We present the discovery of TOI-1420b, an exceptionally low-density (\(\rho = 0.08\pm0.02\) g cm\(^{-3}\)) transiting planet in a \(P = 6.96\) day orbit around a late G dwarf star. Using transit ...observations from TESS, LCOGT, OPM, Whitin, Wendelstein, OAUV, Ca l'Ou, and KeplerCam along with radial velocity observations from HARPS-N and NEID, we find that the planet has a radius of \(R_p\) = 11.9 \(\pm\) 0.3 \(R_\Earth\) and a mass of \(M_p\) = 25.1 \(\pm\) 3.8 \(M_\Earth\). TOI-1420b is the largest-known planet with a mass less than \(50M_\Earth\), indicating that it contains a sizeable envelope of hydrogen and helium. We determine TOI-1420b's envelope mass fraction to be \(f_{env} = 82^{+7}_{-6}\%\), suggesting that runaway gas accretion occurred when its core was at most \(4-5\times\) the mass of the Earth. TOI-1420b is similar to the planet WASP-107b in mass, radius, density, and orbital period, so a comparison of these two systems may help reveal the origins of close-in low-density planets. With an atmospheric scale height of 1950 km, a transmission spectroscopy metric of 580, and a predicted Rossiter-McLaughlin amplitude of about \(17\) m s\(^{-1}\), TOI-1420b is an excellent target for future atmospheric and dynamical characterization.
JWST has ushered in an era of unprecedented ability to characterize exoplanetary atmospheres. While there are over 5,000 confirmed planets, more than 4,000 TESS planet candidates are still ...unconfirmed and many of the best planets for atmospheric characterization may remain to be identified. We present a sample of TESS planets and planet candidates that we identify as "best-in-class" for transmission and emission spectroscopy with JWST. These targets are sorted into bins across equilibrium temperature \(T_{\mathrm{eq}}\) and planetary radius \(R{_\mathrm{p}}\) and are ranked by transmission and emission spectroscopy metric (TSM and ESM, respectively) within each bin. In forming our target sample, we perform cuts for expected signal size and stellar brightness, to remove sub-optimal targets for JWST. Of the 194 targets in the resulting sample, 103 are unconfirmed TESS planet candidates, also known as TESS Objects of Interest (TOIs). We perform vetting and statistical validation analyses on these 103 targets to determine which are likely planets and which are likely false positives, incorporating ground-based follow-up from the TESS Follow-up Observation Program (TFOP) to aid the vetting and validation process. We statistically validate 23 TOIs, marginally validate 33 TOIs to varying levels of confidence, deem 29 TOIs likely false positives, and leave the dispositions for 4 TOIs as inconclusive. 14 of the 103 TOIs were confirmed independently over the course of our analysis. We provide our final best-in-class sample as a community resource for future JWST proposals and observations. We intend for this work to motivate formal confirmation and mass measurements of each validated planet and encourage more detailed analysis of individual targets by the community.
We present the discovery of TOI-3235 b, a short-period Jupiter orbiting an M-dwarf with a stellar mass close to the critical mass at which stars transition from partially to fully convective. ...TOI-3235 b was first identified as a candidate from TESS photometry, and confirmed with radial velocities from ESPRESSO, and ground-based photometry from HATSouth, MEarth-South, TRAPPIST-South, LCOGT, and ExTrA. We find that the planet has a mass of \(\mathrm{0.665\pm0.025\,M_J}\) and a radius of \(\mathrm{1.017\pm0.044\,R_J}\). It orbits close to its host star, with an orbital period of \(\mathrm{2.5926\,d}\), but has an equilibrium temperature of \(\mathrm{\approx 604 \, K}\), well below the expected threshold for radius inflation of hot Jupiters. The host star has a mass of \(\mathrm{0.3939\pm0.0030\,M_\odot}\), a radius of \(\mathrm{0.3697\pm0.0018\,R_\odot}\), an effective temperature of \(\mathrm{3389 \, K}\), and a J-band magnitude of \(\mathrm{11.706\pm0.025}\). Current planet formation models do not predict the existence of gas giants such as TOI-3235 b around such low-mass stars. With a high transmission spectroscopy metric, TOI-3235 b is one of the best-suited giants orbiting M-dwarfs for atmospheric characterization.
