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Physics Astrophysics Earth and Planetary Astrophysics

astro-ph.EP Watch Earth and Planetary Astrophysics

Saturday 15 August

Earth and Planetary Astrophysics

Scaling of microcraters with molten rims derived from laser-induced cratering experiments

S. Sato, H. Shibayama, K. Nagai et al. (+1 more)

Microcraters with molten rims are widely observed in returned samples from the Moon and asteroids. These features reflect the conditions of small-scale impact events, but the impact velocities required for their formation are not well understood. In this study, we use well-controlled laser irradiation on rock surfaces as an experimental analog to investigate the formation of these molten-rim craters. Specifically, we derive a scaling relation between crater volume, total irradiation energy, and energy loss associated with thermal diffusion. The experimental results indicate that molten-rim structures of microcraters can be formed in the range of $10^2$–$10^3$~m/s impact velocity. This value is consistent with some previous studies which suggested that the origin of microcraters is secondary impact events. These findings provide experimental constraints on the formation mechanisms of molten-rim microcraters and offer a new perspective on impact processes recorded on planetary surfaces. The estimated result is also consistent with the impact velocity required to produce the observed wavy rim protrusions due to a Rayleigh-Taylor hydrodynamic instability ($\sim 10^2$~m/s).
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All authors S. Sato, H. Shibayama, K. Nagai, H. Katsuragi

Friday 14 August

Earth and Planetary Astrophysics

The Enceladian crater production function

E. W. Wong, S. C. Werner, M. R. Kirchoff et al. (+1 more)

Interpreting Enceladus's past and present surface history and interior state remains challenging, owing to uncertain prescription of its impact bombardment history and limited interpretation of its crater statistics. Further progress in understanding its evolutionary history can be achieved with an improved crater chronology model and a thorough assessment of Enceladus's surface. Here we present the first step in the form of a comprehensive, global crater catalogue with geomorphology survey for Enceladus. From our dataset we build the crater production function (CPF), which is the underlying, unmodified crater size-frequency distribution of the satellite surface, assuming no subsequent modification. We obtained the CPF with a data-driven approach; therefore it makes no assumptions about the impactor source population or planet evolution models or the timing of impact. We fit the CPF with a high-order polynomial as is customary for the Moon and Mars, capturing the slope variations across different crater diameter ranges. The Enceladian CPF generally has a steeper cumulative slope than that of the Moon and Mars for small crater diameters D_cr < 10 km, as well as that of the size-frequency distribution of trans-Neptunian objects. This CPF serves as a critical observational input for an Enceladian crater chronology model, enabling the conversion of crater densities into absolute surface ages. Extending the crater cataloguing and CPF derivation of this study to other Saturnian satellites will determine whether the Enceladian CPF is unique; a shared CPF would indicate a common impactor population, providing observational constraints on the size-frequency distribution of small bodies in the outer Solar System.
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All authors E. W. Wong, S. C. Werner, M. R. Kirchoff, R. Brasser

Earth and Planetary Astrophysics

Hydrogen Engulfment into Sub-Neptune Cores through Magma Ocean Convective Surface Renewal

Edward D. Young

A convective surface renewal explanation for ingassing of hydrogen from H2-rich envelopes into molten cores of growing planets is presented, with particular application to sub-Neptunes. The ingassing of hydrogen occurs at a moving front comprising the upper boundary of the magma ocean that engulfs hydrogen from the envelope above as it moves. The mechanism of engulfment is surface renewal as the upper diffusive boundary layer is diluted by convection. Surface renewal results in ingassing even where the stabilizing buoyancy of the low-density hydrogen neutralizes the destabilizing thermally-driven buoyancy. It is ultimately driven by cooling. Beginning during the gaseous disk phase, when hydrogen is effectively available in infinite supply, sub-Neptunes can acquire enough hydrogen to permit global core-envelope equilibrium. The structures are therefore consistent with hydrogen-rich, supercritical magma oceans overlain by hydrogen-rich envelopes. The process of surface renewal has implications for other magma ocean - atmosphere interactions in general.
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Earth and Planetary Astrophysics · Cross-listed from astro-ph.SR

A chemo-dynamical search for planet-candidate hosts of possible extragalactic origin

Sun Tiancheng, Chen Xunzhou, Xiang Maosheng et al. (+2 more)

To date, all known exoplanetary systems have been identified around stars currently residing in the Milky Way, whereas planets formed in external galaxies remain largely unexplored. Such systems would offer a unique probe of planet formation in galactic environments distinct from the Milky Way. We combine a literature-compiled sample of Kepler, K2, and TESS planet-candidate host stars with Gaia DR3 astrometry and radial velocities, and incorporate metallicities and [Mg/Fe] abundances from the LAMOST DR9 DD-Payne catalogue, to search for candidate accreted-halo planet hosts. We identify 11 planet-candidate hosts with halo-like kinematics, five of which have reliable chemical abundance measurements. Among these, four systems exhibit low metallicities ([Fe/H]<-0.7) and low [Mg/Fe] ratios that are inconsistent with the canonical Milky Way thick-disc sequence, indicative of enrichment histories characteristic of accreted dwarf galaxies. We further carry out a uniform false-positive assessment using Gaia RUWE, Gaia DR3 neighbourhood checks, odd–even transit-depth comparisons, secondary-eclipse searches, independent BLS period recovery, and comparison with ExoFOP and available follow-up information. This vetting identifies EPIC~211407755 and TIC~239541449 as the most plausible, although still unvalidated, planet-candidate systems. TIC~293432942 is more likely associated with a blended or otherwise binary-related false positive, whereas TIC~184739529 remains a high-risk giant-companion candidate whose planetary nature is uncertain. If confirmed, EPIC~211407755 and TIC~239541449 would suggest that planetary systems can form in dwarf-galaxy environments and subsequently survive accretion into the Milky Way.
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All authors Sun Tiancheng, Chen Xunzhou, Xiang Maosheng, Zhou Jianzhao, Lu Zixuan

Earth and Planetary Astrophysics · Cross-listed from physics.ao-ph

Altitude-Dependent Near-Source Spectral Filtering of Meteor Infrasound Above 80 km and Consequences for Period-Based Energy Estimates

Elizabeth A. Silber, Igor P. Chunchuzov, Oleg E. Popov et al. (+1 more)

Infrasound signal period is widely used as a proxy for source energy in bolide studies, but the reliability of period-yield relations for small, high-altitude regional meteors has not been systematically evaluated. We analyze 90 infrasound detections from well-constrained regional meteoroid events (source altitudes 20-111 km, ranges 47-268 km) and demonstrate a strong, monotonic decrease in receiver dominant frequency with increasing source altitude (Spearman r_{s} = -0.629, p = 3.3 x 10^11). No detections above 80 km retain dominant frequencies exceeding 3 Hz, and 75% of detections above 100 km are dominated by sub-1 Hz content. Partial correlation analysis indicates this is primarily an altitude effect, not a propagation distance artifact. Near-source dissipation modeling using the generalized Burgers equation supports a physical mechanism: the exponential increase in kinematic viscosity with altitude drives the acoustic Reynolds number downward, imposing frequency-dependent molecular absorption that selectively attenuates high-frequency content within the first 5 km below the source. Our results suggest that this atmospheric low-pass filter systematically modulates the observed period and can bias period-based energy estimates upward by one to two orders of magnitude for sources above 80-90 km when uncorrected period-yield relations are applied. These findings are relevant to any high-altitude infrasound source, including space debris and controlled reentries.
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All authors Elizabeth A. Silber, Igor P. Chunchuzov, Oleg E. Popov, Sergey N. Kulichkov

