Mastodawn

So, uh, 6 recent #exoplanet arχiv papers that I thought were neat and would encourage people to check out:
Characterizing the atmospheres of 5 hot Jupiters with JWST (1 is completely featureless, so probably cloudy): https://arxiv.org/abs/2603.21273

High-resolution spectroscopic atmospheric studies of 5 hot Jupiters across the edge of the Neptune desert

Hot Jupiters (HJs), especially the Ultra-Hot Jupiters (UHJs), are ideal targets for robust atmospheric characterization, thanks to their high equilibrium temperatures and large atmospheric scale heights, which result from their proximity to their host stars and intense stellar irradiation. Here, we present atmospheric studies of five planets, namely WASP-50b, WASP-117b, WASP-156b, WASP-167b, and WASP-173Ab. These five planets include two UHJs, two classic HJs, and one hot Neptune, with four of them just on the upper and middle borders of the Neptune desert, providing an interesting sample for investigating the connection between planetary atmospheric composition and bulk properties. We have not detected any significant absorption signals exceeding 3$σ$ in the three less-inflated, relatively high-density HJs (WASP-50b, WASP-156b, and WASP-173Ab). We marginally detect H$α$ and Li I with 3.2$σ$ and 3.1$σ$ in WASP-117b, respectively. In WASP-167b, we report tentative detection of H$α$ and Fe I at 4.6$σ$ and $\sim3.4σ$, receptively. In addition, Fe I is significantly detected with a max SNR of 7.3 $σ$ using the cross-correlation technique, which exhibits a blue-shifted signal. For WASP-167b, we perform an atmospheric retrieval and yield the abundances of Fe, Mg, Ca, Ti, V, and equilibrium temperature of ${2479^{+193}_{-174}}$K. Comparing WASP-173Ab and WASP-167b, both are UHJ, but with quite different extents of atmospheric signals, we propose that there may be a transition in $T_{\rm eq}$ between 1900 and 2300K.

arXiv.org

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raptop (𒀯 𒄷 𒄈𒀭𒁇)3d ago

A large sample of Kepler planets suggests that while ones around binary systems exhibit “peas-in-a-pod” architectures in terms of planet sizes, like around single ones, the systems tend to have more single planets (as opposed to 2+), and what multiple planet systems are found are more compact (and with 3+ a more complex gap spacing): https://arxiv.org/abs/2603.21897

Planetary Architectures of Kepler Compact Multis with Binary Star Companions

Planets in binary-star systems exhibit demographic differences compared to planets in single-star systems. In particular, planets with binary-star hosts have a lower overall occurrence rate compared to their single-star counterparts, as well as a suppressed relative occurrence rate for sub-Neptunes ($R_p=2{-}4R_{\oplus}$) compared to super-Earths ($R_p=1.0{-}1.5R_{\oplus}$). These differences are most pronounced in close separation binaries ($ρ< 100$ au) which has been interpreted as a result of binary stars disrupting the protoplanetary disks of their stellar companions. The architectures of planetary systems -- i.e. the arrangements of planet sizes and orbits -- provide additional information about system formation and evolution. Architectures of single-star planetary systems are well studied, but architectures of binary-star planetary systems have not been investigated in detail. In this work, we analyzed a large sample of Kepler planetary systems (162 planets in 118 binary-star systems; 880 planets in 544 single-star systems) to compare their architectures as a function of stellar multiplicity. We found that planets with binary-star hosts follow a similar ``peas-in-a-pod'' tendency toward uniformity in planet radii and log-uniformity in period spacing as planets with single-star hosts. However, we also detected modest ($2.5-3σ$) differences in period spacing and planet multiplicity, with binary-star systems having higher typical gap complexities (indicating more uneven spacing) and a higher prevalence of single planets. We interpret these results as evidence that binary stars primarily influence the planetary architectures of their stellar companions by shaping the protoplanetary disk at formation, with subsequent dynamical processing more gently altering the system architectures over secular timescales.

arXiv.org

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raptop (𒀯 𒄷 𒄈𒀭𒁇)

And a day later, another way of slicing the Kepler Data shows that generally systems with more planets have lower eccentricities, and gives a scale of how many non-transiting planets we're missing in ones where we're finding one or more planets. But also that a lot of 'fancier' architectures that have been proposed are uncommon.

https://arxiv.org/abs/2603.23644

No strong associations between eccentricity and orbital architecture in Kepler compact multis

The dynamical history of a planetary system is recorded in the present day architecture of its constituent planets' sizes, orbital periods, and eccentricities. Studying the relationships between these quantities for large populations provides a window into the processes by which planetary systems form and evolve. Recently, Gilbert, Petigura, and Entrican (2025) performed a hierarchical Bayesian analysis of 1626 planets from the Kepler census, demonstrating a strong relationship between planet radius $R_p$ and orbital eccentricity $e$. Here, we build upon that work to search for correlations between eccentricity and system architecture, focusing on compact systems of small planets. We find that small planets on short orbits ($P < 4$ days) show evidence of tidal circularization. This trend is well established for Jovian planets but a novel finding for super-Earths and sub-Neptunes. We reproduce the known wherein trend single-transiting systems possess elevated eccentricities relative to their multi-transiting counterparts. We further show that systems with two transiting planets have higher eccentricities than those with three or more transiting planets. When compared to population synthesis models, these multiplicity-eccentricity relationships imply that Kepler singles have intrinsic multiplicity ${\sim}3$ and Kepler multis have intrinsic multiplicity ${\sim}4{-}6$. We detect no statistically significant associations between eccentricity and planetary period ratios, gap complexity, size inequality, or size ordering. We interpret these findings as evidence either in favor of a quiescent formation history or against dynamical processes which excite eccentricity but not inclination. Sub-significant relationships between eccentricity and architecture imply that subtle, multi-factor trends may be detectable in the future using more sophisticated statistical techniques.

arXiv.org