Earth and Planetary Astrophysics
Astro-Hunters: Machine Learning for Exoplanet Transit Detection in TESS Photometry
Fatimah Emad Eldin
Finding
planets beyond the Solar System is now largely a data-analysis problem: photometric surveys return far more stellar light curves than can be inspected by eye, and machine learning is increasingly asked to recognise the faint, periodic dimming of a transiting
planet. Whether such a detector works turns on a choice that is seldom reported: how its training labels were made. No catalogue disposes the individual measurements a per-cadence detector must classify, so the annotation has to be derived, and this paper asks what that costs. We present Astro-Hunters, an end-to-end pipeline over TESS two-minute photometry:
retrieval, detrending, seven sliding-window statistics per cadence, and gradient-boosted classification. These components are deliberately conventional. What is new is the treatment of label provenance as an experimental variable, a corpus of 189,279 cadences from twelve confirmed hosts annotated from published ephemerides rather than from the photometry, and a physical bound on what the task permits. Six classifier families are compared under a
star-disjoint protocol. Holding features, model and protocol fixed, precision–recall performance spans a factor of 29 across label sources against 1.8 across architectures. Labels from an isolation forest fitted to the classifier's own features give an apparent AUC of 0.9915 that measures circularity; an unconverted transit epoch drives performance to chance; correct annotation gives AUC 0.788 at 5.3 times the prevalence baseline. The ceiling is observational, not architectural: a median single-cadence signal-to-noise ratio of 2.10 caps per-cadence AUC at 0.932. A Box Least Squares baseline recovers eight of twelve orbital periods from one sector. Phase-folding, not classifier capacity, is what makes the transit signal accessible.
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Earth and Planetary Astrophysics
Atmospheric Reconnaissance of TRAPPIST-1 f with JWST NIRISS SOSS: No Evidence for the Transit Light Source Effect
Olivia Lim, René Doyon, Ryan J. MacDonald et al. (+25 more)
In just over three years of operation, JWST has observed all seven
planets of the TRAPPIST-1 system. The two innermost
planets were found to have little to no atmosphere, barring the presence of high-altitude aerosols. Here we present the first JWST transit spectra of the habitable-zone
exoplanet TRAPPIST-1 f, which were obtained with NIRISS SOSS over the course of five transits. At least one stellar
flare occurred in each visit, but unlike observations of closer-in TRAPPIST-1
planets, no evidence for contamination of the transit spectra from unocculted stellar surface heterogeneities was found. This non-detection does not guarantee the absence of unocculted heterogeneities in all future transit observations of this
planet, and it could be explained by the transit chord of TRAPPIST-1 f having properties similar to the average, out-of-transit, visible stellar hemisphere at the time of observation. The transit spectra exhibit slopes ranging from -365 ppm/um down to 15 ppm/um, which we attribute to stellar variability, that is,
flares and/or smaller-scale events. The visits least affected by
flares rule out H2/He-dominated atmospheres with surface pressures higher than about 20 mbar at 95% confidence. For high-mean-molecular-mass atmospheres, the exact upper limits on surface pressures depend on the reduction pipeline and on the treatment of the residual slopes in the transit spectra.