Thursday 13 August

Earth and Planetary Astrophysics

Effects of Pebble Accretion Isolation Mass on Observable Exoplanet Properties

Lucas Brefka, Rebekah I. Dawson, Mariah G. MacDonald et al. (+2 more)

The Kepler Mission has discovered a plethora of planetary systems with super-Earth sized planets. These systems exhibit many properties, from widely-spaced planets with non-negligible eccentricities and inclinations, to tightly-spaced, coplanar, and nearly circular multi-planet systems. The observable properties of these systems, such as planet-planet spacings, multiplicity and orbital morphology, can be strongly influenced by the initial conditions of formation. These conditions affect the early growth of planetary embryos in the gas disk phase through pebble and/or planetesimal accretion, which then affects the final growth of planets during the giant impact stage. In this work, we investigate how assumptions of different limiting embryo isolation masses during early stages of planet formation affect the final properties of super-Earth planets within the inner disk, comparing our mock-observed results to each other, as well as to the Kepler sample. We test several models of pebble accretion isolation mass, including pebble isolation, flow isolation, and migration feedback isolation and otherwise adopt the same parameters for the gas disk. We find that while each model can match at least one distribution of observables in the Kepler catalog, they fall short of matching all distributions simultaneously, even with extreme reweighting. Our inability to match all observations suggests that the initial conditions and/or modeled effects in our simulations that we held fixed should be investigated. This exploration sheds light on how planetary systems evolve and the processes that influence the wide range of system parameters we observe today, helping place our own Solar System in context.
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All authors Lucas Brefka, Rebekah I. Dawson, Mariah G. MacDonald, Phoebe Sandhaus, Eric B. Ford

Earth and Planetary Astrophysics · Cross-listed from physics.hist-ph

From the Earth to the Sun

Dieynaba Young

This year marks 360 years since the founding of the French Academy of Sciences. This is the story of the academy's daring 17th century expedition to measure the Earth-sun distance. A truncated version first appeared in National Geographic Magazine; the following is closer to the original draft, with updated information and references.
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Earth and Planetary Astrophysics

The sensitivity of TESS to transiting planets in TOIs with close-in stellar companions

Colin Littlefield, Kathryn V. Lester, David R. Ciardi et al. (+1 more)

High resolution imaging with optical speckle interferometry has revealed that many transiting exoplanet host stars possess close-in stellar companions. The objective of this study is to quantify how the presence of these companions impacts the ability of TESS to detect the transits of small planets. We accomplish this by examining 2052 TESS Objects of Interest (TOIs) that appear to be single-star systems based on speckle interferometric observations as well as 188 TOIs in unresolved ($< 1.2\arcsec$) stellar binaries. For each planet, we take its transit signal-to-noise ratio (SNR), radius, and orbital period from the TOI catalog and, for planets in stellar binaries, we correct the radius for dilution by the companion. By applying a scaling relation to the measured transit SNR of each TOI in our sample, we determine the detectability of transits in each TOI as a function of both planet radius and orbital period. When applied to the full sample, this procedure elucidates the sensitivity of TESS to transiting planets as a function of binarity, host-star spectral type, planet radius, and planet orbital period. These sensitivity grids quantify the bias against the detection of small planets in unresolved binaries by TESS and show that there is a particularly low sensitivity to planets transiting secondary stars in unresolved binaries, especially as the magnitude difference between the stars increases. These sensitivity grids are available for download to facilitate their use in other studies.
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All authors Colin Littlefield, Kathryn V. Lester, David R. Ciardi, Steve B. Howell

Earth and Planetary Astrophysics

No Helium Detected in LHS 1140 b from Four JWST NIRISS/SOSS Transits

Katherine A. Bennett, Carlos Gascón, Jacob Lustig-Yaeger et al. (+13 more)

In the effort to determine which low-mass exoplanets have atmospheres, LHS 1140 b remains one of the most favorable targets. Its large size (5.6 $\rm M_{\oplus}$ and 1.7 $\rm R_{\oplus}$) and relatively long orbital period (24.7 days) imply an atmosphere may be likely, and notably, recent interior models favor either a hydrogen-dominated "mini-Neptune" or a "water world" over a true terrestrial planet. Another possibility is that it has a helium-rich atmosphere. This hypothesis is supported by recent ground-based observations that detected the metastable helium triplet during transit. These observations indicated there may be current helium escape from the planet's upper atmosphere, yet the signal was not detected during a subsequent observation, suggesting time-variable escape. Here we present four observations of LHS 1140 b with JWST NIRISS/SOSS, which covers the metastable helium triplet, obtained between 2023 and 2026. These observations span the epoch of the ground-based measurements, and although none were contemporaneous with the ground-based transits, all four are sensitive to helium absorption at the previously reported level. However, we detect no helium absorption in any visit. We reject the best-fit ground-based model at $>3\sigma$ in each visit, and find no clear trend in mass-loss with time. Our results suggest the reported ground-based detection may be spurious, although variability cannot be excluded if detectable helium absorption occurs in $\lesssim50\%$ of transits. The nature of LHS 1140 b thus remains a mystery until future transmission and emission analyses are complete.
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All authors Katherine A. Bennett, Carlos Gascón, Jacob Lustig-Yaeger, Guangwei Fu, David K. Sing, Kevin B. Stevenson, Jonathan Brande, Munazza K. Alam, Jeff A. Valenti, Mercedes López-Morales, Sten J. Vermeiren, Megan Weiner Mansfield, Sarah E. Moran, Kristin S. Sotzen, Jegug Ih, Sarah Peacock

Earth and Planetary Astrophysics

Strict Limits on Helium Absorption from LHS 1140 b from Four JWST NIRISS Transits

Michael Radica

Orbiting in the habitable zone of its host star, the 1.7 $R_\oplus$, 5.6 $M_\oplus$ planet LHS 1140 b is a target of great interest. Recently Cherubim et al. (2026) published a detection of metastable He escaping from the atmosphere of LHS 1140 b, simultaneously providing the first concrete inference of an atmosphere on this planet and indicating that the atmosphere is He-rich and H-poor as would be expected due to Gyrs of fractionated mass loss. In this work, we analyze four archival transits of LHS 1140 b, spanning Dec 2023 to Jul 2026, taken with the NIRISS instrument on JWST, for evidence of He absorption. Each of the four visits disfavours the presence of He absorption compared to a flat continuum with odds ratios ranging from 3.9–11.6:1. He absorption with an amplitude and width equivalent to that observed by Cherubim et al. (2026) is strongly ruled out by the data with odds ratios from 300–8.6$\times$10$^4$:1 compared to a flat continuum — though it should be noted that none of the JWST transits are contemporaneous with the Cherubim et al. (2026) detection. We also fit the absolute out-of-transit stellar spectra from these four visits, as well as an additional JWST NIRISS transit of planet c, to search for evidence of stellar variability, but find consistent photosphere and herterogeneity parameters in all five datasets. In all, our work provides a set of strict limits on He escape from LHS 1140 b that will be valuable to future studies into the nature and evolution of this intriguing world.
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Earth and Planetary Astrophysics

