arXiv subjects

Jacob Bean

Publications and source records attributed to Jacob Bean.

At least 19 recordsLinked to original sources

arXiv2026

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

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.

astro-ph.EP↗

arXiv2026

RV and TTV Measurements of Two Transiting Long-Period Giants around TOI-4600

TOI-4600b and c, originally identified by the Transiting Exoplanet Survey Satellite (TESS) and reported by I. Mireles et al. (2023), are a rare pair of transiting long-period giant planets ($\rm P_b=82.7$ days, $\rm P_c=482.8$ days) orbiting an early K dwarf. In this work, we refine the orbital parameters of the TOI-4600 system by combining new TESS photometry, ground-based transit follow-up, and radial velocity (RV) observations from MAROON-X. We obtain improved constraints on planetary masses and eccentricities, and update other parameters, such as the stellar age. For TOI-4600b, we measure a mass of $M_p = 74.7^{+4.7}_{-4.4}\,M_{\oplus}$ and an eccentricity of $e=0.153^{+0.020}_{-0.018}$, and $M_p = 212.53^{+13.26}_{-13.03}\,M_{\oplus}$ and $e=0.219^{+0.015}_{-0.018}$ for TOI-4600c. We find significant transit timing variations (TTV) in both planets, with semi-amplitudes of approximately $1$\,hr. We derive Transit Spectroscopy Metric values of 16.87 for TOI-4600b and 10.09 for TOI-4600c, indicating that both planets are promising JWST targets for studying the atmospheres of temperate and cold Jupiters, a relatively poorly characterized sample thus far. These updated parameters and TTV ephemerides are important for planning and interpreting future photometric, spectroscopic, and dynamical studies of the TOI-4600 system.

astro-ph.EP↗

arXiv2025

A Stellar Magnesium to Silicon ratio in the atmosphere of an exoplanet

The elemental compositions of exoplanets encode information about their formation environments and internal structures. While volatile ratios such as carbon-to-oxygen (C/O) are used to trace formation location, the rock-forming elements - magnesium (Mg), silicon (Si), and iron (Fe) - govern interior mineralogy and are commonly assumed to reflect the host star's abundances. Yet this assumption remains largely untested. Ultra-hot Jupiters, gas-giant exoplanets with dayside temperatures above 3000 K, provide rare access to refractory elements that remain gaseous. Here we present high-resolution thermal emission spectroscopy of the exoplanet WASP-189b (Teq = 3354^{+27}_{-34} K) obtained with the Immersion Grating Infrared Spectrometer (IGRINS) on Gemini South. We detect neutral iron (Fe I), magnesium (Mg I), silicon (Si I), water (H_2O), carbon monoxide (CO), and hydroxyl (OH) at signal-to-noise ratios exceeding 4, and retrieve their elemental abundances. We show that the Mg/Si, Fe/Mg, and Si/Fe ratios are consistent with stellar values, while the refractory-to-volatile ratio is enhanced by roughly a factor of ~2. These findings demonstrate that giant-planet atmospheres can preserve stellar-like rock-forming ratios, providing an empirical validation of the stellar-proxy assumption that underpins planetary composition and formation models across exoplanet systems.

astro-ph.EP↗

arXiv2025

An Earth-like Density for the Temperate Earth-sized Planet GJ 12b

While JWST has provided us with the opportunity to probe the atmospheres of potentially-habitable planets, observations of the TRAPPIST-1 system have shown us that active stars severely complicate efforts at studying their planets. GJ 12b is a newly-discovered temperate (Teq ~ 300 K), Earth-sized (Rp = 0.96 +/- 0.05 Earth radii) planet orbiting an inactive M dwarf that might be a good alternate to the TRAPPIST-1 planets for atmospheric characterization. In this paper, we use MAROON-X radial velocities to measure a mass of 0.71 +/- 0.12 Earth masses for GJ 12b. We also find moderate evidence that the planet has an eccentric (e ~ 0.16) orbit. GJ 12b's mass results in a planetary density comparable to or less dense than Earth, possibly indicating the presence of water or a low bulk iron mass fraction. With its low mass, GJ 12b is likely within reach of JWST transmission spectroscopy observations, making it an excellent target for determining the location of the cosmic shoreline. Its low mass may mean that the planet could have trouble retaining its primary atmosphere during the star's active pre-main-sequence phase. However, if it has a heightened eccentricity, it may be able to sustain a secondary atmosphere through tidally-induced volcanism.