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All authors Olivia Lim, René Doyon, Ryan J. MacDonald, Étienne Artigau, Michael Radica, Mykhaylo Plotnykov, Alexandrine L'Heureux, Caroline Piaulet-Ghorayeb, Louis-Philippe Coulombe, David Lafrenière, Thomas J. Fauchez, Martin Turbet, Diana Valencia, Loïc Albert, Laura Flagg, Björn Benneke, Neil J. Cook, Pierre-Alexis Roy, Lisa Kaltenegger, Charles Cadieux, Nicolas B. Cowan, Michaël Gillon, Romain Allart, Lisa Dang, Doug Johnstone, Stefan Pelletier, Jared Splinter, Jake Taylor
Earth and Planetary Astrophysics · Cross-listed from astro-ph.IM
The Roman Coronagraph Community Participation Program: Observation planning and data reduction for polarimetric mode
Ramya M Anche, Toshiyuki Mizuki, Justin Hom et al. (+25 more)
Reflected-light polarimetry of
exoplanets constrains and resolves degeneracies in atmospheric properties, while polarized light observations of debris disks enable the characterization of dust-grain properties. The best-effort polarimetric mode of the Roman Coronagraph Instrument will be able to perform multi-wavelength observations of planetary systems using both the Hybrid Lyot Coronagraph (HLC) and the Shaped Pupil Coronagraph (SPC). This paper presents an overview of observation planning, simulations, and data reduction procedures for the polarimetric mode of the Roman Coronagraph. As an initial test of simulation and data reduction, a
dataset of polarimetric observing sequences for the debris disk HD 172555 in HLC mode was generated using corgisim with estimated observation parameters, and data reduction was performed using corgidrp, incorporating all relevant noise factors and calibration products. Currently, mock calibration products are used in corgidrp; these will be replaced with simulated calibration products in future updates
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All authors Ramya M Anche, Toshiyuki Mizuki, Justin Hom, Alexis Lau, Saanika Choudhary, Jaren N. Ashcraft, Clarissa Do O, Tsutsumi Nagai, Sophie Noiret, Eric Shen, Taichi Uyama, Chen Xie, Jingwen Zhang, Vanessa P. Bailey, Eric Cady, Jessica Gersh-Range, Julien H. Girard, Guillermo Gonzalez, John Livingston, Bertrand Mennesson, Maxwell A. Millar-Blanchaer, Julia Milton, Naoshi Murakami, Dmitry Savransky, Motohide Tamura, Jason J. Wang, Schuyler G. Wolff, Marie Ygouf
Earth and Planetary Astrophysics · Cross-listed from astro-ph.IM
The Roman Coronagraph Community Participation Program: pre-launch reference star list and impact of reference star properties on post-processing performance
Justin Hom, Schuyler G. Wolff, Jessica Gersh-Range et al. (+51 more)
The upcoming Roman Coronagraph will be the first high-contrast instrument in space capable of high-order wavefront sensing and control technologies, a critical technology demonstration for the proposed Habitable Worlds Observatory (HWO) that aims to directly image and characterize habitable exoEarths. The nominal Roman Coronagraph observing plan involves alternating observations of a science target and a bright, nearby reference
star for both wavefront calibration and reference differential imaging post-processing. Reference
star criteria for the most demanding coronagraph mode are restrictive, limiting the sample to only 40 candidates for which thorough observational vetting is needed to assess their suitability. Reference
star properties such as resolved diameters, presence of circumstellar dust, and close point sources may also have more subtle impacts on post-processing efficacy that may inhibit final contrast performance. In this work, we describe the current progress of the CoronaGraph Instrument Reference
stars for
Exoplanets (CorGI-REx) observing campaign, a 300+-hour observing campaign that utilizes instruments from around the world to vet reference
stars for high-order wavefront control suitability. We will present the pre-launch list of reference
star candidates being utilized for the Roman Coronagraph Observation Phase constructed from a thorough analysis of high contrast and interferometric observations. We will also present the results of simulations investigating the impact of reference
star resolved diameters and companions on post-processing performance. We conclude by discussing the importance of reference
star selection for scheduling observations and optimizing contrast performance for the Roman Coronagraph along with implications for HWO coronagraph operations.