Stellar tidal systematics in apsidal-motion searches for circumbinary planets: CH Ind and SW CMa

Qunfeng Jiang

Thornton et al. (2026) reported 27 non-transiting circumbinary-planet candidates from excess apsidal motion in TESS eclipsing-binary timings. The classical stellar contribution is sensitive to target-specific radii, apsidal constants $k_2$, and rotation. We re-evaluate two evolved, double-lined eclipsing binaries in that sample: the pulsating system CH Ind and the Am system SW CMa. Their component masses and radii have been measured in dedicated binary studies, allowing the stellar contribution to be calculated directly. For CH Ind, six independent TESS sector nodes give $\dot{\omega}_{\rm obs}=1.82^{+0.99}_{-0.94}\times10^{-3}\ {\rm deg\,cycle^{-1}}$, while a coeval fit to the measured binary components predicts $\dot{\omega}_{\rm stars}=2.05^{+0.43}_{-0.34}\times10^{-3}\ {\rm deg\,cycle^{-1}}$. For SW CMa, its measured dimensions raise the classical term by a factor of about 16; the published target-specific prediction, $0.670\pm0.020\times10^{-3}\ {\rm deg\,cycle^{-1}}$, agrees with the observed $0.690\pm0.050\times10^{-3}\ {\rm deg\,cycle^{-1}}$. Neither system shows a significant excess prograde component. The comparison shows that candidates from a bulk search require target-specific binary models before a third-body interpretation is assigned.
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Earth and Planetary Astrophysics

Assessing Planetary Stability and Long-Term Habitability in Nearby Stellar Binaries: 70 Oph, 36 Oph, $\gamma$ Leo

Alyssa R. Jankowski, Juliette Becker, Catherine A. Clark et al. (+8 more)

Binary stars are common and have the potential to host habitable planets, which may reside in more complex habitable zones as compared to planets orbiting single stars. In this work, we use numerical simulations to assess the possibility that bright, nearby stellar multiples 36 Oph, 70 Oph, and $\gamma$ Leo could host habitable planets. We find that for the 36 Oph A/B system and for the 70 Oph A/B system, the stars can support planets residing in permanently habitable zones with low ejection rates and moderate eccentricity oscillations. The habitable zones around the red giants in the $\gamma$ Leo system exhibit severe dynamical instability due to the high binary eccentricity, eliminating the habitable zones around both stars. In these two systems, we find that planets in the habitable zone with orbits coplanar to that of the binary become uninhabitable due to interactions with the binary only 1.5% - 1.8% of the time, while planets with orbits 45 degrees misaligned to the plane of the binary experience larger oscillations in orbital eccentricity and as a result become uninhabitable 4.8% - 5.4% of the time. Our results identify 36 Oph and 70 Oph as promising targets for future missions such as the Habitable Worlds Observatory and SHERA, while suggesting that the stars in $\gamma$ Leo are unlikely to host any habitable planets. Our methods can be applied more generally to other binary stellar systems to refine target lists for upcoming habitable planet searches.
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All authors Alyssa R. Jankowski, Juliette Becker, Catherine A. Clark, Eric E. Mamajek, Jessie L. Christiansen, Yiting Li, Eduardo Bendek, Daniella Gagliuffi, Mark R. Giovinazzi, Simone Lilavois, Ryan Purviance

Earth and Planetary Astrophysics

A Radon Transform Perspective on Exoplanet Transits

Shotaro Tada

Transit light curves are usually analyzed under the assumption that the transiting planet has a circular sky-projected silhouette. However, planetary rotation, tides, rings, or atmospheric inhomogeneities can produce non-circular silhouettes. This raises the question of what information transit light curves can provide about the underlying two-dimensional attenuation map. In this paper, we show that, in a simple and transparent limit, the time derivative of the transit light curve during ingress or egress can be interpreted as a Radon-transform measurement of the planetary attenuation map, with the projection direction set by the local normal to the stellar limb. This viewpoint makes the information content of a single transit clear. Ingress and egress provide at most two projection angles, so the data constrain the Fourier transform of the attenuation map only along at most two radial slices, leaving a large null space. Physical constraints on the attenuation values and shape priors can reduce the range of viable solutions, but non-uniqueness generally remains. We further examine how realistic effects modify this picture. In particular, small stellar-limb curvature introduces weak sensitivity to transverse Fourier-space structure around the ideal slices, a sensitivity that is absent in the strict Radon-transform limit. These results provide a framework for understanding what transit light curves can and cannot reveal about non-circular planetary silhouettes.
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Earth and Planetary Astrophysics

The atmospheric vertical structure of Uranus and Neptune from thermochemical models: the impact of model assumptions

Thomas Douçot, Ravit Helled, Daniel Kitzmann et al. (+2 more)

The composition and temperature-pressure profile of the atmospheres of Uranus and Neptune are not well-determined. As observational data are limited, we often rely on chemical equilibrium computations to infer atmospheric abundances and cloud formation. The inferred atmospheric structures, however, strongly depend on several fundamental assumptions such as the elemental abundances and ratios, the condensation properties of the assumed species, or a reference temperature for the adiabatic structure. In this study we investigate the effects of different metallicities (1 to 80 solar), element ratios (C/O and S/N, from 0.1 to 2 and 0.19 to 1.6) and 1 bar temperatures (66 to 86 K) on the vertical structure of ice giant atmospheres. In particular, we use the chemical equilibrium code FastChem to derive mixing ratios and cloud structures for CH$_4$, NH$_3$, H$_2$S, H$_2$O and NH$_4$SH. We find that the models are very sensitive to the assumed parameters, yielding drastically different possible atmospheric structures. For the cases considered here, we find that mixing ratios and cloud deck altitudes can vary by more than an order of magnitude. Additionally, thermal profiles can differ by several tens of kelvins due to composition and 1-bar temperature. We advise that future ground-based observations and a dedicated mission to Uranus and/or Neptune are required to better characterize the atmospheric structure and composition of ice giants.
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All authors Thomas Douçot, Ravit Helled, Daniel Kitzmann, Ricardo Hueso, Audrey Vorburger

Earth and Planetary Astrophysics

Revisiting gravitational instability in protostellar discs with improved radiative cooling models

Alison K. Young, Ken Rice, Richard Booth et al. (+1 more)