astro-ph.EP↗

arXiv2024

Searching for GEMS: Characterizing Six Giant Planets around Cool Dwarfs

Transiting giant exoplanets around M-dwarf stars (GEMS) are rare, owing to the low-mass host stars. However, the all-sky coverage of TESS has enabled the detection of an increasingly large number of them to enable statistical surveys like the \textit{Searching for GEMS} survey. As part of this endeavour, we describe the observations of six transiting giant planets, which includes precise mass measurements for two GEMS (K2-419Ab, TOI-6034b) and statistical validation for four systems, which includes validation and mass upper limits for three of them (TOI-5218b, TOI-5616b, TOI-5634Ab), while the fourth one -- TOI-5414b is classified as a `likely planet'. Our observations include radial velocities from the Habitable-zone Planet Finder on the Hobby-Eberly Telescope, and MAROON-X on Gemini-North, along with photometry and high-contrast imaging from multiple ground-based facilities. In addition to TESS photometry, K2-419Ab was also observed and statistically validated as part of the K2 mission in Campaigns 5 and 18, which provides precise orbital and planetary constraints despite the faint host star and long orbital period of $\sim 20.4$ days. With an equilibrium temperature of only 380 K, K2-419Ab is one of the coolest known well-characterized transiting planets. TOI-6034 has a late F-type companion about 40\arcsec~away, making it the first GEMS host star to have an earlier main-sequence binary companion. These confirmations add to the existing small sample of confirmed transiting GEMS.

astro-ph.EP↗

arXiv2024

Stellar Characterization and Chemical Abundances of Exoplanet Hosting M dwarfs from APOGEE Spectra: Future JWST Targets

Exoplanets hosting M dwarfs are the best targets to characterize Earth-like or super-Earth planetary atmospheres with the James Webb Space Telescope (JWST). We determine detailed stellar parameters ($T_{\rm eff}$, log$g$, and $\xi$) and individual abundances of twelve elements for four cool M dwarfs hosting exoplanets TOI-1685, GJ 436, GJ 3470, and TOI-2445, scheduled for future observations by the JWST. The analysis utilizes high-resolution near-infrared spectra from the SDSS-IV APOGEE survey between 1.51-1.69$\mu$. Based on 1D-LTE plane-parallel models, we find that TOI-2445 is slightly metal-poor ([Fe/H] = -0.16$\pm$0.09), while TOI-1685, GJ 436 and GJ 3470 are more metal-rich ([Fe/H] = 0.06$\pm$0.18, 0.10$\pm$0.20 dex, 0.25$\pm$0.15). The derived C/O ratios for TOI-2445, TOI-1685, GJ 436, and GJ 3470 are 0.526$\pm$0.027, 0.558$\pm$0.097, 0.561$\pm$0.029, and 0.638$\pm$0.015, respectively. From results for 28 M dwarfs analyzed homogeneously from APOGEE spectra, we find exoplanet-hosting M dwarfs exhibit a C/O abundance ratio approximately 0.01 to 0.05 higher than those with non-detected exoplanets, at limits of a statistically significant offset. A linear regression of [Fe/H] \textit{vs.} C/O distribution reveals a noticeable difference in the angular coefficient between FGK dwarfs (0.27) and M dwarfs (0.13). Assuming our abundance ratios of Ca/Mg, Si/Mg, Al/Mg, and Fe/Mg, we determine a mass of 3.276$^{+0.448}_{-0.419}$$M_{\oplus}$ for TOI-2445 b, having density (6.793$^{+0.005}_{-0.099}$ g.cm$^{-3}$) and core mass fraction (0.329$_{-0.049}^{+0.028}$) very similar to Earth's. We also present an atlas of 113 well-defined spectral lines to analyze M dwarfs in the $H$-band and a comprehensive evaluation of uncertainties from variations in the atmospheric parameters, signal-to-noise, and pseudo-continuum.