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All authors Justin Hom, Schuyler G. Wolff, Jessica Gersh-Range, Ramya M. Anche, Vanessa P. Bailey, Jean-Philippe Berger, Beth A. Biller, Wolfgang Brandner, Marah Brinjikji, Gaël Chauvin, David R. Ciardi, Catherine A. Clark, Laird M. Close, Robert J. De Rosa, Sarah Deveny, Warren B. Foster, Julien H. Girard, Alexandra Z. Greenbaum, Olivier Guyon, Sebastiaan Y. Haffert, Alexander D. Hedglen, Steve B. Howell, Parker T. Johnson, Maggie Y. Kautz, Jay K. Kueny, Masayuki Kuzuhara, Manon Lallement, Rico Landman, Colin Littlefield, Jean-Baptiste Le Bouquin, Jialin Li, Joshua Liberman, Joseph D. Long, Miles Lucas, Jennifer Lumbres, Bruce Macintosh, Jared R. Males, Eric Mamajek, Matthijs Mars, Eden A. McEwen, Avalon L. McLeod, Maxwell A. Millar-Blanchaer, Toshiyuki Mizuki, Sophie Noiret, Tiffany Nguyen, Lauren Schatz, Nicholas T. Schragal, Adam K. Taras, Elena Tonucci, Katie Twitchell, Kyle Van Gorkom, Macarena C. Vega-Pallauta, Jason J. Wang, Jingwen Zhang
Earth and Planetary Astrophysics
Understanding the Energy Input Required for Methane Emission on CWISEP J193518.59-154620.3: A Comprehensive Analysis
Kayla J. Smith, Mark S. Marley, Tommi T. Koskinen et al. (+1 more)
The Y dwarf WISE 1935 exhibits a thermal inversion in its radiative atmosphere, producing methane emission features in its JWST spectrum, but the physical mechanism responsible for this inversion remains unknown. Using the open-source radiative–convective
equilibrium code PICASO, we model atmospheric heating with Chapman energy deposition profiles to reproduce the observed thermal inversion and methane emission feature. Our models require heating rates of approximately 10^5-10^6 erg cm^-2 s^-1. We show that the atmospheric response depends primarily on the integrated heating deposited in the observable atmosphere, revealing a degeneracy between heating magnitude, vertical extent, and emitting surface fraction. Disequilibrium chemistry lowers the required energy input by lowering CH$_4$ opacity and strengthening the inversion. Comparison with recent electron-beam heating models indicates that reproducing the thermal inversion in W1935 requires substantially greater energy deposition than currently predicted for brown dwarf auroral heating, while the observed methane emission favors energy deposition near 10^-3-10^-2 bar. Our models also predict a prominent methane emission feature near 7.8 microns, along with energy-sensitive ammonia features near 6 microns, implying a bolometric luminosity greater than that yet measured. Finally, we investigate potential sources of the inferred upper-atmospheric heating. We find that Joule heating would require a strong
magnetic field and large electron densities, the latter supported by external ionization from an unidentified source. We also consider cometary impacts as a possible source of atmospheric heating.
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All authors Kayla J. Smith, Mark S. Marley, Tommi T. Koskinen, James Mang
Earth and Planetary Astrophysics
SCExAO/CHARIS High-Contrast Pre-Launch Vetting of Roman Coronagraph Technology Demonstration PSF Reference Stars
Thayne Currie, Jie Li, Mona El Morsy et al. (+9 more)
We present deep, SCExAO/CHARIS high-contrast integral field spectroscopy and archival imaging of four candidate Roman Coronagraph PSF reference
stars within/near the Roman Continuous Viewing Zone and potentially suitable for the Coronagraph's key technology demonstration targets HIP 71618 and HIP 54515. For CHARIS data, we achieve 5-$\sigma$ contrasts down to $\sim$1.4$\times$10$^{-5}$, $\sim$6$\times$10$^{-6}$, and 10$^{-6}$ to 4$\times$10$^{-7}$ at 0\farcs{}16, 0\farcs{}25, and 0\farcs{}5 to 1\arcsec{}. Companion mass limits rule out brown dwarfs at $\rho$ $\sim$ 0\farcs{}15–0\farcs{}25 and massive
planets at wider separations around all targets. More critically, for three of the four references our analysis disfavors companions with $V$ band contrasts brighter than 10$^{-8}$, 10$^{-9}$, and $10^{-10}$ at 0\farcs{}15, 0\farcs{}3, and 1$\arcsec{}$. Unless these targets have faint substellar companions within $\rho$ $\sim$ 0\farcs{}15, they likely lack background
stars or companions that could corrupt the Roman Coronagraph's dark hole digging to preclude detecting reflected-light
planets. For $\alpha$ Cep, our limits are a factor of $\sim$10 worse but still meet the TTR5 limit of 10$^{-7}$ beyond $\rho$ $\sim$ 0\farcs{}25: beyond 0\farcs{}4, they exclude a Jupiter-twin reflected-light companion (10$^{-9}$). Archival Keck/NIRC2 data likewise find no substellar companions with $\Delta$V $>$ 10$^{-8}$ at wider separations. Finally, we assess the observability of HIP 71618 and HIP 54515 – updated for Roman's launch date of August 30, 2026. Adding $\gamma$ Boo – not currently in the Roman CPP team reference-
star list – would improve schedulability for the tech demo's key targets.