Young discs are expected to be significantly more massive than those observed at $>1$ Myr and it is at this earliest stage that planet formation likely begins. Such massive discs may be susceptible to the gravitational instability (GI), therefore we need to determine the disc and stellar properties for which the GI is active to understand its role in early disc evolution and planet formation. Prior work has been limited by model assumptions and inaccuracies due to the complex nature of the thermodynamics of protostellar discs so we now revisit this question using an improved method to approximate radiative cooling within hydrodynamics simulations. We have explored a wide parameter space, representative of young protostellar discs of 0.1 to 1 M$_{\odot}$ and include irradiation from the host star. The parameters for which discs form spirals and fragment were found to differ to those obtained from earlier simulations. The outer regions of discs with radii of 50 au may be susceptible to fragmentation, meaning that GI-driven planet formation is not restricted to only the most extended discs. The additional thermal support due to stellar irradiation increases the disc mass that remains stable against GI: discs may reach up to $\gtrsim 0.4$ M$_*$ without fragmenting, providing a considerable quantity of material for building planets. Large scale spiral arms only developed for $M_*\lesssim$ 0.3 M$_{\odot}$, except in the most compact discs. Furthermore, the long-lived spiral structures that form tend to be flocculent and compact, indicating that large-scale spiral arms should not be considered a typical outcome of GI.
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All authors Alison K. Young, Ken Rice, Richard Booth, Farzana Meru

Earth and Planetary Astrophysics

Chondrule formation in the outer disk from the primary three-dimensional chemical composition of CM chondrules

Poula Ey{\dh}bjørnsdóttir, Anders Johansen and Elishevah van Kooten

Chondrules and their associated fine-grained rims record key processes in the early protoplanetary disk, yet the links between chondrule chemistry, morphology, and matrix complementarity remain poorly constrained. We investigate the major, minor, and trace element compositions of 66 chondrules and FGRs from the relatively unaltered CM carbonaceous chondrites Asuka 12236, Paris, and Maribo, together with their 3D morphology, using LA-ICP-MS and X-ray tomography. CM chondrules record systematic metal loss and evaporation of Si-rich mesostasis, driving initially CI-like precursor compositions toward more Mg- and Si-rich bulk compositions along the CI ratio line and toward increasingly Si-poor forsteritic assemblages. GEMS-like materials in pristine CM matrices closely mirror chondrule compositions and likely represent complementary condensates derived from evaporated mesostasis. Dust accreted onto chondrules is predominantly CI-like but contains about 14 wt.% complementary condensate material represented by chondritic amorphous silicates, reconciling Mg/Si complementarity between chondrules and matrix with the preservation of primordial organics and presolar grains. Morphological observations show no significant sectioning bias, consistent with CM chondrules being dominated by agglomerates of ~100 um microspherules. Many display grape-bunch textures produced by welding of smaller chondrules with metal-rich or CI-like rims. This structure may explain the chondrule moderately volatile-element plateau at about 0.3xCI. We propose a "micro-chondrule-first" scenario in which localized heating events produced small molten droplets that subsequently accreted CI-like dust and ice, aggregated, and experienced limited aqueous alteration. These observations place new constraints on chondrule formation in the outer disk and highlight the importance of localized melting and aggregation processes.
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Earth and Planetary Astrophysics

Are Hot Jupiters Tidally Disrupted During Stellar Main Sequence?

Qingru Hu, Wei Zhu, Yang Huang et al. (+1 more)

Once hot Jupiters (HJs) reach their very close orbits, they are expected to experience orbital decay due to tidal interactions with their host star. However, the strength of tidal dissipation is highly uncertain, and it remains an open question whether HJs are tidally disrupted during the stellar main sequence. A previous study found that HJ hosts have a smaller Galactic total velocity dispersion than their field star counterparts, which they interpreted as evidence of tidal disruption. We revisit this study and find that, after using the more reliable vertical velocity dispersion ($\sigma_W$) as the age indicator and accounting for the heterogeneity and anisotropy of their HJ sample, the kinematic age difference between their HJ hosts and matched field stars is significantly reduced. As an independent check, we collect HJs newly discovered by TESS and find that their $\sigma_W$ is statistically similar to that of matched field stars. We also find no statistically significant $\sigma_W$ difference between the field stars and the theoretically vulnerable ultra-hot Jupiters with $P<2$ d. Our results suggest that, after accounting for systematics in the age–velocity dispersion relation, there is no statistically strong evidence from the stellar kinematics that a large fraction of hot Jupiters around Sun-like stars are tidally destroyed during the stellar main sequence.
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All authors Qingru Hu, Wei Zhu, Yang Huang, Bowen Zhang

Earth and Planetary Astrophysics

Are Near Resonant Multiple-planet Systems from Kepler Young?

Wei Zhu and Qingru Hu

Recent studies have claimed that Kepler multi-planet systems hosting near-resonant planet pairs—particularly those near second-order mean-motion resonances (MMRs)—exhibit smaller stellar velocity dispersions than the general population of Kepler planet hosts. Interpreting velocity dispersion as an age indicator, these works concluded that near-resonant systems are systematically younger. We revisit this claim, but we explicitly account for contamination by thick disk stars, which are kinematically hotter and follow a different age-velocity dispersion relation (AVR) than thin disk stars. Using the kinematic criterion to separate thin and thick disk stars, we show that systems classified as having plausible second-order resonant pairs are preferentially hosted by brighter, closer stars and are therefore less contaminated by thick disk stars than the overall sample. After applying a cut to remove probable thick disk contaminants (${\rm TD/D}<0.1$), the vertical velocity dispersion of near-resonant systems becomes statistically indistinguishable from that of the overall Kepler multi-planet sample. We conclude that the apparent kinematic youth of near-resonant systems in Kepler may not be due to a genuine age difference, but rather arises from observational selection effects linked to host star properties and planet detectability. We also comment on the kinematic ages of ultra-short-period planets (USPs).
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Wednesday 12 August

Earth and Planetary Astrophysics

Climates of Gl 514 b

Héctor E. Delgado Díaz, Rory Barnes, Russell Deitrick et al. (+2 more)

The continuous discovery of exoplanets, each with distinctive stellar and planetary properties, along with the development of higher resolution ground and space telescopes has positioned climate evolution as a fundamental component of the study of habitability. In particular, the planet Gl 514 b, located within the habitable zone of an M0.5 dwarf star 7.62 pc from Earth, is a candidate for direct observations with future ground and space-based telescopes and therefore worthy of climate modeling. One notable aspect of this planet is its eccentricity of $e = 0.45^{+0.15}_{-0.14}$, which could affect the seasonal climate by inducing large swings in instellation over the course of an orbit. Hence, we simulate a plausible range of climates on this planet to assess the likelihood that its surface is habitable as well as estimate the surface ice coverage, which could affect the photometric signal. To perform these simulations, we use an energy balance model to explore the parameter space permitted by the observations and the allowed ranges of the obliquity, eccentricity, atmospheric CO$_2$, precession angle, land fraction, and land distribution. We find the planet is most likely to be in either a snowball or ice free state, but about 1.27% of our simulations contain polar ice caps or an ice belt. A partial pressure of CO$_2$ in the range of 7.25-9.5 bar permits the planet's surface to be habitable. These results constrain the orbital, rotational, and physical conditions required for surface habitability of Gl 514 b and will help guide future direct-imaging surveys of this and similar planets.
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All authors Héctor E. Delgado Díaz, Rory Barnes, Russell Deitrick, Mario Damasso, Nathaniel Brown

