellar and planetary properties that is ripe for statistical analysis. The nine planets presented in this work occupy a range of masses (0.55M(J) < M-P < 3.88M(J)) and sizes (0.967R(J )< R-P < 1.438R(J)) and orbit stars that have an effective temperature in the range of 5360 K < T-eff < 6860 K with Gaia G-band magnitudes ranging from 11.1 to 12.7. Two of the planets in our sample have detectable orbital eccentricity: TOI-3919 b (e=0.259(-0.036)(+0.033)) and TOI-5301 b ( e=0.33(-0.10)(+0.11)). These eccentric planets join a growing sample of eccentric hot Jupiters that are consistent with high-eccentricity tidal migration, one of the three most prominent theories explaining hot Jupiter formation and evolution.

We present the discovery and characterization of six short-period, transiting giant planets from NASA's Transiting Exoplanet Survey Satellite (TESS) -- TOI-1811 (TIC 376524552), TOI-2025 (TIC 394050135), TOI-2145 (TIC 88992642), TOI-2152 (TIC 395393265), TOI-2154 (TIC 428787891), & TOI-2497 (TIC 97568467). All six planets orbit bright host stars (8.9

We report the discovery of TOI-700 e, a 0.95 R _⊕ planet residing in the Optimistic Habitable Zone (HZ) of its host star. This discovery was enabled by multiple years of monitoring from NASA’s Transiting Exoplanet Survey Satellite (TESS) mission. The host star, TOI-700 (TIC 150428135), is a nearby (31.1 pc), inactive, M2.5 dwarf ( V _mag = 13.15). TOI-700 is already known to host three planets, including the small, HZ planet, TOI-700 d. The new planet has an orbital period of 27.8 days, and based on its radius (0.95 R _⊕ ), it is likely rocky. TOI-700 was observed for 21 sectors over Years 1 and 3 of the TESS mission, including 10 sectors at 20 s cadence in Year 3. Using this full set of TESS data and additional follow-up observations, we identify, validate, and characterize TOI-700 e. This discovery adds another world to the short list of small, HZ planets transiting nearby and bright host stars. Such systems, where the stars are bright enough that follow-up observations are possible to constrain planet masses and atmospheres using current and future facilities, are incredibly valuable. The presence of multiple small, HZ planets makes this system even more enticing for follow-up observations.

While secondary mass inferences based on single-lined spectroscopic binary (SB1) solutions are subject to sin i degeneracies, this degeneracy can be lifted through the observations of eclipses. We combine the subset of Gaia Data Release 3 SB1 solutions consistent with brown dwarf-mass secondaries with the Transiting Exoplanet Survey Satellite (TESS) Object of Interest (TOI) list to identify three candidate transiting brown dwarf systems. Ground-based precision radial velocity follow-up observations confirm that TOI-2533.01 is a transiting brown dwarf with M = 72 − 3 + 3 M Jup = 0.069 − 0.003 + 0.003 M ⊙ orbiting TYC 2010-124-1 and that TOI-5427.01 is a transiting very low-mass star with M = 93 − 2 + 2 M Jup = 0.088 − 0.002 + 0.002 M ⊙ orbiting UCAC4 515-012898. We validate TOI-1712.01 as a very low-mass star with M = 82 − 7 + 7 M Jup = 0.079 − 0.007 + 0.007 M ⊙ transiting the primary in the hierarchical triple system BD+45 1593. Even after accounting for third light, TOI-1712.01 has a radius nearly a factor of 2 larger than predicted for isolated stars with similar properties. We propose that the intense instellation experienced by TOI-1712.01 diminishes the temperature gradient near its surface, suppresses convection, and leads to its inflated radius. Our analyses verify Gaia DR3 SB1 solutions in the low Doppler semiamplitude limit, thereby providing the foundation for future joint analyses of Gaia radial velocities and Kepler, K2, TESS, and PLAnetary Transits and Oscillations light curves for the characterization of transiting massive brown dwarfs and very low-mass stars.