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All authors Thayne Currie, Jie Li, Mona El Morsy, Olivier Guyon, Julien Lozi, Erica Dykes, Danielle Bovie, Sebastien Vievard, Garima Singh, Kyohoon Ahn, Vincent Deo, Yoshito Ono
Earth and Planetary Astrophysics
A Statistical Mechanics Model for Stable Rings Outside the Roche Limit
Jack T. Dinsmore
Stellar occultations have revealed two rings around the dwarf
planet Quaoar outside the Roche limit. Simulations suggest that the rings are sustained by large velocity dispersions. We present the first analytical, first-principles theory that extends the Roche limit to describe planetary rings with large velocity dispersion. The underlying principle is an analogy between a
liquid/gas phase transition and the moon/ring transition: just as high temperatures can boil a
liquid under pressure, high velocity dispersions can stabilize ring systems beyond the Roche limit. We employ statistical mechanics to derive a modification to the Roche limit that treats rings with nonzero velocity dispersion. We demonstrate the new model's consistency with previous simulations of Quaoar's outermost ring. We also note that dense regions of the ring experience negative pressure, which would cause them to shrink over time if the assumptions of the model continue to hold. This could help explain the rings' azimuthal asymmetry.
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Earth and Planetary Astrophysics
GEMS JWST: Hold on to your HATS(-6 b), a sub-solar metallicity giant planet with water, methane and ammonia in its atmosphere
Giannina Guzmán Caloca, Caleb I. Cañas, Nicole L. Wallack et al. (+16 more)
HATS-6 b is one of several recently discovered Giant
Exoplanets orbiting M-dwarf
Stars (GEMS) and is part of a JWST survey that aims to compare bulk and atmospheric properties of these rare
planets against their FGK
star counterparts. HATS-6 b is a warm ($\mathrm{T_{eq}}\sim700$ K), Saturn-mass ($M_p\sim0.3~\mathrm{M_J}$), Jupiter-radius ($R_p\sim1~\mathrm{R_J}$)
planet that transits its
star every $\sim$ 3 days. In this study, we present the transmission spectrum of HATS-6 b obtained with two transits using the PRISM mode of JWST Near Infrared Spectrograph (NIRSpec), spanning a wavelength range of $0.6-5.3$ um. Analyzing these JWST observations using an iterative approach between forward modeling and free chemistry
retrievals, we derive a low
metallicity ($\log\mathrm{[M/H]}=-1.99^{+0.2}_{-0.2}$) sub-solar C/O ($\log\mathrm{[C/O]=-0.46^{+0.2}_{-0.2}}$) atmosphere, and find strong evidence for H$_2$O, CH$_4$, and NH$_3$ at volume mixing ratios (in $\log[X]$) of $-4.88_{-0.24}^{+0.25}$, $-5.38_{-0.19}^{+0.18}$, and $-6.03_{-0.19}^{+0.18}$, respectively. We consistently retrieve a significantly lower $\mathrm{T_{eq}}$ than predicted from the orbital configuration of HATS-6 b, which was impervious to any data reduction and
retrieval choices, suggesting a non-zero bond albedo. Our planetary interior models retrieve bulk
metallicities three orders of magnitude larger than our retrieved atmospheric
metallicity, also suggesting that the atmosphere is not well-mixed. We find an excess feature around 3 um, and expand on possible explanations for this, such as the presence of HCN or hydrocarbons like C$_2$H$_4$. Yet, due to the degeneracies present for hydrocarbon features in this wavelength region, we do not draw any conclusions about the excess feature and instead encourage further observations and follow-up of this intriguing target.
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All authors Giannina Guzmán Caloca, Caleb I. Cañas, Nicole L. Wallack, Erin M. May, Shang-Min Tsai, Simon Müller, Ravit Helled, Shubham Kanodia, Jacob Lustig-Yaeger, Knicole D. Colón, Ian Czekala, Megan Delamer, Peter Gao, Te Han, Jessica Libby-Roberts, Suvrath Mahadevan, Anjali A. A. Piette, Gu{\dh}mundur Stefánsson, Kevin B. Stevenson
Earth and Planetary Astrophysics
Causes of Hot Jupiter Inflation from Causal Discovery
Zehao Jin, Mohamad Ali-Dib, Yujia Zheng et al. (+3 more)
Hot Jupiters often have radii larger than predicted by standard cooling–contraction models, but it remains unclear which process supplies or preserves the extra internal heat. We analyze 328 short-period giant
planets with measured $M_p$, $R_p$, $P_{\rm orb}$, and host-
star $T_{\rm eff}$ using causal discovery, a statistical framework that asks which observed properties remain directly connected to
planet radius after the others are accounted for. As a check, the same pipeline recovers the expected mass–radius connection for a super-Earth control sample. For hot Jupiters, the preferred graph links $R_p$ directly to $P_{\rm orb}$ and $T_{\rm eff}$, but not to $M_p$. Since incident flux increases with $T_{\rm eff}$ and decreases with $P_{\rm orb}$ at fixed stellar properties, this paired dependence is naturally interpreted as a population-level signature of irradiation-regulated inflation. Comparing the graph with analytic radius-excess scalings suggests a comparatively important role for Gold–Soter thermal tides, with kinetic/mechanical heating and ohmic dissipation potentially contributing alongside them. Purely period-controlled gravitational tides are disfavored as the sole explanation because they lack a leading dependence on stellar temperature. Distinguishing thermal tides, kinetic/mechanical heating, ohmic dissipation, and mixed scenarios will require radius-excess measurements that control for incident flux, age, composition, stellar properties, and selection effects. More broadly, this work shows how causal discovery can turn population-level
exoplanet data into physically interpretable tests of hot-Jupiter inflation. Causal discovery complements parametric
Bayesian population models by testing which observables retain direct conditional dependence on $R_p$ without imposing a specific radius relation, although the modest sample size limits the scope of the inferred graph.
