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1. The Polar Orbit of TOI-2374 b, a Planet in the Neptunian Ridge

   https://doi.org/10.3847/1538-3881/ae070b  

   Yee, Samuel W; Tamburo, Patrick; Stefánsson, Gudmundur; García-Mejía, Juliana; Charbonneau, David; Barkaoui, Khalid; Collins, Karen A; Schwarz, Richard P; Narita, Norio; Fukui, Akihiko; et al (October 2025, The Astronomical Journal)

   Abstract The “Neptunian ridge” is a recently identified peak in the frequency of planets with sizes between that of Neptune and Saturn orbiting their host stars with periods between 3 and 6 days. These planets may have formed similarly to their larger, hot Jupiter counterparts in the “3 day pileup,” through a dynamically excited migration pathway. The distribution of stellar obliquities in hot Neptune systems may therefore provide a vital clue as to their origin. We report a new stellar obliquity measurement for TOI-2374b, a planet in the Neptunian ridge (P= 4.31 days,R_p = 7.5R_⊕). We observed a spectroscopic transit of TOI-2374b with the Keck Planet Finder, detecting the Rossiter–McLaughlin (RM) anomaly with an amplitude of 3 m s⁻¹, and measured a sky-projected obliquity of $\lambda ={81°}_{-22^{\circ }}^{+23^{\circ }}$ , indicating an orbit significantly misaligned with the spin axis of its host star. A reloaded RM analysis of the cross-correlation functions confirms this misalignment, measuring $\lambda ={65°}_{-24^{\circ }}^{+32^{\circ }}$ . Additionally, we measured a stellar rotation period of $P_{\mathrm{rot}}=26.4_{-0.8}^{+0.9}$ days with photometry from theTierrasobservatory, allowing us to deduce the three-dimensional stellar obliquity of $\psi ={85\stackrel{°}{.}9}_{-9\stackrel{°}{.}2}^{+8\stackrel{°}{.}6}$ . TOI-2374b joins a growing number of hot Neptunes on polar orbits. The high frequency of misaligned orbits for Neptunian ridge and desert planets, compared with their longer period counterparts, is reminiscent of patterns seen for the giant planets and may suggest a similar formation mechanism. 

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2. The OATMEAL Survey. II. The 3D Spin–Orbit Obliquity of an Eccentric Transiting Brown Dwarf in the Ruprecht 147 Open Cluster

   https://doi.org/10.3847/1538-3881/ae19e8  

   Carmichael, Theron W; Giacalone, Steven; Vowell, Noah; Huber, Daniel; Wang, Xian-Yu; Bossett, Malik; Handley, Luke; Householder, Aaron; Li, Yaguang; Fulton, Benjamin J; et al (December 2025, The Astronomical Journal)

   Abstract We present a new analysis of the CWW 89 system as part of the Orbital Architectures of Transiting Massive Exoplanets And Low-mass stars (OATMEAL) survey. The CWW 89 system is a member of the 2.8 Gyr old Ruprecht 147 (NGC 6774) cluster and consists of two stars, CWW 89A (EPIC 219388192) and CWW 89B, with the primary hosting a transiting brown dwarf, CWW 89Ab. We use in-transit, highly precise radial velocity measurements with the Keck Planet Finder to characterize the Rossiter–McLaughlin (RM) effect and measure the projected spin–orbit obliquity ∣λ∣ = 1 $\stackrel{\text{°}}{.}$ 4 ± 2 $\stackrel{\text{°}}{.}$ 5 and the full 3D spin–orbit obliquity of the brown dwarf to be $\psi =15.1_{-10.9}^{+15.0^{\circ }}$ . This value ofλimplies that the brown dwarf’s orbit is prograde and well-aligned with the equator of the host star, continuing the trend of transiting brown dwarfs showing a preference for spin–orbit alignment (λ ≈ 0°) regardless of the stellar effective temperature. This contrast with the transiting giant planet population, whose spin–orbit alignments depend on hostT_eff, shows an increasingly clear distinction in the formation and orbital migration mechanisms between transiting giant planets and transiting brown dwarfs like CWW 89Ab. For this system in particular, we find it plausible that the brown dwarf may have undergone coplanar high-eccentricity migration influenced by CWW 89B. 

