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Through the Rossiter–McLaughlin effect, several hot Jupiters have been found to exhibit spin–orbit misalignment and even retrograde orbits. The high obliquity observed in these planets can be attributed to two primary formation mechanisms, as summarized in the existing literature. First, the host star's spin becomes misaligned with the planetary disk during the late stages of star formation, primarily due to chaotic accretion and magnetic interactions between the star and the planetary disk. Second, the orbital inclination of an individual planet can be excited by dynamical processes such as planet–planet scattering, the Lidov–Kozai cycle, and secular chaos within the framework of Newtonian mechanics. This study introduces a third mechanism, where, within the framework of general relativity, the post-Newtonian spin–orbit coupling term induces precession of the host star's spin around the orbital angular momentum. The orbital inclination, relative to a reference plane, can expand the range of deviation in the spatial orientation of the bodies’ spins from the plane's normal. The varying amplitude and period of spin precession for both the star and the planet are derived theoretically, and the results, which can be applied without restriction, agree well with numerical simulations.

TOI-1338 is the first circumbinary planet (CBP) system discovered by TESS. It has one transiting planet at P ∼ 95 days and an outer nontransiting planet at P ∼ 215 days complemented by radial velocity (RV) observation. Here we present a global photodynamical modeling of the TOI-1338 system that self-consistently accounts for the mutual gravitational interactions between all known bodies in the system. As a result, the three-dimensional architecture of the system can be established by comparing the model with additional data from TESS Extended Mission and published HARPS/ESPRESSO RV data. We report an inconsistency of binary RV signal between HARPS and ESPRESSO, which could be due to the contamination of the secondary star. According to stability analysis, the RV data via ESPRESSO are preferred. Our results are summarized as follows: (1) The inner transiting planet is extremely coplanar to the binary plane Δ I _b ∼ 0.°12, making it a permanently transiting circumbinary planet at any nodal precession phases; we updated the future transit ephemerides with improved precisions. (2) The outer planet, despite its untransiting nature, is also coplanar with the binary plane by ${\rm{\Delta }}{I}_{c}=9\buildrel{\circ}\over{.} {1}_{-4\buildrel{\circ}\over{.} \,8}^{+6\buildrel{\circ}\over{.} \,0}$ (22° for the 99% upper limit). (3) The inner planet could have an extremely low density of 0.137 ± 0.026 g cm ^−3 . With a TESS magnitude of 11.45, TOI-1338 b is an optimal circumbinary planet CBP for ground-based follow-up and transit spectroscopy.

Planets in young star clusters could shed light on planet formation and evolution since star clusters can provide accurate age estimation. However, the number of transiting planets detected in clusters was only ∼30, too small for statistical analysis. Thanks to the unprecedented high-precision astrometric data provided by Gaia DR2 and Gaia DR3, many new open clusters (OCs) and comoving groups have been identified. The Understanding Planetary Formation and Evolution in Star Clusters project aims to find observational evidence and interpret how planets form and evolve in cluster environments. In this work, we cross match the stellar catalogs of new OCs and comoving groups with confirmed planets and candidates. We carefully remove false positives and obtain the biggest catalog of planets in star clusters up to now, which consists of 73 confirmed planets and 84 planet candidates. After age validation, we obtain the radius–age diagram of these planets/candidates. We find an increment in the fraction of hot Jupiters (HJs) around 100 Myr and attribute the increment to the flyby-induced high- e migration in star clusters. An additional small bump of the fraction of HJs after 1 Gyr is detected, which indicates the formation timescale of HJ around field stars is much larger than that in star clusters. Thus, stellar environments play important roles in the formation of HJs. The hot Neptune desert occurs around 100 Myr in our sample. A combination of photoevaporation and high- e migration may sculpt the hot Neptune desert in clusters.

EX Lup is the archetype for the class of young stars that undergoes repeated accretion outbursts of ∼5 mag at optical wavelengths that last for months. Despite extensive monitoring that dates back 130 yr, the accretion history of EX Lup remains mostly qualitative and has large uncertainties. We assess historical accretion rates of EX Lup by applying correlations between optical brightness and accretion, developed on multi-band magnitude photometry of the ∼2 mag optical burst in 2022. Two distinct classes of bursts occur: major outbursts (Δ V ∼ 5 mag) have year-long durations, are rare, reach accretion rates of ${\dot{M}}_{\mathrm{acc}}\sim {10}^{-7}$ M _⊙ yr ^−1 at peak, and have a total accreted mass of around 0.1 Earth mass. The characteristic bursts (Δ V ∼ 2 mag) have durations of ∼2–3 months, are more common, reach accretion rates of ${\dot{M}}_{\mathrm{acc}}\sim {10}^{-8}$ M _⊙ yr ^−1 at peak, and have a total accreted mass of around 10 ^−3 Earth masses. The distribution of total accreted mass in the full set of bursts is poorly described by a power law, which suggests different driving causes behind the major outburst and characteristic bursts. The total mass accreted during two classes of bursts is around 2 times the masses accreted during quiescence. Our analysis of the light curves reveals a color-dependent time lag in the 2022 post-burst light curve, attributed to the presence of both hot and cool spots on the stellar surface.