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All authors Zehao Jin, Mohamad Ali-Dib, Yujia Zheng, Mario Pasquato, Benjamin L. Davis, Andrea V. Maccio
Earth and Planetary Astrophysics · Cross-listed from astro-ph.IM
TomoSphero: Fast Differentiable Projector for Planetary and Solar Tomography on Spherical Grids
Evan Widloski and Lara Waldrop
Computational
tomography is a tool for determining the internal structure of objects from a set of projections, typically taken along some regular path. In recent years, methods and GPU-accelerated libraries have emerged that allow for fast reconstruction from projections along more complicated paths. Most of these libraries rely on a Cartesian discretization of the object, which is not appropriate for all scenarios. We present TomoSphero, a differentiable tomographic projector over spherical grids which are often used in planetary and solar
tomography. TomoSphero is designed to be used as a building block in reconstruction
algorithms and includes common projection types such as cone-beam and parallel-beam, but is flexible enough to accommodate arbitrary projections. TomoSphero is implemented in PyTorch which allows for fast projection computation on GPUs, easy access to modern machine learning optimizers, and automatic differentiation for rapid prototyping of parametric models.
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Earth and Planetary Astrophysics
Eclipse Timing of the Eccentric Planet HD 80606b with JWST: Constraints on a Second Planet and other Dynamical Effects
Charles Beichman, Billy Quarles, B.J. Fulton et al. (+6 more)
A variety of effects can perturb the orbital properties of single
planets in close orbits around their host
stars. HD80606 b is a highly eccentric ($\epsilon$=0.93)
exoplanet orbiting its host G5V
star, HD80606. HD80606 b became a compelling target for
exoplanet research after (Laughlin et al 2009) discovered that the 4.16 MJup
planet transits and is eclipsed by HD80606, thereby enabling photometric and spectroscopic observations to yield a wealth of information about the object. The exquisite precision of recent JWST eclipse timing offers an opportunity to investigate whether the orbit of HD80606 b is modified due to a variety of mechanisms, including General Relativity, tidal torques, or the presence of a second perturbing
planet. We have used over 25 years of radial velocity data plus eclipse and transit observations to place limits on the precession of HD80606 b's orbit and to assess which of these effects, if any, are observable. The new models are consistent with constant values of period, eccentricity and the argument of periastron, $\omega$, with a limit on $\dot{\omega}$ at the level of the predicted GR drift. The PRV and timing data limit the mass and location of a second
planet external to HD80606b. Timing offsets between JWST eclipses relative to the Pearson et al (2022) predictions are attributed to the poor constraints on $\sqrt{\epsilon} (\cos\ \omega, \sin\ \omega)$ with only the single eclipse measurement available (Spitzer 2009) in that analysis and to an over-weighting of the eclipse timing in that earlier analysis.
