Studying the relative orientations of the orbits of exoplanets and wide-orbiting binary companions (semimajor axis greater than 100 AU) can shed light on how planets form and evolve in binary ...systems. Previous observations by multiple groups discovered a possible alignment between the orbits of visual binaries and the exoplanets that reside in them. In this study, using data from \textit{Gaia} DR3 and TESS, we confirm the existence of an alignment between the orbits of small planets \((R<6 R_\oplus)\) and binary systems with semimajor axes below 700 AU (\(p=10^{-6}\)). However, we find no statistical evidence for alignment between planet and binary orbits for binary semimajor axes greater than 700 AU, and no evidence for alignment of large, closely-orbiting planets (mostly hot Jupiters) and binaries at any separation. The lack of orbital alignment between our large planet sample and their binary companions appears significantly different from our small planet sample, even taking into account selection effects. Therefore, we conclude that any alignment between wide-binaries and our sample of large planets (predominantly hot Jupiters) is probably not as strong as what we observe for small planets in binaries with semimajor axes less than 700 AU. The difference in the alignment distribution of hot Jupiters and smaller planets may be attributed to the unique evolutionary mechanisms occuring in systems that form hot Jupiters, including potentially destabilizing secular resonances that onset as the protoplanetary disk dissipates and high-eccentricity migration occurring after the disk is gone.
The recent discoveries of Neptune-sized ultra-short period planets (USPs) challenge existing planet formation theories. It is unclear whether these residents of the Hot Neptune Desert have similar ...origins to smaller, rocky USPs, or if this discrete population is evidence of a different formation pathway altogether. We report the discovery of TOI-3261b, an ultra-hot Neptune with an orbital period \(P\) = 0.88 days. The host star is a \(V = 13.2\) magnitude, slightly super-solar metallicity (Fe/H \(\simeq\) 0.15), inactive K1.5 main sequence star at \(d = 300\) pc. Using data from the Transiting Exoplanet Survey Satellite and the Las Cumbres Observatory Global Telescope, we find that TOI-3261b has a radius of \(3.82_{-0.35}^{+0.42}\) \(R_{\oplus}\). Moreover, radial velocities from ESPRESSO and HARPS reveal a mass of \(30.3_{-2.4}^{+2.2}\) \(M_{\oplus}\), more than twice the median mass of Neptune-sized planets on longer orbits. We investigate multiple mechanisms of mass loss that can reproduce the current-day properties of TOI-3261b, simulating the evolution of the planet via tidal stripping and photoevaporation. Thermal evolution models suggest that TOI-3261b should retain an envelope potentially enriched with volatiles constituting \(\sim\)5% of its total mass. This is the second highest envelope mass fraction among ultra-hot Neptunes discovered to date, making TOI-3261b an ideal candidate for atmospheric follow-up observations.
Young terrestrial worlds are critical test beds to constrain prevailing theories of planetary formation and evolution. We present the discovery of HD 63433d - a nearby (22pc), Earth-sized planet ...transiting a young sunlike star (TOI-1726, HD 63433). HD 63433d is the third planet detected in this multiplanet system. The kinematic, rotational, and abundance properties of the host star indicate that it belongs to the young (414 \(\pm\) 23 Myr) Ursa Major moving group, whose membership we update using new data from Gaia DR3 and TESS. Our transit analysis of the TESS light curves indicates that HD 63433 d has a radius of 1.1 \(R_\oplus\) and closely orbits its host star with a period of 4.2 days. To date, HD 63433 d is the smallest confirmed exoplanet with an age less than 500 Myr, and the nearest young Earth-sized planet. Furthermore, the apparent brightness of the stellar host (V \(\approx\) 6.9 mag) makes this transiting multiplanet system favorable to further investigations, including spectroscopic follow-up to probe atmospheric loss in a young Earth-sized world.