Hot jupiters (P < 10 d, M > 60 \(\mathrm{M}_\oplus\)) are almost always found alone around their stars, but four out of hundreds known have inner companion planets. These rare companions allow us to ...constrain the hot jupiter's formation history by ruling out high-eccentricity tidal migration. Less is known about inner companions to hot Saturn-mass planets. We report here the discovery of the TOI-2000 system, which features a hot Saturn-mass planet with a smaller inner companion. The mini-neptune TOI-2000 b (\(2.70 \pm 0.15 \,\mathrm{R}_\oplus\), \(11.0 \pm 2.4 \,\mathrm{M}_\oplus\)) is in a 3.10-day orbit, and the hot saturn TOI-2000 c (\(8.14^{+0.31}_{-0.30} \,\mathrm{R}_\oplus\), \(81.7^{+4.7}_{-4.6} \,\mathrm{M}_\oplus\)) is in a 9.13-day orbit. Both planets transit their host star TOI-2000 (TIC 371188886, V = 10.98, TESS magnitude = 10.36), a metal-rich (Fe/H = \(0.439^{+0.041}_{-0.043}\)) G dwarf 174 pc away. TESS observed the two planets in sectors 9-11 and 36-38, and we followed up with ground-based photometry, spectroscopy, and speckle imaging. Radial velocities from CHIRON, FEROS, and HARPS allowed us to confirm both planets by direct mass measurement. In addition, we demonstrate constraining planetary and stellar parameters with MIST stellar evolutionary tracks through Hamiltonian Monte Carlo under the PyMC framework, achieving higher sampling efficiency and shorter run time compared to traditional Markov chain Monte Carlo. Having the brightest host star in the V band among similar systems, TOI-2000 b and c are superb candidates for atmospheric characterization by the JWST, which can potentially distinguish whether they formed together or TOI-2000 c swept along material during migration to form TOI-2000 b.
NASA's Transiting Exoplanet Survey Satellite (TESS) is an all-sky survey mission designed to find transiting exoplanets orbiting nearby bright stars. It has identified more than 329 transiting ...exoplanets, and almost 6,000 candidates remain unvalidated. In this manuscript, we discuss the findings from the ongoing VaTEST (Validation of Transiting Exoplanets using Statistical Tools) project, which aims to validate new exoplanets for further characterization. We validated 11 new exoplanets by examining the light curves of 24 candidates using the LATTE and TESS-Plot tools and computing the False Positive Probabilities using the statistical validation tool TRICERATOPS. These include planets suitable for atmospheric characterization using transmission spectroscopy (TOI-2194b), emission spectroscopy (TOI-3082b and TOI-5704b) and for both transmission and emission spectroscopy (TOI-672b, TOI- 1694b, and TOI-2443b); One super-Earth (TOI-2194b) orbiting a bright (V = 8.42 mag), metal-poor (Fe/H = -0.3720 \(\pm\) 0.1) star; one short-period Neptune-like planet (TOI-5704) in the Hot Neptune Desert. In total, we validated 1 super-Earth, 7 sub-Neptunes, 1 Neptune-like, and 2 sub-Saturn or super-Neptune-like exoplanets. Additionally, we identify five likely planet candidates (TOI-323, TOI- 1180, TOI-2200, TOI-2408 and TOI-3913) which can be further studied to establish their planetary nature.
We present the discovery and confirmation of a transiting hot, bloated Super-Neptune using photometry from TESS and LCOGT and radial velocity measurements from HARPS. The host star TOI-2498 is a V = ...11.2, G-type (T\(_{eff}\) = 5905 \(\pm\) 12K) solar-like star with a mass of 1.12 \(\pm\) 0.02 M\(_{\odot}\) and a radius of 1.26 \(\pm\) 0.04 R\(_{\odot}\). The planet, TOI-2498 b, orbits the star with a period of 3.7 days, has a radius of 6.1 \(\pm\) 0.3 R\(_{\oplus}\), and a mass of 35 \(\pm\) 4 M\(_{\oplus}\). This results in a density of 0.86 \(\pm\) 0.25 g cm\(^{-3}\). TOI-2498 b resides on the edge of the Neptune desert; a region of mass-period parameter space in which there appears to be a dearth of planets. Therefore TOI-2498 b is an interesting case to study to further understand the origins and boundaries of the Neptune desert. Through modelling the evaporation history, we determine that over its \(\sim\)3.6 Gyr lifespan, TOI-2498 b has likely reduced from a Saturn sized planet to its current radius through photoevaporation. Moreover, TOI-2498 b is a potential candidate for future atmospheric studies searching for species like water or sodium in the optical using high-resolution, and for carbon based molecules in the infra-red using JWST.
