Earth and Planetary Astrophysics
Constraining Tidal Migration with the Hot Jupiter Population
Linhao Ma, Yubo Su, Samuel W. Yee et al. (+3 more)
Hot Jupiters with orbital periods shorter than a few days have probably been affected by tidal orbital migration. We develop an analytical framework for constraining tidal migration from the present-day hot Jupiter period distribution, taking into account the uncertain rate and period distribution of hot Jupiters produced by mechanisms such as high-eccentricity migration or disk-driven migration. Assuming the tidal migration timescale is proportional to $P^{\chi_\tau}$, solutions with $\chi_\tau \simeq 3, 1.7,$ and 5.6 are all compatible with the present-day period distribution. The $\chi_\tau \simeq 3$ solution is consistent with
equilibrium tides with suppression of dissipation at short periods, and implies that newly circularized hot Jupiters have periods concentrated near $3-4$ days, as predicted in some high-eccentricity migration models. The $\chi_\tau \simeq 1.7$ solution is also compatible with the $3-4$ day peak but has no clear counterpart in existing tidal theories and is more finely tuned. The $\chi_\tau \simeq 5.6$ solution is compatible with enhanced short-period
equilibrium tidal dissipation or weakly nonlinear
gravity-wave dissipation, but requires circularization at unexpectedly short periods. Thus, we find the model with $\chi_\tau \simeq 3$ most appealing. Transit timing of individual systems and observational constraints on the rate of hot Jupiter engulfment provide additional constraints, which are presently inconclusive but should improve with future data. Improved measurements of the occurrence of short-period
planets as a function of
planet mass and system age could also help to sharpen the constraints on tidal migration.
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All authors Linhao Ma, Yubo Su, Samuel W. Yee, Caleb Lammers, Eliot Quataert, Joshua N. Winn
Earth and Planetary Astrophysics
Fast and Furious: Long-term orbit integrations with collocation integrator Lobbie
Dmitrii E. Vavilov, Siegfried Eggl and Sarah Greenstreet
Efficient and accurate numerical integration methods are fundamental to studying long-term solar system dynamics, where numerical errors can accumulate over billions of orbital periods. In this work, we investigate the performance of our modification of Lobbie, a Lobatto collocation integrator for long-term simulations of the Solar System. We compare Lobbie against the widely used WHFast symplectic integrator and the high-order adaptive collocation integrator IAS15 implementations in the Rebound package. The performance of the integrator is evaluated using five
benchmark problems: a circular two-body orbit integrated over 100 Myrs, two-body orbits with eccentricities up to 1-10^{-6} to test the adaptive step size control during repeated close encounters, the full eight-
planet Solar System integrated over 100 Myrs, the four giant
planets integrated over 10 Gyrs, and the eight-
planet Solar System together with 50 asteroids on Aten-like orbits integrated over 1Myr to test the integrator's consistency in a chaotic, close-encounter-rich environment. Across all tests, Lobbie demonstrates excellent long-term stability and competitive computational performance. For full Solar System integrations, Lobbie achieves relative energy conservation at the level of 10^{-14} while outperforming IAS15 in computational efficiency and approaching the speed of WHFast at comparable accuracy. In the Solar System plus asteroids test, Lobbie also keeps different realizations of Jupiter's orbit consistent with each other to within about 1.5 km after 1 Myr of integration, two orders of magnitude better than IAS15, being twice faster. Our results demonstrate that Lobbie provides a powerful universal alternative to traditional symplectic mappings or Gauss-Radau collocation methods for long-term dynamical simulations in celestial mechanics.