ABSTRACT We report the discovery of TOI-2119b, a transiting brown dwarf (BD) that orbits and is completely eclipsed by an active M-dwarf star. Using light-curve data from the Transiting Exoplanet Survey Satellite mission and follow-up high-resolution Doppler spectroscopic observations, we find the BD has a radius of Rb = 1.08 ± 0.03RJ, a mass of Mb = 64.4 ± 2.3MJ, an orbital period of P = 7.200865 ± 0.00002 d, and an eccentricity of e = 0.337 ± 0.002. The host star has a mass of M⋆ = 0.53 ± 0.02M⊙, a radius of R⋆ = 0.50 ± 0.01R⊙, an effective temperature of Teff = 3621 ± 48K, and a metallicity of $\rm [Fe/H]=+0.06\pm 0.08$. TOI-2119b joins an emerging population of transiting BDs around M-dwarf host stars, with TOI-2119 being the ninth such system. These M-dwarf–brown dwarf systems typically occupy mass ratios near q = Mb/M⋆ ≈ 0.1−0.2, which separates them from the typical mass ratios for systems with transiting substellar objects and giant exoplanets that orbit more massive stars. The nature of the secondary eclipse of the BD by the star enables us to estimate the effective temperature of the substellar object to be 2030 ± 84K, which is consistent with predictions by substellar evolutionary models.

Introduction: Our Sun was likely born as a protostar in a dense star forming region, in the vicinity of several massive (>8 M) stars. Very early in its history, the protoplanetary disk around the proto-Sun was impacted by debris from the supernova (SN) explosions of some of these massive stars. This caused an enrichment of the disk with short-lived radionuclides, the daughter products of which we observe in meteorites today. Injection of r-process nuclides resulting from SN events led to observed excesses of Cr, Ti, and r-process Mo in calciumaluminum-rich inclusions (CAIs) [1−3]. In one scenario that can explain these r-process enrichments, these earliest solids derived their compositions from infalling material from a heterogenous molecular cloud, followed by inward transport to the inner disk, where CAIs condensed [4]. In addition, it is often surmised that the onset of our solar system was triggered by such an event [e.g., 5]. In this study, we investigate whether SN ejecta are intrinsically heterogeneous in r-process nuclides (Cr and Ti), and whether it is possible to inject r-process nuclides alone into a young protoplanetary disk. We also explore the chemistry and timeline by which rprocess nuclides mix and pollute the protoplanetary disk, and compare it to the accreted s-process nuclides. Finally, we compare the known Cr and Ti isotopic compositions of stardust in meteorites to the ejecta compositions in core collapse supernova (CCSN). Methods: The CCSN nucleosynthetic yields were determined by a 3D, spherically symmetric, CCSN simulation introduced in [6,7]. This model, called 15S, is based on a 15 M progenitor star which is evolved using the 1D stellar evolution code TYCHO [8]. After core collapse and shock revival, the star is mapped into the 3D smoothed-particle hydrodynamics (SPH) code SNSPH [9,10] for 43 simulated hours until it is postprocessed and isotope yields are captured using the Burnf code [11]. To avoid isotope abundances being influenced by rounding errors, only isotope mass fractions higher than 10 (relative to the mass of each of the roughly 1 million SPH particles) are included. Maps of the SN ejecta were created using the SPH visualization software SPLASH [12] and plots were created in MATLAB. To ensure that the interior of the explosion can be investigated, cross-sections were formed which have a width of approximately 4.5 au in the Y direction. Additionally, SPH particles in the hydrogen envelope contain neither Ti nor Cr, we consider only the inner 6 au of the supernova ejecta. Results and Discussion: Stardust enriched in rprocess nuclides. Oxide stardust <100 nm in size shows large excesses in Cr and Ti [13−15]. The reported δCr values of SiC stardust in acid leachates, on the other hand, tend to be indistinguishable from the terrestrial values within the experimental uncertainties [16], although Ti excesses have been observed [17,18]. Marhas et al. [19] reported 300-600 ‰ Cr excess in one unique SiC X grain. Graphite stardust exhibits large enrichments of Ti [20], although Cr isotopes have not been explored. Figure 1. Comparison of observed Cr and Ti isotope ratios in oxide stardust with isotopic compositions predicted by 3D CCSN model 15S. The excellent correlation makes CCSN potential sources of such stardust grains.