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All authors Charles Beichman, Billy Quarles, B.J. Fulton, Nikole Lewis, Ryan Challener, Julien de Wit, Malena Rice, Julie Inglis, Tiffany Kataria
Earth and Planetary Astrophysics
From Earth Meteors to Mars: Predicting Where to See the First Martian Meteors
Maximilian Vovk, Peter G. Brown and Denis Vida
Predictions of optical meteors at Mars have largely relied on classical single-body ablation models, despite high-resolution terrestrial observations showing that mm-sized meteoroids frequently fragment. This study quantifies how fragmentation alters the predicted brightness and peak-luminosity altitudes of sporadic mm-sized meteoroids in the Martian atmosphere and evaluates the single-body approximation as a reference baseline. Physical properties were inferred for 144 sporadic meteoroids observed on Earth using dynamic nested sampling with the erosion-fragmentation model. The resulting best-fit meteoroids were then re-simulated under Martian atmospheric conditions to generate predicted light curves. Because the physical trigger of fragmentation onset remains uncertain, three hypotheses were tested based on atmospheric mass density, dynamic pressure, and total accumulated heat. The results were also compared with predictions from a single-body ablation model. The data-driven simulations predict peak absolute magnitudes of $M_{\rm peak}\sim$ 2 - 7 for Martian meteors spanning diameters of 0.4 - 10 mm and entry speeds of 10 - 56 km/s. We find most events are luminous between $\sim$ 55 and 110 km heights. Relative to the single-body ablation baseline, the fragmentation-based predictions are brighter by $\sim$ 0.8 mag at peak brightness and concentrate luminosity within a narrower vertical range ($\sim$ 17 km instead of 36 km). The modelling accounting for fragmentation also produce shorter luminous trails ($\sim$ 20 km instead of 45 km). The resulting altitude-brightness maps provide observation-ready guidance for future Mars missions, while the fragmentation-based framework supports the interpretation of meteoroid-related ionospheric metal layers and improvements to Mars meteoroid-environment models.
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Earth and Planetary Astrophysics · Cross-listed from astro-ph.SR
Characterizing Stellar Flares in Ariel Targets: Activity Analysis and Transit Contamination
G. Galletta, S. Colombo and G. Micela
Stellar
flares are sudden releases of
magnetic energy that can distort
exoplanet transit photometry and transmission spectroscopy, biasing
planet radius estimates, transit timings, and atmospheric characterization. Understanding
flare activity in Ariel targets is therefore essential to identify
stars where
flares may compromise observations and to characterize the radiation environment affecting atmospheric escape and photochemistry. We analyzed 290 Ariel target
stars using TESS light curves.
Flares were identified via iterative Gaussian process detrending, and their energy distributions were modeled with two-segment power laws. We performed injection-recovery tests by adding synthetic
flares to detrended light curves and running the full pipeline to quantify completeness and detection biases. We detected 15,857
flares across 1,638 TESS sectors, with 2-86 events per sector. We defined a normalized
flare index GF.01 to compare activity across stellar luminosities. Near 3% of the sample exhibits enhanced
flare activity (GF.01 > 1). AU Mic and HD 28109 show a high likelihood of
flare contamination during transit observations. GF.01 correlates negatively with stellar bolometric luminosity, indicating higher relative
flare output in lower-luminosity
stars. AU Mic is an extreme case: four of five observed transits of AU Mic b are affected by
flares, consistent with statistical expectations. We validate the framework by comparing predicted
flare-contamination probabilities with observed
flare occurrences in a representative subset of transits, finding agreement within uncertainties. These results confirm that energetic
flares can significantly impact transit observations and provide quantitative guidance for Ariel target selection and analysis strategies.
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Earth and Planetary Astrophysics
Optical-NIR Multi-band Photometric Analysis and Characterization of Giant Exoplanets with CPI-C
Yiming Zhu, Gang Zhao, Xi Zhang et al. (+4 more)
We present a multi-band photometric approach to characterize giant
exoplanets, which represents one of the anticipated core scientific outcomes of Cool
Planet Imaging Coronagraph (CPI-C). CPI-C operates with two observational channels covering visible and near-infrared wavelengths, each equipped with four broadband filters. The
planet–
star flux ratio integrated over each filter bandpass is calculated for photometric analysis. For cool
planets observed in the visible bands, the data are primarily used to fit the overall spectral shape and methane-induced modulation, providing sensitivity to
metallicity- and cloud-dependent spectral variations while constraining the reflected-light spectral shape and the combined scaling involving
planet radius, orbital separation, and orbital phase. In the near-infrared bands, which probe thermal emission, the data help to better constrain fundamental planetary parameters including the effective temperature, radius, surface
gravity and mass. For a synthetic giant
planet with measurable reflected-light and thermal-emission components, the combined VIS4+NIR4 data provide tighter same-target constraints than either filter set alone, especially for the
planet radius and cloud sedimentation parameter. Our simulations incorporate realistic instrument throughput, detector noise, and residual speckle noise. The results demonstrate that the eight-band design spanning visible to near-infrared wavelengths supports reflected-light diagnostics, thermal-emission characterization, and joint optical–NIR analysis of giant
exoplanets within CPI-C science observations.