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Earth and Planetary Astrophysics · Cross-listed from astro-ph.SR
UX Men: Detached Eclipsing Binary as a Benchmark Candidate
Ganesh N. Pawar, Krzysztof G. Hełminiak, Nicola J. Miller et al. (+5 more)
We present ultra-precise fundamental parameters for the detached eclipsing binary UX Men based on 31 TESS sectors ($\sim$882 d) and radial velocities from HARPS, FEROS, CORALIE, and UCLES. The light curves were detrended for spot-induced variability and modelled independently with JKTEBOP and ALLESFITTER, while radial velocities were extracted via TODCOR and fitted with a Keplerian orbit. Spectral disentangling yielded individual component spectra analysed with iSpec to determine $T_{\rm eff}$ and $\mathrm{[M/H]}$. Multi-band photometry was used to determine the fluxes, flux ratios and ultimately to measure photometric $T_{\rm eff}$. We obtain the masses $M_{\rm A}$ = $1.2300 \pm{0.0012}$ M$_{\odot}$, $M_{\rm B}$ = $1.1946\pm{0.0012}$ M$_{\odot}$ and radii $R_{\rm A}$ = $1.3605\pm{0.0031}$ R$_{\odot}$, $R_{\rm B}$ = $1.2801\pm{0.0069}$ R$_{\odot}$ with sub-percent precision. Uncertainties were found to be dominated by systematic effects coming from (weak) stellar activity. $T_{\rm eff,A}$ = $6302\pm{77}$, $T_{\rm eff,B}$ = $6292\pm65$ &
Metallicity estimates are $[M/H]_{\rm A} = 0.02\pm{0.13}$ dex and $[M/H]_{\rm B}= 0.07\pm{0.10}$ dex. Isochrone fitting yields a consistent age of $\tau$ = $2.75\pm{0.13}$ Gyr. The system exhibits a $\sim$ 673-day periodicity in eclipse-timing variations, likely due to stellar activity, with no evidence for a third body. Results are independent of the modelling code used, but without proper treatment of activity-induced systematics the uncertainties would be underestimated. UX Men is a high-precision
benchmark binary providing stringent tests of stellar models and a robust calibration source for PLATO. Expanding the sample of well-characterised detached eclipsing binaries will strengthen the empirical foundations for stellar physics and the calibration of future photometric missions
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All authors Ganesh N. Pawar, Krzysztof G. Hełminiak, Nicola J. Miller, Frédéric Marcadon, Ayush Moharana, Tilaksingh B. Pawar, Anish Kalsi, Maciej Konacki
Earth and Planetary Astrophysics
WASP-43b TESS Phase Curve Mapping: Evidence for a Hot Interior
Maura Lally, Ryan C. Challener, Elspeth Lee et al. (+1 more)
Phase-curve mapping probes various atmospheric properties depending on wavelength: thermal phase curves are dominated by atmospheric emission, while visible and near-infrared phase curves include reflected light. The measured planetary phase curve offset–the longitudinal offset of the hemisphere of peak brightness from the substellar point–is therefore sensitive to differing atmospheric processes in emission-dominated vs. reflection-dominated bands. In particular,
planets with partial western-dayside reflective cloud coverage show a westward reflected-light phase-curve offset relative to the thermal wavelengths. In this work, we analyze five sectors of TESS phase curve observations of the hot Jupiter WASP-43b and compare to previous published multi-band analyses to investigate dayside cloud coverage. We measure a mid-eclipse depth of 130 $\pm$ 34 ppm, indicating excess TESS planetary brightness above expectations based on observed and modeled thermal emission. Attributing this excess flux to reflection, we estimate a low
geometric albedo of $A_g$ $\approx$ 0.05 - 0.10. These findings support previous conclusions that WASP-43b lacks any significant cloud coverage on its dayside. Phase-curve mapping reveals a large eastward phase curve offset of 44 $\pm$ 18 degrees, significantly eastward of offsets measured at longer wavelengths with JWST, providing evidence for a cloud-free dayside. Both the detection of excess emission in the TESS band and the large measured eastward phase-curve offset support the conclusion that WASP-43b has a hot deep atmosphere that is probed at short wavelengths.