We present the isotope yields of two post-explosion, three-dimensional 15 core-collapse supernova models, 15S and 15A, and compare them to the carbon, nitrogen, silicon, aluminum, sulfur, calcium, titanium, iron, and nickel isotopic compositions of SiC stardust. We find that these core-collapse supernova models predict similar carbon and nitrogen compositions to SiC X grains and grains with 12C/13C < 20 and 14N/15N < 60, which we will hereafter refer to as SiC ‘D’ grains. Material from the interior of a 15 explosion reaches high enough temperatures shortly after core collapse to produce the large enrichments of 13C and 15N necessary to replicate the compositions of SiC D grains. The innermost ejecta in a core-collapse supernova is operating in the neutrino-driven regime and undergoes fast proton capture after being heated by the supernova shockwave. Both 3D models predict 0.3 Al/27Al < 1.5, comparable to the ratios seen in SiC X, C, and D grains. Models 15S and 15A, in general, predict very large anomalies in calcium isotopes but do compare qualitatively with the SiC X grain measurements that show 44Ca and 43Ca excesses. The titanium isotopic compositions of SiC X grains are well reproduced. The models predict 57Fe excesses and depletions that are observed in SiC X grains, and in addition predict accurately the 60Ni/58Ni, 61Ni/58Ni, and 62Ni/58Ni ratios in SiC X grains, as a result of fast neutron captures initiated by the propagation of the supernova shockwave. Finally, symmetry has a noticeable effect on the production of silicon, sulfur, and iron isotopes in the SN ejecta.

Introduction: One-dimensional supernova (SN) models have been used successfully to explain the composition of presolar SiC X grains with 12C/13C ratios > 20, low 14N/15N ratios (< 272), 28Si excesses with respect to solar (up to ~800 ‰), and large 26Al/27Al ratios (> 10-2) [e.g., 1]. These grains usually exhibit 57Fe excesses [2], while some show ~400 ‰ depletions in 57Fe. In these models [e.g., 35], an ad-hoc mixing of the zones in a 1020 M⊙ pre-supernova star match several isotope ratios of the presolar grains simultaneously, which has been used to confirm their supernova origins. However, spatially resolved SN remnants and multi-dimensional SN models have shown little evidence for such large-scale mixing. Furthermore, the inability to model certain physical processes (e.g., turbulence, instabilities, convection) [6] accurately in these one-dimensional models cannot be ignored. Finally, important qualities such as symmetry need to be considered because varying expansion velocities and shock heating in asymmetric supernovae (SNe) produce noticeably different isotope abundances compared to similar symmetric SNe. In this work, we present for the first time a comparison of presolar SiC grain data to four threedimensional SN models of varying masses and symmetries. We focused on the major isotope systems of C, N, Si, Al, Fe, and Ni. Our work also intends to provide insights into the origin of grains with very low 12C/13C ratios (< 100), some of which arguably have nova origins [79], and SiC C grains, typically identified with large 29,30Si enrichments [10,11]. Methods: We explored both the pre-explosion and post-explosion data from a 20 M⊙ SN and three 15 M⊙ models. The pre-explosion SN models are divided into three-dimensional spatial zones of mass 1027 g to 1032 g using Lagrangian mass coordinates. The post-explosion SN models were created using smoothed particle hydrodynamics, as described by [12]. In this work, we refer to the “particles” generated by the models as clumps, with each clump having a mass of approximately 5 × 10-6 M⊙ (1.7 M⊕). The first model is g292-j4c, a 20 M⊙ progenitor with 2:1 velocity asymmetry between the poles and the equator. The other models are 50Am, a spherically symmetric 15 M⊙ explosion, jet3b, an asymmetric 15 M⊙ explosion, and cco2, a 15 M⊙ explosion with a 1.35 M⊙ central compact object (CCO) that is free to accrete momentum for infalling material. 50Am and jet3b were used to find differences between the isotopes ejected from asymmetric and symmetric SNe. The 20 M⊙ model, g292j4c, was used to investigate the differences in C and N compositions in clumps ejected from a higher-mass asymmetric SN. Finally, cco2 was used to explore the effects of deep convective overturn driven by the engine, motion of the CCO, or progenitor asymmetries on the isotopic signatures of SN ejecta. The pre-explosion and post-explosion model data was processed using code written in MATLAB. The visualization tool SPLASH was used to generate isotope abundance maps of the post-explosion models. Presolar grain data was taken from the presolar grain database [13], as well as literature sources [e.g., 2, 14]. Results and Discussion: SiC X Grains. We found that the model g292-j4c produced 5751 clumps during post-explosion (0.6% of the full dataset) with similar carbon and nitrogen compositions to X grains (Figure 1). Substantial amounts of 15N were also produced in the remaining models, 50Am, jet3b, and cco2, but these had higher 12C/13C ratios (4.5×103 – 6.6×104) than g292-j4c in most cases. All four models had clumps with large 28Si excesses as well as clumps with large 29,30Si excesses (Figure 2). Overall, g292-j4c explains the C, N and Si isotope systematics better than the symmetric and asymmetric 15 M⊙ models. As discussed below, the low 12C/13C ratios observed in some X grains can be explained by the pre-SN material in the same model g292-j4c.