Earth and Planetary Astrophysics

Evolutionary tracks of giant planets formed by disk instability

Mirco Bussmann and Ravit Helled

The evolution of giant planets depends on their formation history. While several evolutionary models self-consistently link planet formation by core accretion to long-term evolution, such models for planets formed by disk instability are lacking. We simulate the evolution of giant planets formed by disk instability and follow their evolution including the pre-collapse phase, dynamical collapse, and long-term contraction in a unified numerical framework. The evolution is simulated using the MESPA code with modifications that allow us to model gas clumps in the pre-collapse phase. We consider masses between 1 and 12 Jupiter masses and metallicities ranging from 0.5 to 2 times the protosolar value. We confirm that the pre-collapse timescale strongly depends on the planetary mass, and that after dynamical collapse the objects reach a state of long-term contraction which lasts for billions of years. We show that metallicity is a major source of uncertainty in mass estimates derived from the age-luminosity relations. For the metallicity range considered here, we find that for a given measurement of age and luminosity the difference in the inferred mass can be up to 1.5 Jupiter masses. We find that our evolution tracks predict masses that are consistent with the measured dynamical mass constraints for HR 8799 e, AF Lep b, Beta Pic b and Beta Pic c. We also show that both core accretion and disk instability can lead to very similar long-term evolutionary tracks. The agreement between our models and dynamical mass measurements suggests that disk instability remains a viable formation pathway for giant exoplanets. The luminosity evolution alone cannot distinguish between the two formation pathways. Finally, we suggest that planetary metallicity must be taken into account when inferring the masses of young giant planets from their luminosities, as it significantly affects their evolution.
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Earth and Planetary Astrophysics

Three new exoplanet systems from the Dispersed Matter Planet Project

J.R. Barnes, C.A. Haswell, Z.O.B. Ross et al. (+7 more)

We present a radial velocity analysis of three bright, low-activity stars identified by the Dispersed Matter Planet Project (DMPP). We use a Bayesian framework to compare purely Keplerian models with models incorporating stellar activity via a quasi-periodic Gaussian Process (GP). DMPP-7 (HD 118006) is a slightly evolved star that harbours a single 0.72 Saturn-mass giant ($m_\textrm{p}\sin i$ = 69 M$_\oplus$) with an orbital period of P = 4.93 d. A longer 21 d - 22 d period cannot be conclusively confirmed as a stellar rotation signature rather than a purely Keplerian signal. For HD 67200, which exhibits Ca ii H&K variability, a model with only a GP is strongly favoured over a purely dynamical model. The GP model shows moderate evidence for a single Keplerian with P = 2.67 d. For HD 2134, a 21 d - 32 d rotation period signal is associated with tentative FWHM variability. A model with a GP is not conclusively favoured, but all models considered show moderate evidence for an additional single Keplerian with P = 2.78 d. Despite our target selection favouring near edge-on orbital geometries, we find no evidence for transits in TESS photometry. DMPP-7 b lies at the transition between the high-radius population and the Neptunian ridge and savannah regions. Further observations are required to establish whether the coherent short-period HD 67200 and HD 2134 signals are stellar or dynamical in origin. If planetary, the signals correspond to minimum masses of $m_\textrm{p}\sin i$ = 2.07 M$_\oplus$ and $m_\textrm{p}\sin i$ = 2.86 M$_\oplus$
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All authors J.R. Barnes, C.A. Haswell, Z.O.B. Ross, E. Rutherford, M.R. Standing, A.T. Stevenson, D. Staab, L. Fossati, J.S. Jenkins, D. Alves

Earth and Planetary Astrophysics

Chemical Tracers for 3D Atmospheric Asymmetries on WASP-69 b

Nidhi Bangera, Ludmila Carone, Vikas Soni et al. (+6 more)

Warm giant exoplanets exhibit strong three-dimensional temperature contrasts that can significantly alter atmospheric chemistry through quenching and photochemistry, yet transmission spectra are commonly interpreted using one-dimensional, limb-averaged models. Such simplifications may bias inferred atmospheric properties, particularly metallicity and C/O ratio. In this work we investigate the relative influence of atmospheric composition and three-dimensional thermal structure on atmospheric chemistry and transmission spectra using WASP-69b as a test case. WASP-69b is a ~900K warm Saturn, residing in a thermal regime especially sensitive to disequilibrium chemistry. We use three-dimensional general circulation model derived pressure-temperature profiles as inputs for a one-dimensional photochemical-kinetics model to resolve longitudinal and latitudinal chemical asymmetries across the atmosphere. We find that CH4 exhibits strong latitudinal variations linked to deep quench temperatures, while SO2 shows longitudinal asymmetries driven by upper-atmospheric photochemistry and irradiation geometry. In contrast, CO2 remains comparatively insensitive to spatial thermal variations and emerges as a robust tracer of atmospheric metallicity. Synthethic transmission spectra reveal that three-dimensional chemical asymmetries can produce spectral variations comparable to those induced by metallicity itself, demonstrating that limb-averaged interpretations can mask substantial spatial structure in warm giant exoplanet atmospheres.
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All authors Nidhi Bangera, Ludmila Carone, Vikas Soni, Kenneth Goodis Gordon, Luca Fossati, Helena Lecoq-Molinos, Paul B. Rimmer, Peter Woitke, Christiane Helling

Earth and Planetary Astrophysics

Infrared-to-visible albedo ratio of Phobos: Comparison with primitive asteroids

T.J. Dyer, J. Beccarelli, M. Delbo et al. (+5 more)

Aims. The ratio between infrared and visible albedo, pIR/pV, provides a simple proxy for the spectral slope of asteroid surfaces between the visible and near-infrared wavelength ranges. The aim of this work is to assess whether the different spectral units of Phobos occupy the same spectral parameter space as the primitive asteroid populations in order to confirm or not its possible asteroidal origin. Methods. For each of the three spectral units of Phobos (Red, Transitional and Blue), we extracted averaged, normalised reflectance spectra by comparing normalised reflectance in the visible (0.50-0.60 $\mu$m) and near-infrared (3.1-3.8 $\mu$m) wavelength ranges from the Mars Express OMEGA instrument, to compute a proxy for the infrared-visible albedo ratio ($R_P$). Then, using the database of visible and infrared albedos compiled in the Minor Planet Physical Properties Catalogue (MP3C), we computed asteroid pIR/pV values ($R_A$), to compare to those for Phobos. Results. The $R_P$ for the Red, Transitional and Blue regions vary between 2.90 and 3.12, 2.32 and 2.35, 1.64 and 1.85 respectively. These values span a range occupied by primitive asteroid populations, with the Transitional and Red regions coinciding with the high ratio regime within the pIR/pV domain, which is commonly associated with red-sloped primitive asteroids, including D- and T-type objects as well as Jupiter Trojans.
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All authors T.J. Dyer, J. Beccarelli, M. Delbo, C. Avdellidou, M. Pajola, A. Milton, A. Lucchetti, G. Munaretto