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3. The True Stellar Obliquity of a Sub-Saturn Planet from the Tierras Observatory and the Keck Planet Finder

   https://doi.org/10.3847/1538-3881/add530  

   Tamburo, Patrick; Yee, Samuel W; García-Mejía, Juliana; Stefánsson, Gudmundur; Charbonneau, David; Bieryla, Allyson; Howard, Andrew W; Isaacson, Howard; Fulton, Benjamin J; Householder, Aaron (June 2025, The Astronomical Journal)

   Abstract We measure the true obliquity of TOI-2364, a K dwarf with a sub-Saturn-mass (M_p = 0.18M_J) transiting planet on the upper edge of the hot-Neptune desert. We used new Rossiter–McLaughlin observations gathered with the Keck Planet Finder to measure the sky-projected obliquityλ = 7° + 10°–11°. Combined with a stellar rotation period of 23.47 ± 0.29 days measured with photometry from theTierrasObservatory, this yields a stellar inclination of 90° ± 13° and a true obliquityψ = 15 $\stackrel{\text{°}}{.}$ 6 + 7 $\stackrel{\text{°}}{.}$ 7–7 $\stackrel{\text{°}}{.}$ 3, indicating that the planet’s orbit is well aligned with the rotation axis of its host star. The determination ofψis important for investigating a potential bimodality in the orbits of short-period sub-Saturns around cool stars, which tend to be either aligned with or perpendicular to their host stars’ spin axes. 

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4. TOI-4495: A Pair of Aligned, Near-resonant Sub-Neptunes That Likely Experienced Overstable Migration

   https://doi.org/10.3847/1538-3881/ae346d  

   Wang_王, Mu-Tian 牧天; Dai_戴, Fei 飞; Liu_刘, Hui-Gen 慧根; Masuda, Kento; Howard, Andrew W; Halverson, Samuel; Isaacson, Howard; Zhang, Elina Y; Goldberg, Max; Teng, Huan-Yu; et al (February 2026, The Astronomical Journal)

   Abstract We report the discovery of a sub-Neptune and a Neptune-like planet (R ${}_b=2.48_{-0.10}^{+0.14}$ R_⊕,R ${}_c=4.03_{-0.15}^{+0.23}$ R_⊕) orbiting the F-type star TOI-4495. The planets have orbital periods of 2.567 and 5.185 days, lying close to a 2:1 mean-motion resonance (MMR). Our photodynamical analysis of the TESS light curves constrains the planetary masses toM_b = 7.7 ± 1.4M_⊕and M_c = 23.2 ± 4.7M_⊕. The measured masses and radii indicate the presence of volatile-rich gaseous envelopes on both planets. The Rossiter–McLaughlin effect and the Doppler shadow of TOI-4495 c reveal a well-aligned orbit with a projected stellar obliquity of $\lambda =-2.3_{-7.8}^{+8.3}°$ . Combined with the low mutual inclination constrained by the photodynamical analysis (ΔI < 8.7°), the planetary orbits are likely coplanar and aligned with the host star’s spin axis. We show that the planets are near, but not in, the 2:1 MMR, with a circulating resonant angle. We also find substantial free eccentricity for the inner planet, TOI-4495 b ( $e_b=0.078_{-0.013}^{+0.02}$ ). Given the observed proximity to the 2:1 resonance and the more massive outer planet, TOI-4495 b and c are particularly susceptible to resonant overstability, which in turn can explain the observed eccentricity by converting resonantly excited eccentricity into free eccentricity. However, additional mechanisms (e.g., planetesimal scattering) may be required to further excite the eccentricity by ∼4%. To prevent tidal damping from reducing the eccentricity below the observed level over the star’s lifetime (1.9 Gyr), the reduced tidal quality factor of TOI-4495 b must be $Q^{\prime }\gtrsim 10^5$ , consistent with the presence of a thick envelope on the planet. 

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5. Observation of a pseudoscalar excess at the top quark pair production threshold

   https://doi.org/10.1088/1361-6633/adf7d3  

   Collaboration, The CMS (August 2025, Reports on Progress in Physics)

   Abstract A search for resonances in top quark pair ( $\mathrm{t}\bar{\mathrm{t}}$ ) production in final states with two charged leptons and multiple jets is presented, based on proton–proton collision data collected by the CMS experiment at the CERN LHC at $\sqrt{s}=13\text{TeV}$ , corresponding to 138 fb⁻¹. The analysis explores the invariant mass of the $\mathrm{t}\bar{\mathrm{t}}$ system and two angular observables that provide direct access to the correlation of top quark and antiquark spins. A significant excess of events is observed near the kinematic $\mathrm{t}\bar{\mathrm{t}}$ threshold compared to the non-resonant production predicted by fixed-order perturbative quantum chromodynamics (pQCD). The observed enhancement is consistent with the production of a color-singlet pseudoscalar ( ${}^1{\text{S}}_0^{\left[1\right]}$ ) quasi-bound toponium state, as predicted by non-relativistic quantum chromodynamics. Using a simplified model for ${}^1{\text{S}}_0^{\left[1\right]}$ toponium, the cross section of the excess above the pQCD prediction is measured to be $8.8{}_{-1.4}^{+1.2}\text{pb}$ . 

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