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All authors Maura Lally, Ryan C. Challener, Elspeth Lee, Nikole Lewis
Earth and Planetary Astrophysics
Sorting a mess I: Addressing velocity-axis correlation of cross-correlation functions. A census of atomic and ionised species in KELT-9b's atmosphere
Nicholas W. Borsato, Brian Thorsbro, Jens Hoeijmakers et al. (+3 more)
Ultra-hot Jupiters (UHJs) are the most extreme class of close-in gas giants. We combine 13 transit observations of KELT-9b from six high-resolution spectrographs spanning 316-960 nm to conduct a census of atomic and ionised species in its atmosphere using cross-correlation. We introduce an agnostic strategy to mitigate velocity-axis correlation bias in parameter uncertainties. A forward model of the cross-correlation function (CCF) and a Monte Carlo bootstrap of flux uncertainties measure the CCF-derived velocity profiles of individual species and assess their time dependence. The stellar reference frame is determined, yielding Vsys = -17.99 +/- 0.04 km s^-1 and v sin i = 110.54 +/- 0.05 km s^-1. All previously reported species are recovered except Tb II; the combined analysis detects 29 species, including C I, Si I, K I, V II, Co I, Zr II, La II, Pr II, and Nd II. All 29 recovered species exceed the conventional 5 sigma threshold in the bootstrap Mahalanobis significance test. The collective Doppler shifts show a blueshift of Delta Voffset = -8.02 +/- 0.17 km s^-1 relative to the stellar rest frame, indicating a net day-to-night wind, with no explicit time dependence when all species are homogenised. These results provide a catalogue of detections and retrieved Doppler parameters for a companion study of KELT-9b.
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All authors Nicholas W. Borsato, Brian Thorsbro, Jens Hoeijmakers, Daniel B. Zucker, Stefan Pelletier, Bibiana Prinoth
Earth and Planetary Astrophysics
Energy deposition in planetary and exoplanetary atmospheres induced by cosmic rays
Jesse Polman and Ingo Leya
Cosmic rays can significantly alter the abundances of certain species in the upper layers of planetary atmospheres, especially in terms of their biosignatures. To fully understand the extent of this effect, it is essential to accurately model the interactions of
cosmic rays with planetary
magnetic fields. We used the CosmicTransmutation code to study the effect of a planetary
magnetic field on the flux of galactic
cosmic rays and stellar energetic particles. We found that both particle sources are significantly affected by
magnetic fields, even though the effects are different due to the varying energy ranges that characterize each source. The stellar energetic particle energy flux is significantly higher for an Earth-like
planet with no
magnetic field, but with a
magnetic field of 30\,$\mu$T or higher, the energy flux of the two sources becomes comparable. We find that the atmospheric pressures the
cosmic rays reach are significantly lower than those found in previous studies using simpler models and that the effect of the atmospheric composition on this outcome is small. We found similar results using the model for the
exoplanet K2-18b, even though the radius is significantly larger than Earth's. Because the two
cosmic ray sources cover different energy ranges and are affected by the
magnetic field in different ways as a result, both sources should be considered. Future studies should focus on combining an accurate modelling procedure of the interaction between
cosmic rays and planetary
magnetic fields with atmospheric chemistry models. This will require general circulation models to capture the latitudinal and longitudinal dependencies in full.