Earth and Planetary Astrophysics

Altered Cosmic Organics as Venus' Ultraviolet Absorbers

Rakesh Mogul, Mikhail Yu. Zolotov, Michael J. Way et al. (+1 more)

Venus' ultraviolet (UV) absorbers significantly contribute to the atmosphere's energy budget. However, the composition of these absorbers remains a mystery. Here, we show that mixtures of polycyclic aromatic hydrocarbons (PAHs) and iron-bearing compounds, analogs of altered cometary dust, excellently match Venus' spectra from the cloud tops to the sub-cloud atmosphere across the UV and visible wavelengths. The molecular compositions for the cloud tops (5-10 ring PAHs and ferric chloride), decomposed cloud aerosols (3-4 ring PAHs and acid ferric sulfate), and sub-cloud atmosphere (5-10 PAHs and ferric hydroxy sulfates) are consistent with the stepwise alteration of cosmic dust. These steps include sourcing of the PAHs and iron from thermally unablated and ablated dust particles, respectively, reactions with sulfuric acid in the clouds, and thermal decomposition below the clouds. Geologically short timelines of cosmic influx (minimum of 600 and 3 kyr) would respectively yield the cloud top carbon and iron concentrations. Hence, we propose a unified origin for Venus' absorbers, which may arise from cometary dust via altitude-dependent alteration pathways from the mesosphere to the surface, with PAHs serving as the primary UV absorbers and iron compounds as the dominant absorbers by mass.
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All authors Rakesh Mogul, Mikhail Yu. Zolotov, Michael J. Way, Sanjay S. Limaye

Earth and Planetary Astrophysics

Dynamic Trajectory Analysis of Meteoroids Showing Minimal Deceleration

Thomas Stevenson, Ellie Sansom, Hadrien Devillepoix et al. (+8 more)

Meteoroids decelerate and ablate as they descend through the atmosphere, however a portion of instrumentally observed meteors show little measurable deceleration and remain poorly characterised. These are referred to as minimally decelerating objects (MDOs). The traditional alpha-beta method of dynamic trajectory analysis cannot reliably determine their preatmospheric masses or rates of ablation. We present a new approach for estimating the ballistic coefficients (alpha) and mass loss parameters (beta) of MDOs, allowing their inclusion in dynamic analyses. This new method employs bulk ablation coefficients derived from instrumentally observed meteorite falls and large meteor shower bodies. It is applied to MDOs comprising approximately one-third of the Global Fireball Observatory (GFO) 2014 - 2024 dataset. Our results show that MDOs are predominantly small objects occupying a distinct region of alpha-beta space. Material types can be identified using supplementary data such as emission spectra, which we demonstrate using observations of 10 small iron meteoroids. This methodology expands the range of meteoroid populations accessible to dynamic trajectory analysis, providing new constraints on meteorite deposition and the compositional diversity of near-Earth objects.
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All authors Thomas Stevenson, Ellie Sansom, Hadrien Devillepoix, Maria Gritsevich, Anna Zappatini, Peter Jenniskens, Christopher Herd, Jonti Horner, Nick Moskovitz, Samantha Hemmelgarn, Luke Daly

Tuesday 11 August

Earth and Planetary Astrophysics · Cross-listed from astro-ph.SR

Diameters and Temperatures VII: High-angular resolution measurements of Solar-type stars with the CHARA Array

Tabetha S. Boyajian, Ashley A. Elliott, Emelly D. Tiburcio et al. (+8 more)

We present interferometric measurements of angular diameters for 27 nearby solar-type stars obtained with the Precision Astronomical Visible Observations (PAVO) beam combiner at the CHARA Array. The sample spans a broad range of metallicities, includes several known exoplanet hosts, and covers evolutionary stages from the zero-age main sequence to mildly evolved subgiants. Uniform-disk and limb-darkened angular diameters were measured for each target and combined with bolometric fluxes and Gaia parallaxes to determine precise, model-independent stellar radii, effective temperatures, and luminosities. We achieve typical uncertainties of $\sim1$% in radius and $\sim1.5$% in effective temperature. Comparisons with multiple stellar evolutionary model grids yield mass and age estimates and enable assessment of grid-to-grid systematics, highlighting sensitivities to abundances, evolutionary stage, and proximity to grid boundaries. Our results provide empirical benchmarks for testing stellar evolutionary theory, refining surface brightness-color relations, and improving the characterization of exoplanet host stars.
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All authors Tabetha S. Boyajian, Ashley A. Elliott, Emelly D. Tiburcio, Kaspar von Braun, Gail Schaefer, Timothy R. White, Daniel Huber, Michael Ireland, Jeremy Jones, Tyler Ellis, Eliot Hiegel

Earth and Planetary Astrophysics

Spectral Energy Distribution Analysis for Habitable Worlds Observatory Target Stars

Stephen R. Kane, Kaspar von Braun, Tara Fetherolf et al. (+1 more)

The Habitable Worlds Observatory (HWO) will directly image and characterize planets potentially similar to Earth orbiting nearby stars. Accurate stellar properties, particularly effective temperatures ($T_\mathrm{eff}$), angular diameters ($\theta_\star$), and bolometric fluxes ($F_\mathrm{bol}$), are essential for reliable Habitable Zone (HZ) calculations, exoplanet yield predictions, and coronagraph design trade studies. We present a spectral energy distribution (SED) analysis for the 164 stars from the HWO Exoplanet Exploration Program (ExEP) list, using $\chi^2$-minimization fits of empirical spectral templates from the Pickles stellar spectral flux library to broadband photometric data. The SED fits provide direct measurements of $F_\mathrm{bol}$. We adopt spectroscopic $T_\mathrm{eff}$ values from the PASTEL catalog for 127 of the 164 stars, with the remainder drawn from the HWO ExEP catalog, and use these in combination with $F_\mathrm{bol}$ to calculate $\theta_\star$ via the Stefan-Boltzmann equation. As a consistency check, we compare the Pickles template $T_\mathrm{eff}$ with the adopted spectroscopic values and find agreement to within $\sim$3% for 65% of the sample, with a systematic tendency for the templates to yield cooler values. We identify 48 stars with discrepancies exceeding 200~K, including close binary systems where photometric contamination compromises the SED solution. We discuss the implications for HZ boundary calculations, atmospheric retrieval of directly imaged planets, and target prioritization for HWO. This SED catalog constitutes a uniform set of empirically determined $F_\mathrm{bol}$ values and associated stellar parameters for the HWO target sample.
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All authors Stephen R. Kane, Kaspar von Braun, Tara Fetherolf, Natalie R. Hinkel

Earth and Planetary Astrophysics

A Pair of Warm Saturn-mass Planets near the 2:1 Mean Motion Resonance around TOI-3850

Sean Collins, Michelle Kunimoto, Nicolas B. Cowan et al. (+24 more)