We report the discovery of two transiting planets detected by the Transiting Exoplanet Survey Satellite (TESS), TOI-2374 b and TOI-3071 b, orbiting a K5V and an F8V star, respectively, with periods ...of 4.31 and 1.27 days, respectively. We confirm and characterize these two planets with a variety of ground-based and follow-up observations, including photometry, precise radial velocity monitoring and high-resolution imaging. The planetary and orbital parameters were derived from a joint analysis of the radial velocities and photometric data. We found that the two planets have masses of \((57 \pm 4)\) \(M_\oplus\) or \((0.18 \pm 0.01)\) \(M_J\), and \((68 \pm 4)\) \(M_\oplus\) or \((0.21 \pm 0.01)\) \(M_J\), respectively, and they have radii of \((6.8 \pm 0.3)\) \(R_\oplus\) or \((0.61 \pm 0.03)\) \(R_J\) and \((7.2 \pm 0.5)\) \(R_\oplus\) or \((0.64 \pm 0.05)\) \(R_J\), respectively. These parameters correspond to sub-Saturns within the Neptunian desert, both planets being hot and highly irradiated, with \(T_{\rm eq} \approx 745\) \(K\) and \(T_{\rm eq} \approx 1812\) \(K\), respectively, assuming a Bond albedo of 0.5. TOI-3071 b has the hottest equilibrium temperature of all known planets with masses between \(10\) and \(300\) \(M_\oplus\) and radii less than \(1.5\) \(R_J\). By applying gas giant evolution models we found that both planets, especially TOI-3071 b, are very metal-rich. This challenges standard formation models which generally predict lower heavy-element masses for planets with similar characteristics. We studied the evolution of the planets' atmospheres under photoevaporation and concluded that both are stable against evaporation due to their large masses and likely high metallicities in their gaseous envelopes.
We present the confirmation of a hot super-Neptune with an exterior Neptune
companion orbiting a bright (V = 10.1 mag) F-dwarf identified by the
$\textit{Transiting Exoplanet Survey Satellite}$ ...($\textit{TESS}$). The two
planets, observed in sectors 45, 46 and 48 of the $\textit{TESS}$ extended
mission, are $4.74^{+0.16}_{-0.14}$ $R_{\oplus}$ and $3.86^{+0.17}_{-0.16}$
$R_{\oplus}$ with $5.4588385^{+0.0000070}_{-0.0000072}$ d and
$17.8999^{+0.0018}_{-0.0013}$ d orbital periods, respectively. We also obtained
precise space based photometric follow-up of the system with ESAs
$\textit{CHaracterising ExOplanets Satellite}$ ($\textit{CHEOPS}$) to constrain
the radius and ephemeris of TOI-5126 b. TOI 5126 b is located in the "hot
Neptune Desert" and is an ideal candidate for follow-up transmission
spectroscopy due to its high predicted equilibrium temperature ($T_{eq} =
1442^{+46}_{-40}$ K) implying a cloud-free atmosphere. TOI-5126 c is a warm
Neptune ($T_{eq}= 971^{+31}_{-27}$ K) also suitable for follow-up. Tentative
transit timing variations (TTVs) have also been identified in analysis,
suggesting the presence of at least one additional planet, however this signal
may be caused by spot-crossing events, necessitating further precise
photometric follow-up to confirm these signals.
We report the discovery and validation of two long-period giant exoplanets orbiting the early K dwarf TOI-4600 (V=12.6, T=11.9), first detected using observations from the Transiting Exoplanet Survey ...Satellite (TESS) by the TESS Single Transit Planet Candidate Working Group (TSTPC-WG). The inner planet, TOI-4600 b, has a radius of 6.80\(\pm\)0.31 R\(_{\oplus}\) and an orbital period of 82.69 d. The outer planet, TOI-4600 c, has a radius of 9.42\(\pm\)0.42 R\(_{\oplus}\) and an orbital period of 482.82 d, making it the longest-period confirmed or validated planet discovered by TESS to date. We combine TESS photometry and ground-based spectroscopy, photometry, and high-resolution imaging to validate the two planets. With equilibrium temperatures of 347 K and 191 K, respectively, TOI-4600 b and c add to the small but growing population of temperate giant exoplanets that bridge the gap between hot/warm Jupiters and the solar system's gas giants. TOI-4600 is a promising target for further transit and precise RV observations to measure masses and orbits for the planets as well as search for additional non-transiting planets. Additionally, with Transit Spectroscopy Metric (TSM) values of \(\sim\)30, both planets are amenable for atmospheric characterization with JWST. Altogether will lend insight into the formation and evolution of planet systems with multiple giant exoplanets.