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Earth and Planetary Astrophysics · Cross-listed from astro-ph.IM
Small-Body Science with the Nautilus Space Observatory: From Cislunar Space Resilience to Mapping the Kuiper-Belt-to-Oort-Cloud Transition
J. de Wit, A. Y. Burdanov, P. McGill et al. (+3 more)
A new generation of space-based observatories can transform small-body science from the local Earth-Moon environment to the Solar System's dynamical frontier, where planetary control gives way to Galactic tides and stellar encounters. Mapping this frontier would reveal how planetesimals were scattered during giant-
planet formation, how many primordial bodies survived in distant reservoirs, and whether large objects remain undiscovered in the inner Oort Cloud. At the same time, meter- to decameter-scale natural objects traversing the Earth-Moon system are frequent but poorly characterized. As human and robotic activity expands, their operational relevance depends not simply on abundance but on object size, encounter geometry, exposed infrastructure, warning time, and available response. Lunar impacts and impact-generated ejecta provide one class of events, while fading objects with unresolved Earth or lunar impact probabilities provide another. Here, we explore a two-layer small-body program combining a 4.0 m-diameter Nautilus Quattro Imaging (NQI) unit with an illustrative distributed cislunar layer of ~50 cm-class wide-field optical
telescopes. The cislunar layer would characterize the nearby natural-object population, support rapid classification and selective custody of high-interest objects, and monitor lunar impacts and ejecta; the NQI deep-search layer would provide precise astrometry and synthetic tracking for faint-object recovery and distant-Solar-System surveys. Together, the two layers would constrain the small-impactor population, resolve fading planetary-defense targets, and survey the distant Solar System to Vmag ~30, enabling tests of the Kuiper-Belt-to-Oort-Cloud transition while advancing Earth-Moon space resilience.
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All authors J. de Wit, A. Y. Burdanov, P. McGill, D. Apai, S. N. Hasler, S. Cambioni
Earth and Planetary Astrophysics
A Candidate Innermost Fifth Planet In the HR 8799 System Revealed By JWST NIRISS Aperture Masking Interferometry
Jayke S. Nguyen, Louis Desdoigts, Alexandra Z. Greenbaum et al. (+20 more)
We detect a candidate fifth
planet in the HR 8799 system, directly imaged with the JWST/NIRISS Aperture Masking Interferometer (AMI). The detected source lies just above a $3\sigma$ contrast curve at a contrast of $\sim2\times10^{-4}$ in the F380M filter at a projected separation of $\sim150$ mas, corresponding to a few-to-several Jupiter mass
planet at an orbital radius of $\sim 7$au. The separation of the candidate is compatible with absolute proper-motion constraints from Gaia and Hipparcos assuming it is bound, while its orbital position lies near a stable orbital solution of a fifth
planet in a 3:1 mean motion resonance with
planet e. This detection was made possible by a new JWST/NIRISS AMI data pipeline that reaches the
photon noise limited potential of AMI by accounting for the optical and electronic systematics that limited sensitivity in prior analyses. Confirmation of this candidate would make HR 8799 the first directly imaged five-
planet system and provide insight into the orbital dynamics and the dynamical
evolution of planetary systems with widely-separated gas giants.
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All authors Jayke S. Nguyen, Louis Desdoigts, Alexandra Z. Greenbaum, Benjamin J. S. Pope, Max Charles, Quinn M. Konopacky, Kaitlyn Hessel, Dori Blakely, Matthew De Furio, Clarissa R. Do Ó, René Doyon, Doug Johnstone, Jens Kammerer, David Lafrenière, Bruce A. Macintosh, Michael R. Meyer, Eric L. Nielsen, Anne E. Peck, William Roberson, Anand Sivaramakrishnan, Peter Tuthill, Thomas Vandal, Marie Ygouf
Earth and Planetary Astrophysics
From spirals to rings: dust dynamics in gravitoturbulent protoplanetary discs after late infall
Clément Baruteau, Steven Rendon Restrepo, Gaylor Wafflard-Fernandez et al. (+7 more)
Substructures appear to be a common trait of all extended protoplanetary discs. They are found notably in discs still surrounded by ambient, possibly infalling material. In this study, we revisit the observational signatures of gravitational instability (GI) in the dust and gas emission of protoplanetary discs. We focus on discs undergoing a short-lived episode of late infall that triggers spirals via GI, in order to investigate the long-term dynamics of millimetre-sized dust. We performed 2D hydrodynamical simulations modelling gas and millimetre-sized dust in a self-gravitating disc, with a simplified treatment of stellar irradiation and infall. Results were post-processed by 3D radiative transfer calculations. During infall, GI sets in and the disc develops a gravitoturbulent state characterised by the continuous formation of spirals. Shortly after infall ends, the millimetre-sized dust remains well coupled to the gas, and the dust emission exhibits large-scale spirals in both near-infrared scattered light and continuum emission. Even long after infall has ceased, two-armed spirals are persistently excited by GI in specific regions of the disc. Their dissipation entails the formation of multiple long-lasting pressure maxima, which can be viewed as vestiges of shocks induced by the spirals. They form persistent dust rings that are more or less axisymmetrical. Consequently, once late infall ends, a massive disc can gradually evolve from a disc with spirals in the continuum into one featuring multiple, potentially lopsided bright rings in the continuum. In near-infrared scattered light, the disc initially displays multiple spirals during infall or shortly after it ceases, before ultimately exhibiting multiple rings. The persistent excitation of spirals implies, however, that the residual line-of-sight velocity, derived from line emission, shows large-scale spirals across the disc.