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All authors Yiming Zhu, Gang Zhao, Xi Zhang, Gang Wang, Bingli Niu, Zhonghua Lv, Jiangpei Dou
Earth and Planetary Astrophysics
The dust-rich, gas-depleted protosolar disk as the birthplace of chondrules
Sota Arakawa, Hidekazu Tanaka, Toshihiko Kadono et al. (+3 more)
Chondrules are the primary components of primitive meteorites known as chondrites, and understanding their formation and accumulation is essential for elucidating the history of
planet formation in the Solar System. Although a variety of chondrule formation mechanisms have been proposed, it remains challenging to satisfy the key constraints on chondrule abundance, formation timing, and mineralogical and chemical characteristics within a single model. In particular, the planetesimal bow-shock model, once considered one of the leading candidates, now faces a fundamental difficulty: Jupiter's formation likely depleted gas in the protosolar disk, potentially lowering the gas density below that required for efficient chondrule formation by planetesimal bow shocks. Here we propose an alternative mechanism that can occur in a gas-depleted environment: heavy bombardment of eccentric planetesimals by debris dust. After Jupiter formed in the protosolar disk, the region interior to its orbit became gas-depleted, leading to the formation of a geometrically thin debris-dust layer. When planetesimals enter the dust layer at high speed, large quantities of molten silicate droplets are produced. These droplets cool and solidify into chondrules and are reincorporated into the dust layer. Using analytical calculations, we find that our model can potentially explain the abundance, formation timing, and mineralogical and chemical characteristics of chondrules. This study links the formation of Jupiter and the accompanying
evolution of the protosolar disk to the origin of terrestrial
planets, asteroids, and meteorites, thereby offering a new framework for the formation of the Solar System.
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All authors Sota Arakawa, Hidekazu Tanaka, Toshihiko Kadono, Takayuki Ushikubo, Makiko Nagasawa, Hiroshi Kobayashi
Earth and Planetary Astrophysics
Stability Mapping of the New Uranian Moon S/2025 U1 with Updated Masses for Cordelia, Ophelia, and Cressida
J. Xavier, A. Amarante, S. Giuliatti Winter et al. (+1 more)
We investigate the dynamics of Uranus's inner satellite system considering three recent updates: the inclusion of the new moon S/2025~U1, revised mass estimates for Cordelia, Ophelia, and Cressida, and updated zonal harmonic coefficients (J$_2$, J$_4$, and J$_6$). Using numerical integrations, mean-motion resonance analysis, and Frequency Map Analysis (FMA), we explore their impact on orbital stability. For the first time, we analyze the dynamics of the newly discovered moon S/2025~U1 and find that it follows a stable orbit, exhibiting smooth variations in its orbital elements over 250,000~years. Depending on the adopted radius, the gravitational influence of S/2025~U1 on the surrounding region is more compatible with a body of approximately 5-7 km radius, producing
diffusion maps associated with a regular orbital
evolution. Furthermore, the case $R = 7$ km shows a reduction in the
diffusion of neighboring satellites, suggesting a possible local stabilizing effect on the system's orbital
evolution. We also identified inner and outer regions of low
diffusion around its orbit, suggesting that the dynamical environment is compatible with survival of coorbital particles or additional small satellites. In contrast, very high radius values, particularly $R = 20$ km, tend to increase
diffusion among neighboring satellites, making this scenario less compatible with a dynamically stable orbital configuration. We further explore the survival of hypothetical satellites near S/2025~U1. Our results show that bodies with masses up to $3\times$ that of S/2025~U1 can remain stable in both the interior (between S/2025~U1 and Ophelia) and the exterior (between S/2025~U1 and Bianca) of its orbit. Finally, Cressida, Desdemona, Juliet, and Portia are most sensitive to updated parameters. Most resonances circulate, while Belinda-Perdita 44:43 confines the system with reduced libration amplitude.
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All authors J. Xavier, A. Amarante, S. Giuliatti Winter, A. Ferreira