We report the discovery of three transiting low-mass companions to aged stars: a brown dwarf (TOI-2336b) and two objects near the hydrogen burning mass limit (TOI-1608b and TOI-2521b). These three ...systems were first identified using data from the Transiting Exoplanet Survey Satellite (TESS). TOI-2336b has a radius of \(1.05\pm 0.04\ R_J\), a mass of \(69.9\pm 2.3\ M_J\) and an orbital period of 7.71 days. TOI-1608b has a radius of \(1.21\pm 0.06\ R_J\), a mass of \(90.7\pm 3.7\ M_J\) and an orbital period of 2.47 days. TOI-2521b has a radius of \(1.01\pm 0.04\ R_J\), a mass of \(77.5\pm 3.3\ M_J\) and an orbital period of 5.56 days. We found all these low-mass companions are inflated. We fitted a relation between radius, mass and incident flux using the sample of known transiting brown dwarfs and low-mass M dwarfs. We found a positive correlation between the flux and the radius for brown dwarfs and for low-mass stars that is weaker than the correlation observed for giant planets. We also found that TOI-1608 and TOI-2521 are very likely to be spin-orbit synchronized, leading to the unusually rapid rotation of the primary stars considering their evolutionary stages. Our estimates indicate that both systems have much shorter spin-orbit synchronization timescales compared to their ages. These systems provide valuable insights into the evolution of stellar systems with brown dwarf and low-mass stellar companions influenced by tidal effects.
The radius valley carries implications for how the atmospheres of small planets form and evolve, but this feature is visible only with highly precise characterizations of many small planets. We ...present the characterization of nine planets and one planet candidate with both NASA TESS and ESA CHEOPS observations, which adds to the overall population of planets bordering the radius valley. While four of our planets - TOI 118 b, TOI 455 b, TOI 560 b, and TOI 562 b - have already been published, we vet and validate transit signals as planetary using follow-up observations for five new TESS planets, including TOI 198 b, TOI 244 b, TOI 262 b, TOI 444 b, and TOI 470 b. While a three times increase in primary mirror size should mean that one CHEOPS transit yields an equivalent model uncertainty in transit depth as about nine TESS transits in the case that the star is equally as bright in both bands, we find that our CHEOPS transits typically yield uncertainties equivalent to between two and 12 TESS transits, averaging 5.9 equivalent transits. Therefore, we find that while our fits to CHEOPS transits provide overall lower uncertainties on transit depth and better precision relative to fits to TESS transits, our uncertainties for these fits do not always match expected predictions given photon-limited noise. We find no correlations between number of equivalent transits and any physical parameters, indicating that this behavior is not strictly systematic, but rather might be due to other factors such as in-transit gaps during CHEOPS visits or nonhomogeneous detrending of CHEOPS light curves.
Hot Jupiters were many of the first exoplanets discovered in the 1990s, but in the decades since their discovery, the mysteries surrounding their origins remain. 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 (MEEP) 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 (0.55 Jupiter masses (M\(_{\rm{J}}\)) \(<\) M\(_{\rm{P}}\) \(<\) 3.88 M\(_{\rm{J}}\)) and sizes (0.967 Jupiter radii (R\(_{\rm{J}}\)) \(<\) R\(_{\rm{P}}\) \(<\) 1.438 R\(_{\rm{J}}\)) and orbit stars that range in temperature from 5360 K \(<\) Teff \(<\) 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 (\(e = 0.259^{+0.033}_{-0.036}\)) and TOI-5301 b (\(e = 0.33^{+0.11}_{-0.10}\)). 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.
Warm Jupiters are close-in giant planets with relatively large planet-star separations (i.e., \(10< a/R_\star <100\)). Given their weak tidal interactions with their host stars, measurements of ...stellar obliquity may be used to probe the initial obliquity distribution and dynamical history for close-in gas giants. Using spectroscopic observations, we confirm the planetary nature of TOI-1859b and determine the stellar obliquity of TOI-1859 to be \(\lambda = 38.9^{+2.8}_{-2.7}\deg\) relative to its planetary companion using the Rossiter-McLaughlin effect. TOI-1859b is a 64-day warm Jupiter orbiting around a late-F dwarf and has an orbital eccentricity of \(0.57^{+0.12}_{-0.16}\), inferred purely from transit light curves. The eccentric and misaligned orbit of TOI-1859b is likely an outcome of dynamical interactions, such as planet-planet scattering and planet-disk resonance crossing.