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All authors Clément Baruteau, Steven Rendon Restrepo, Gaylor Wafflard-Fernandez, Sebastián Pérez, Zhaohuan Zhu, Hans Baehr, Farzana Meru, Jean-François Gonzalez, Sergei Nayakshin, Sahl Rowther
Earth and Planetary Astrophysics · Cross-listed from astro-ph.SR
Untangling EIT Waves: What a Measured Speed Actually Traces
Olena Podladchikova
Nearly three decades after the first SOHO/EIT observations, reported EUV-wave speeds still range from a few tens to more than 1000 km/s. This Perspective asks what those numbers actually trace. A measured image speed depends on passband and line-of-sight weighting, cadence, difference imaging, the selected crest or leading edge, propagation sector, fitted interval, and projection geometry. Same-event comparisons quantify this observation-operator effect. In events common to the Nitta and Muhr analyses, early or fastest-sector measurements were typically higher; five of six directly shared events differed by about 30%. For 19 May 2007, the 171 Angstrom peak speed was 475 +/- 47 km/s, compared with 238 +/- 20 km/s in 304 Angstrom, while the 171 Angstrom cadence was four times faster than the 195 Angstrom cadence. A sampling audit of the 1 April 2017 SWAP event shows that a repeated speed near 834 km/s is almost exactly one 91.6-Mm radial ring per 110-s image interval. In a reconstructed 3 April sector, AIA 171 Angstrom gives about 405 km/s, compared with the published SWAP mean of 484 km/s; an independently selected AIA 193 Angstrom ridge gives about 250 km/s under strongly shortened exposures. Such differences are not automatic evidence for different MHD modes. A same-event energy pilot separates compact-source heating, dimming/ejecta, and one weak-compression front segment. The current data do not justify a universal power law, but define a falsifiable question: is the fraction of released energy carried by the front scale invariant from compact quiet-Sun events to global waves and shocks? Establishing this dependence would show which eruption scales can contribute materially to coronal heating.
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Earth and Planetary Astrophysics
Physics-Informed Multi-Task Surrogate Model for the Martian Nightside Thermosphere
Sergey Nikiforov
Modeling the Martian nightside thermosphere remains challenging due to sparse in situ sampling and strong coupling among transport,
magnetic, and seasonal processes. Purely data-driven models can produce non-physical artifacts, such as density inversions, in poorly sampled altitude regimes. We present a multi-task physics-informed neural network that simultaneously predicts the base-10 logarithmic densities of four neutral species (O, CO$_2$, N$_2$, and Ar) using more than a decade of MAVEN/NGIMS observations (MY 32-38, 2014-2025). A shared backbone learns a common representation of the nightside thermospheric state and branches into species-specific output heads. A weak monotonicity prior is incorporated via automatic differentiation by penalizing positive vertical gradients in logarithmic density. Experiments using an orbit-disjoint train/validation/test split show that physics-informed regularization substantially reduces non-physical inversions while preserving predictive skill and slightly improving it in the best-performing configuration, as measured by RMSE, MAE, and $R^2$. The resulting model provides a computationally efficient surrogate for nightside thermospheric reconstruction with improved vertical consistency.