Warm Jupiters, with orbital periods of $10$–$200~\rm{days}$ and radii exceeding $8~R_{\oplus}$, are a relatively understudied class of exoplanets occupying the parameter space between hot Jupiters and more widely separated, colder Jupiter analogs. In this work, we report the detection of a multi-planet warm Jupiter system around TOI-3850 (TIC-143008050), a moderately active, near-solar metallicity G0 dwarf star observed by TESS in Sectors 15, 21, 41, 48 and 75. Initially, a single candidate planet was discovered by TESS, displaying transit timing variations (TTVs) with an amplitude of $\sim 1~\rm hr$ and a super-period of $513~\rm days$. Through a combination of transit photometry, radial velocity observations with MAROON-X, and TTV modeling, we identify two planets: TOI-3850 b $(P_b=14.484\pm0.002~\mathrm{days},~ M_b =112\pm20~M_{\oplus},~e_b = 0.018\pm0.008, R_b = 12.07\pm0.09~R_{\oplus}, ~T_{\rm{eq}}=841\pm10~\rm{K})$, a transiting warm Jupiter, and TOI-3850 c $(P_c=29.85\pm0.01~\mathrm{days},~ M_c =90\pm15~M_{\oplus},~e_c < 0.015, ~T_{\rm{eq}}=661\pm7~\rm{K})$, a non-transiting, Saturn-mass companion. The two planets lie wide of the 2:1 mean motion resonance $(P_c/P_b \approx 2.06)$, consistent with a formation history involving disk-driven migration. $N$-body integrations indicate that TOI-3850 c may begin to transit on decadal timescales, while TOI-3850 b remains a promising target for follow-up atmospheric characterization.
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All authors Sean Collins, Michelle Kunimoto, Nicolas B. Cowan, Keivan G. Stassun, Jack J. Lissauer, Ze'ev Vladimir, Teo Močnik, Ernesto Elenter, David W. Latham, Karen A. Collins, Jacob Bean, Stephanie Striegel, Khalid Barkaoui, Ritvik Basant, Tanya Das, Raquel Forés-Toribio, Akihiko Fukui, Jose A. Muñoz, Felipe Murgas, Enric Palle, Ivan A. Strakhov, Richard P. Schwarz, Avi Shporer, Gregor Srdoc, Chris Stockdale, Neil B. Thomas, Francis P. Wilkin

Earth and Planetary Astrophysics

Formation of multiple dust rings and gaps in protoplanetary discs by a single migrating planet. A parameter study in locally isothermal discs

Sören C. Meiners, Kim M. Weiskopf, Thomas Rometsch et al. (+1 more)

ALMA observations show that large protoplanetary discs usually contain multiple concentric dust rings separated by dark gaps. A natural explanation is dust-trapping at the edges of gaps opened by newly formed planets. However, planets typically migrate inward on timescales shorter than disc lifetimes, seemingly at odds with rings at large radii. We aim to investigate the conditions under which migrating planets can form long-lived, multi-ringed structures out to $r\sim 150$ au to constrain the parameter space for the planetary origin hypothesis of rings. Using the FargoCPT hydrodynamics code, we ran two-dimensional, locally isothermal disc models with a single migrating planet, varying disc aspect ratio, viscosity ($\alpha$), and planetary mass. In all models, the planet eventually stalls in a deep gap. At $\alpha\leq 10^{-4}$, secondary spirals launched by the planet can open additional gaps at smaller radii. When planets exceed twice the local thermal mass before stalling, they enter a regime of alternating slow and type-III rapid migration, leaving partial gaps outside their orbit. The gap edges consistently feature pressure maxima that trap dust. These begin as large vortices at $\alpha\leq 10^{-4}$, but gradually smear out into rings before dissipating. The type-III remnant rings dissipate quickly at $\alpha=10^{-3}$, but persist for at least 300-500 kyr at $\alpha\leq 10^{-4}$. Both smear-out and dissipation timescales increase with lower $\alpha$. Our results show that migrating planets can reproduce observed multi-ringed structures in discs with $\alpha\lesssim 10^{-4}$ through their stall ($r\lesssim 50$ au), secondary gap-opening ($r\lesssim 20$ au), and type-III migration remnants (extending to $r\sim 150$ au for Jupiter-mass planets in sufficiently massive discs). Longer simulations will be required to compare the statistics of ring-to-vortex occurrence to observations.
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All authors Sören C. Meiners, Kim M. Weiskopf, Thomas Rometsch, Cornelis P. Dullemond

Earth and Planetary Astrophysics · Cross-listed from astro-ph.IM

Early Exploration of the Scientific Discovery Space for the Habitable Worlds Observatory

Courtney D. Dressing, Danica Adams, Evelyne Alecian et al. (+324 more)