A new generation of observatories is enabling detailed study of exoplanetary atmospheres and the diversity of alien climates, allowing us to seek evidence for extraterrestrial biological and ...geological processes. Now is therefore the time to identify the most unique planets to be characterised with these instruments. In this context, we report on the discovery and validation of TOI-715 b, a \(R_{\rm b}=1.55\pm 0.06\rm R_{\oplus}\) planet orbiting its nearby (\(42\) pc) M4 host (TOI-715/TIC 271971130) with a period \(P_{\rm b} = 19.288004_{-0.000024}^{+0.000027}\) days. TOI-715 b was first identified by TESS and validated using ground-based photometry, high-resolution imaging and statistical validation. The planet's orbital period combined with the stellar effective temperature \(T_{\rm eff}=3075\pm75~\rm K\) give this planet an instellation \(S_{\rm b} = 0.67_{-0.20}^{+0.15}~\rm S_\oplus\), placing it within the most conservative definitions of the habitable zone for rocky planets. TOI-715 b's radius falls exactly between two measured locations of the M-dwarf radius valley; characterising its mass and composition will help understand the true nature of the radius valley for low-mass stars. We demonstrate TOI-715 b is amenable for characterisation using precise radial velocities and transmission spectroscopy. Additionally, we reveal a second candidate planet in the system, TIC 271971130.02, with a potential orbital period of \(P_{02} = 25.60712_{-0.00036}^{+0.00031}\) days and a radius of \(R_{02} = 1.066\pm0.092\,\rm R_{\oplus}\), just inside the outer boundary of the habitable zone, and near a 4:3 orbital period commensurability. Should this second planet be confirmed, it would represent the smallest habitable zone planet discovered by TESS to date.
We report the discovery of 1SWASP J022916.91-395901.4 = GSC 07552-00389, a possible new VY Sculptoris variable in Eridanus, which is associated with the X-ray source 1RXS J022917.1-395851.
We present the discovery and characterization of HIP 33609 b, a transiting warm brown dwarf orbiting a late B star, discovered by NASA's Transiting Exoplanet Survey Satellite TESS as TOI-588 b. HIP ...33609 b is a large (R\(_{b}\) = 1.580\(_{-0.070}^{+0.074}\) R\(_{J}\)) brown dwarf on a highly eccentric (e = 0.560\(_{-0.031}^{+0.029}\)) orbit with a 39-day period. The host star is a bright (V = 7.3 mag), T\(_{eff}\) = 10,400\(_{-660}^{+800}\) K star with a mass of M\(_{*}\) = 2.383\(_{-0.095}^{+0.10}\) M\(_{\odot}\) and radius of R\(_{*}\) = 1.863\(_{-0.082}^{+0.087}\) R\(_{\odot}\), making it the hottest transiting brown dwarf host star discovered to date. We obtained radial velocity measurements from the CHIRON spectrograph confirming the companion's mass of M\(_{b}\) = 68.0\(_{-7.1}^{+7.4}\) M\(_{J}\) as well as the host star's rotation rate (\(vsini_{*} = 55.6 \pm 1.8\) km/s). We also present the discovery of a new comoving group of stars, designated as MELANGE-6, and determine that HIP 33609 is a member. We use a combination of rotation periods and isochrone models fit to the cluster members to estimate an age of 150 \(\pm\) 25 Myr. With a measured mass, radius, and age, HIP 33609 b becomes a benchmark for substellar evolutionary models.
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 <G< 11.8, 7.7 <K< 10.1). Using a combination of time-series photometric and spectroscopic follow-up observations from the TESS Follow-up Observing Program (TFOP) Working Group, we have determined that the planets are Jovian-sized (R\(_{P}\) = 1.00-1.45 R\(_{J}\)), have masses ranging from 0.92 to 5.35 M\(_{J}\), and orbit F, G, and K stars (4753 \(<\) T\(_{eff}\) \(<\) 7360 K). We detect a significant orbital eccentricity for the three longest-period systems in our sample: TOI-2025 b (P = 8.872 days, \(e\) = \(0.220\pm0.053\)), TOI-2145 b (P = 10.261 days, \(e\) = \(0.182^{+0.039}_{-0.049}\)), and TOI-2497 b (P = 10.656 days, \(e\) = \(0.196^{+0.059}_{-0.053}\)). TOI-2145 b and TOI-2497 b both orbit subgiant host stars (3.8 \(<\) \(\log\) g \(<\)4.0), but these planets show no sign of inflation despite very high levels of irradiation. The lack of inflation may be explained by the high mass of the planets; \(5.35^{+0.32}_{-0.35}\) M\(_{\rm J}\) (TOI-2145 b) and \(5.21\pm0.52\) M\(_{\rm J}\) (TOI-2497 b). These six new discoveries contribute to the larger community effort to use {\it TESS} to create a magnitude-complete, self-consistent sample of giant planets with well-determined parameters for future detailed studies.