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Earth and Planetary Astrophysics
Magnetically Driven Obliquity in Circumplanetary Disks and Twisted Bipolar-jet Formation
Raúl O. Chametla, Martin E. Pessah, F. Javier Sánchez-Salcedo et al. (+4 more)
Circumplanetary disks (CPDs) regulate gas
accretion onto forming giant
planets and provide the environment in which their satellites may form. We use high-resolution, global three-dimensional simulations to investigate the early formation, orientation, and outflows of a CPD around a Jupiter-mass
planet embedded in a turbulent magnetized protoplanetary disk. Within a locally isothermal, ideal-MHD framework, we evolve disks threaded by net vertical
magnetic fields, corresponding to initial
plasma parameters $875\leq\beta\leq3500$, until magnetorotational-instability-driven
turbulence is established before inserting the
planet. We also perform a hydrodynamic control simulation. In the most strongly magnetized model, with $\beta=875$, the CPD forms already highly inclined and reaches a maximum tilt of approximately $87^\circ$. By contrast, the hydrodynamic CPD and the MHD models with $\beta\gtrsim1000$ remain nearly coplanar. A control simulation in which the
planet is inserted before global MRI
turbulence develops also remains coplanar, despite producing local
turbulence and bipolar outflows. The large tilt is therefore associated with the pre-existing global turbulent state and its evolved velocity and toroidal
magnetic-field structure, although our current diagnostics do not distinguish between a direct
magnetic torque and the
accretion of misaligned angular momentum. All MHD models launch bipolar outflows; in the highly tilted case, these develop a curved, helical morphology that persists until the end of our short-term simulations. These results identify pre-existing global magnetized
turbulence as a viable route to generating strongly inclined CPDs and twisted planetary outflows.
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All authors Raúl O. Chametla, Martin E. Pessah, F. Javier Sánchez-Salcedo, David Vokrouhlický, Mauricio Reyes-Ruiz, Ondrej Chrenko, Alessandro Morbidelli
Earth and Planetary Astrophysics
Can the Long-Term Impact of Stellar M-Dwarf Flares Alter the Spectral Features of a Giant Gaseous Exoplanet?
Amy Louca, Shang-Min Tsai and Yamila Miguel
In this work, we model the long-term impact of recurrent stellar
flares on the atmospheres of metal-rich gaseous
exoplanets. Using synthetic
flare spectra from a fiducial
flare model integrated with a photochemical kinetics code, we track the changes in atmospheric composition with time. We further analyze the spectral variability by feeding these abundance profiles into a radiative transfer code at various time steps. Our simulations showed variability and persistent changes in key atmospheric species, such as CH4, CO2, and SO2, when compared to their quiescent state. Extreme
flare events cause rapid depletion of molecules in the upper atmosphere and a temporary disappearance of spectral features, especially the SO2 feature at 7-8 microns, which shifted by about 75 ppm. Many species did not fully return to their quiescent state after
flares, resulting in lasting changes in abundance, especially for SO2 and CO2, key species when inferring the atmospheric metallicty. We also explored the cumulative effects of recurrent
flares, showing that species like H2O and CH4 followed a decreasing abundance trend, with half-lives of around 28 to 31 years. These results indicate that
flare activity plays a significant role in shaping both the short- and long-term atmospheric composition and spectral features of giant gaseous
exoplanets orbiting M-dwarf
stars, underscoring the need to account for stellar activity when characterising such atmospheres. Our findings also highlight that the atmosphere of the modelled
planet is not static, suggesting that a probabilistic approach to atmospheric abundances may be more appropriate than static
retrievals, particularly for gaseous
planets orbiting active
stars.