The Habitable Worlds Observatory (HWO) is a future NASA flagship mission concept identified by the Astro2020 Decadal Survey as the highest priority for large space missions. HWO should conduct "transformative astrophysics" and search for biosignatures in the atmospheres of approximately 25 potentially Earth-like planets. To further the early-stage development of HWO, NASA formed the Science, Technology, Architecture Review Team (START). In turn, START invited the scientific community to join working groups to explore the potential discovery space. In this paper, we present 70 science cases that resulted from this process. The cases address four scientific pillars: growth of galaxies (15 cases), evolution of the elements (13 cases), solar systems in context (32 cases), and living worlds (10 cases). Combined, they would address 27 of the 30 science questions and discovery areas identified by Astro2020. The 140 observing programs needed for the 70 investigations encompass a rich variety of spectroscopic (for 87% of science cases) and photometric (for 30%) observations extending from the UV to the NIR. Additionally, high-contrast and polarimetric capabilities would be needed for 34% and 27% of science cases, respectively. Access to UV wavelengths is critical: 83% of science cases need data at wavelengths <400 nm, and 26% extend to <100 nm. In the NIR, 26% of science cases need observations at wavelengths >=2000 nm. Pursuing the full portfolio of science would also necessitate precise astrometry for planet mass measurement, rapid response capabilities, a large instantaneous field of regard, non-sidereal tracking, saturation mitigation strategies, and high dynamic range.
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All authors Courtney D. Dressing, Danica Adams, Evelyne Alecian, Gagandeep Anand, Giada Arney, Sarah Gomes Aroucha Barbosa, Martin Barstow, Joanna K. Barstow, Rachael L. Beaton, Eduardo Bendek, Svetlana Berdyugina, Julie Biedermann, Sarah Blunt, Sanchayeeta Borthakur, Kara Brugman, Joseph N. Burchett, Eric Burns, Jenna M. Cann, Ludmila Carone, Cody A. Carr, Richard Cartwright, Renyue Cen, Jean-yves Chaufray, Pin Chen, Lígia F Coelho, Kyle Cook, Nicolas B. Cowan, Patricio E. Cubillos, Alexandre David-Uraz, Tansu Daylan, Jessica E. Doppel, Leonardo dos Santos, Meredith Durbin, Rana Ezzeddine, Tara Fetherolf, Theresa Fisher, Leigh N. Fletcher, Luca Fossati, Ana I Gómez de Castro, Kaz Gary, Varoujan Gorjian, Yasuhiro Hasegawa, Qiuhan He, Natalie Hinkel, Keri Hoadley, Renyu Hu, Noam Izenberg, Estelle Janin, Mathilde Jauzac, Stephen R. Kane, Theodora Karalidi, Émilie Anne Lafléche, David J. Lagattuta, Érika Le Bourdais, Mary Anne Limbach, Jacob Lustig-Yaeger, Eric Mamajek, Kathleen Mandt, Frédéric Marin, Taro Matsuo, Stephan R. McCandliss, Michael W. McElwain, Emma Miles, Michiel Min, Leonidas A. Moustakas, Coralie Neiner, Elisabeth Newton, James W Nightingale, Stephanie Olson, Colby Ostberg, Apurva V. Oza, Fabio Pacucci, Roberta Paladini, Niki Parenteau, Lynnae C. Quick, Ramses Ramirez, Sukrit Ranjan, Isabel Rebollido, Bin B. Ren, Kurt D Retherford, Jason Rhodes, Ian U. Roederer, Sabina Sagynbayeva, Edward Schwieterman, Adam Smercina, Krista Lynne Smith, Antoine Strugarek, Megan Taylor Tillman, Vivian U, Georgios N. Vassilakis, Hannah R. Wakeford, Sara Walker, Siyi Xu, Lulu Zhang, Alejandra Aguirre-Santaella, Munazza K. Alam, Amirnezam Amiri, Ramya M Anche, Sarah E. Anderson, David R. Ardila, Karla Z. Arellano-Córdova, Natasha E. Batalha, Thomas G.Beatty, Juliette Becker, Enrica Bellocchi, Mark Booth, Médéric Boquien, Sarah E. I. Bosman, Jean-Claude Bouret, Vincent Bourrier, Matteo Brogi, Andrew M. Buchan, Blakesley Burkhart, Jennifer A. Burt, José A. Caballero, Sarah L Casewell, Frances H. Cashman, Laura Chin, Yumi Choi, Jessie Christiansen, Francesca Civano, Kyle W. Cook, Brandon Park Coy, Brendan P Crill, Leroy Cronin, Håkon Dahle, Mario Damiano, William Danchi, Satyapriya Das, Brice-Olivier Demory, Jamie Dietrich, Steven Dillmann, Chuanfei Dong, Dwaipayan Dubey, Patrick Dufour, Arika Egan, Christiana Erba, Steve Ertel, Raissa Estrela, Vincent Van Eylen, Virginie Faramaz-Gorka, Andrzej Fludra, Sophia Flury, Andrew Fox, Kevin France, David M. French, Marina Galand, Tianmu Gao, Antonio García Muñoz, Miriam Garcia, Kenneth Gayley, Megan Gialluca, Samantha Gilbert-Janizek, Leonardos Gkouvelis, Kenneth E. Goodis Gordon, Clémence Gourvès, Jonathan Grone, Jacob Haqq-Misra, Caleb K. Harada, Zachary Hartman, Samantha Hasler, Calum Hawcroft, Matthew J. Hayes, Amanda R. Hendrix, Brandon Hensley, Svea Hernandez, Erin K. S. Hicks, Benne W. Holwerda, Carly Howett, Ziyu Huang, Richard Ignace, Caitriona M Jackman, Chafi Jamal, Shingo Kameda, Tiffany Kataria, Gagandeep Kaur, Finnegan Keller, Habib Khosroshahi, Alina Kiessling, Kristina Kislyakova, Oleg Kochukhov, Anton M. Koekemoer, Brad Koplitz, Joshua Krissansen-Totton, Jiri Krticka, Alvaro Labiano, Pierre-Olivier Lagage, Steph LaMassa, Erini Lambrides, Alexandra Le Reste, Nan Liu, Joe Llama, Emma Louden, Nataliea Lowson, Isabel Márquez, Evelyn J. R. Macdonald, Meredith MacGregor, Sangeeta Malhotra, Richard Massey, Erin May, L. C. Mayorga, Michael McElwain, Sean McGee, Alexia McKenzie, Athina Meli, Bertrand Mennesson, Connor Metz, Drew M. Miles, Aquib Moin, Mark Moussa, Themiya Nanayakkara, Dibyendu Nandy, Yaël Nazé, Marc Neveu, Eric Nielsen, John Noonan, Jessica L. Noviello, John M. O'Meara, Antonija Oklopčić, Chris Packham, Enric Palle, Emaad Paracha, Lucas Patty, Vasiliki Pavlidou, Sarah Peacock, Chris Pearson, Marc Postman, Andreas Quirrenbach, Swara Ravindranath, Seth Redfield, Joe P. Renaud, Malena Rice, Jane R. Rigby, Giulia Roccetti, Keighley E. Rockcliffe, Donna Rodgers-Lee, Jael Rojas Miguel, Maissa Salama, Samir Salim, Evan Scannapieco, Claudia Scarlata, Martin Schlecker, Steve Schulze, Paul Scowen, Darryl Zachary Seligman, Zacory Shakespear, Evgenya Shkolnik, Nick Siegler, Breann Sitarski, Louie Slocombe, Gopika SM, Russell J. Smith, Jennifer Sobeck, Daphne Stam, Kendall Sullivan, Takahiro Sumi, Yudai Suzuki, Christy Till, Armen Tokadjian, Vasuda Trehan, Grant Tremblay, Noah Tuchow, Margaret Turcotte Seavey, Jake D. Turner, Sarah Tuttle, Asif ud-Doula, Anna Grace Ulses, Connor Vancil, Aline Vidotto, Geronimo Villanueva, Jessica M Weber, Dale Weigt, Maximilian von Wietersheim-Kramsta, Thomas G. Wilson, David J. Wilson, Nicholas F. Wogan, Maria Womack, Michael L. Wong, John F Wu, Mark Wyatt, John Ziemer, Tiziano Zingales, Ryan Begley, Enrico Biancalani, Dmitry Blinov, Alexandre Branco, Esra Bulbul, Guillaume Chaverot, Catherine A. Clark, Jaime S. Crouse, Filippo D'Ammando, Achrene Dyrek, Oscar A. Flores Gaitán, Searra Foote, Cecilia Garraffo, Christopher Garry, Nikolaos Georgakarakos, Arvind F. Gupta, Daniel Huber, Brianna Isola, Nikhita Kalluri, Aafaque Khan, Amir H. Khoram, Adam B. Langeveld, Lucie Leboulleux, Briley Lewis, Anna Lewkowicz, Laurent Mahy, Liton Majumdar, Luigi Mancini, Joice Mathew, Dimitri Mawet, David Mouillet, Shantanusinh Parmar, Junellie Perez, Lorenzo Pino, Alex Polanski, Francisco J. Pozuelos, Tyler Richey-Yowell, Cleber Silva, Ramdayal Singh, Arif Solmaz, Angelle Tanner, Konstantinos Tassis, Luca Tonietti, Laura D. Vega, Aiden S. Zelakiewicz

2608.11294 · 11 Aug · 215 pages, 18 figures, 16 tables. This to-be-submitted manuscript summarizes and synthesizes science cases developed by the Habitable Worlds Observatory START and science working groups. See Table 1 for a roadmap, Table 5 for a list of science cases, Figure 11 for a visualization of common observational needs, Figure 16 for connections to Astro2020, and Tables 6-15 (after conclusions) for details

Abstract PDF $PLNT ×2$EVO ×1$GLXY ×1