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Earth and Planetary Astrophysics
JWST-SUPER I: New insights into irradiated warm Neptunes atmospheres from MIRI observations of HD 106315 c
A. Dyrek, R. Waters, S.-M. Tsai et al. (+17 more)
Sulphur-bearing molecules have recently emerged as powerful tracers of atmospheric photochemistry in
exoplanets observed with JWST. In several warm giant
planets, SO$_2$ has been detected as a product of UV-driven chemical processing, suggesting a close connection between stellar irradiation, atmospheric
metallicity, and sulphur chemistry. Whether these trends extend to Neptune-mass
planets orbiting hotter
stars remains largely unexplored. We investigate the atmospheric composition of the warm Neptune HD 106315 c, a Neptune-mass
planet orbiting an F-type host
star and subjected to a strong ultraviolet (UV) irradiation environment. Here, we report the low-resolution transmission spectrum between 5 and 12 $\mu$m of HD 106315 c obtained with the MIRI Low-Resolution Spectrometer on-board JWST. Our work also includes re-analysis of archival data from HST WFC3 G141 mode of HD 106315 c, as well as contemporaneous XMM and Swift monitoring of the
star in the UV and X-ray wavelength ranges. Together with the archival HST WFC3 data, we detect H$_2$O and find tentative evidence for NH$_3$, retrieving abundances of $\log_{10}$(H$_2$O)$=-1.40^{+0.40}_{-0.74}$ and $\log_{10}$(NH$_3$)$=-2.47^{+0.57}_{-0.89}$, together with an isothermal terminator temperature of $747^{+150}_{-155}$ K. We place stringent upper limits on CH$_4$, SO$_2$, and CS$_2$, finding no robust evidence for any sulphur-bearing species despite the intense irradiation received by the
planet. The inferred water abundance implies a strongly metal-enriched atmosphere. Elevated intrinsic temperatures can reconcile the non-detections of CH$_4$ and CS$_2$ through carbon–sulphur coupling, while the absence of SO$_2$ points toward a reduced atmospheric sulphur inventory or a near-solar to mildly enhanced C/O ratio, and places HD 106315 c near the transition between sulphur-rich and sulphur-poor chemical regimes.
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All authors A. Dyrek, R. Waters, S.-M. Tsai, M. Holmberg, B. Edwards, J. Pye, M. Güdel, N. Crouzet, R. van Gompel, J. Polman, F. Ardevol Martinez, D. Barrado, W. De Gruijter, Th. Henning, S. Kendrew, N. Khorshid, Y. Miguel, M. Min, M. Morales-Calderon, M. Topinka
Earth and Planetary Astrophysics
Hybrid Spin-Orbit Tomography for Earth-like Planets: Simultaneous Mapping of Static Surfaces and Dynamic Clouds from Multicolor Light Curves
Atsuki Kuwata and Hajime Kawahara
Photometric variability of directly imaged
exoplanets encodes information on both persistent surface features and time-variable phenomena such as clouds. We present Hybrid
Spin-Orbit
Tomography, a method that simultaneously retrieves multiple static components and a single dynamic component, together with their reflection spectra, from multiband photometric variability. The method integrates spectral unmixing and dynamic
spin-orbit
tomography by introducing a time-dependent component into the forward model. We employ sparse regularization for static surface distributions, volume regularization for reflection spectra, and a Kronecker-sum kernel regularization for the dynamic component. Applying the method to a toy Earth model, we successfully recover static surface distributions together with a single time-dependent cloud component. Furthermore, we apply the method to DSCOVR/EPIC observations of Earth and retrieve a dynamic component consistent with real cloud distributions, together with components broadly interpretable as oceans, vegetation, and land surfaces. Relative to static
spin-orbit unmixing, the hybrid model substantially reduces the residual scatter of the multiband light curves, demonstrating that explicit treatment of dynamic components improves global mapping from color variability. These results provide a step toward the simultaneous
retrieval of static and dynamic planetary components, while highlighting the need for more physical cloud-surface masking models and uncertainty quantification.
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Earth and Planetary Astrophysics · Cross-listed from astro-ph.SR
Automated Detection of Double-Lined Spectroscopic Binaries in High-Resolution Spectra and a Probabilistic Analysis of Stellar Multiplicity
William B. Salazar, Steven Giacalone and Andrew W. Howard
The characterization of Sun-like
stars, including determining whether those
stars are single or have stellar companions, has become increasingly important for missions seeking
planets beyond the Solar System. With upcoming missions like the Habitable Worlds Observatory (HWO) on the horizon, vetting
stars for binarity and confirming potential targets as viable is essential precursor science. In this paper, we present an automated
algorithm that searches for double-lined spectroscopic binaries (SB2s) in high-resolution spectra. Using MOLUSC, we simulate realistic stellar populations to quantify the capability of
algorithm for detecting stellar companions around nearby
stars, with potential applications to HWO target
stars and Gaia DR4
planet-host candidates. In addition, we explore how the detection rate is influenced by complementary observations like high-resolution adaptive optics imaging and time-series radial velocities. We find that our SB2 detection
algorithm alone can rule out 46.1% of stellar-mass companions. High-resolution adaptive optics alone rules out 79.6% of stellar companions. Radial velocity surveys alone ruled out 98.4% and 98.7% for 5-year and 10-year surveys, respectively. When all three methods are combined, the probability of a typical nearby
star having a stellar companion is <1%. The combination of the methods allows us to better understand and resolve target lists for future surveys.
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Earth and Planetary Astrophysics · Cross-listed from astro-ph.IM
A pilot study on the CSST astrometric capability: Detecting astrometric binaries with Gaia synergy via simulated data
Shangyu Wen, Shilong Liao, Zhaoxiang Qi et al. (+8 more)
Context. The China Space-station Survey
Telescope (CSST) will provide deep, wide-field epoch astrometry during its 10-year mission. Astrometric binary orbits constrain the masses of stellar and compact-object components. Orbital recovery depends on astrometric precision and temporal coverage. Combining CSST and Gaia data extends the baseline and improves binary detection. Aims. We evaluate CSST, Gaia, and joint astrometry for binary-candidate selection and 12-parameter (12p) orbit fitting at faint magnitudes ($g>17.8$). We also test how regular CSST cadences affect the yield of 12p fits satisfying our criteria. Methods. We constructed a mock catalog, simulated CSST and Gaia epoch astrometry, and fitted five-parameter (5p) single-
star models to derive astrometric diagnostics, proper-motion anomaly features, and observational-sampling features. A four-stage histogram-based gradient-boosting classifier used these features to select candidates for 12p orbit fitting and assessment. Results. On the independent test set, the classifier reaches a precision of 0.802 and a recall of 0.181 among eligible true binaries. In the scenario-specific fitted samples, joint astrometry raises the fiducial fraction from 6.76% for Gaia alone to 10.46%; for fitted binaries with $P_{\rm true}>15{\rm yr}$, it rises from 2.37% to 6.78%. The current CSST schedule yields few fiducial fits, while idealized regular cadences increase the yield mainly at $g\lesssim21$. Conclusions. In the simulation, joint CSST and Gaia epoch astrometry yields higher fractions of fitted unresolved binaries satisfying the stated criteria than Gaia-only solution. A practical strategy is to select candidates from 5p diagnostics and astrometric anomalies, obtain more regular CSST follow-up observations, and then fit 12p orbital models and apply the selection criteria.
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All authors Shangyu Wen, Shilong Liao, Zhaoxiang Qi, Zhensen Fu, Xiyan Peng, Ye Ding, Qiqi Wu, Qi Xu, Xun Sun, Keyu Zhu, Yong Yu