astro-ph.SR↗

arXiv2023

A Combined Ground-based and JWST Atmospheric Retrieval Analysis: Both IGRINS and NIRSpec Agree The Atmosphere of WASP-77A b is Metal-Poor

Ground-based, high-resolution and space-based, low-resolution spectroscopy are the two main avenues through which transiting exoplanet atmospheres are studied. Both methods provide unique strengths and shortcomings, and combining the two can be a powerful probe into an exoplanet's atmosphere. Within a joint atmospheric retrieval framework, we combined JWST NIRSpec/G395H secondary eclipse spectra and Gemini South/IGRINS pre- and post-eclipse thermal eclipse observations of the hot Jupiter WASP-77A b. Our inferences from the IGRINS and NIRSpec data sets are consistent with each other, and combining the two allows us to measure the gas abundances of H$_2$O and CO as well as the vertical thermal structure with higher precision than either data set provided individually. We confirm WASP-77A b's subsolar metallicty ([(C+O)/H]=-0.61$^{+0.10}_{-0.09}$) and solar C/O ratio (C/O = 0.57$^{+0.06}_{-0.06}$). The two types of data are complementary, and our abundance inferences are mostly driven by the IGRINS data while inference of the thermal structure is driven by the NIRSpec data. Our ability to draw inferences from the post-eclipse IGRINS data is highly sensitive to the number of singular values removed in the detrending process, potentially due to high and variable humidity. We also search for signatures for atmospheric dynamics in the IGRINS data and find that propagated ephemeris error can manifest as both an orbital eccentricity or a strong equatorial jet. Neither are detected when using more up-to-date ephemerides. However, we find moderate evidence of thermal inhomogeneity and measure a cooler nightside that presents itself in the later phases after secondary eclipse.

astro-ph.EP↗

arXiv2023

Identification of the Top TESS Objects of Interest for Atmospheric Characterization of Transiting Exoplanets with JWST

JWST has ushered in an era of unprecedented ability to characterize exoplanetary atmospheres. While there are over 5,000 confirmed planets, more than 4,000 TESS planet candidates are still unconfirmed and many of the best planets for atmospheric characterization may remain to be identified. We present a sample of TESS planets and planet candidates that we identify as "best-in-class" for transmission and emission spectroscopy with JWST. These targets are sorted into bins across equilibrium temperature $T_{\mathrm{eq}}$ and planetary radius $R{_\mathrm{p}}$ and are ranked by transmission and emission spectroscopy metric (TSM and ESM, respectively) within each bin. In forming our target sample, we perform cuts for expected signal size and stellar brightness, to remove sub-optimal targets for JWST. Of the 194 targets in the resulting sample, 103 are unconfirmed TESS planet candidates, also known as TESS Objects of Interest (TOIs). We perform vetting and statistical validation analyses on these 103 targets to determine which are likely planets and which are likely false positives, incorporating ground-based follow-up from the TESS Follow-up Observation Program (TFOP) to aid the vetting and validation process. We statistically validate 23 TOIs, marginally validate 33 TOIs to varying levels of confidence, deem 29 TOIs likely false positives, and leave the dispositions for 4 TOIs as inconclusive. 14 of the 103 TOIs were confirmed independently over the course of our analysis. We provide our final best-in-class sample as a community resource for future JWST proposals and observations. We intend for this work to motivate formal confirmation and mass measurements of each validated planet and encourage more detailed analysis of individual targets by the community.

astro-ph.EP↗

arXiv2023

A First Look at the JWST MIRI/LRS Phase Curve of WASP-43b

We observed a full-orbit phase curve of the hot Jupiter WASP-43b with MIRI/LRS as part of the Transiting Exoplanet Community Early Release Science Program. Here we report preliminary findings for the instrument performance from the team's MIRI Working Group. Overall we find that MIRI's performance for phase curve observations is excellent, with a few minor caveats. The key takeaways for Cycle 2 planning with MIRI/LRS are: (1) long-duration observations (> 24 hours) have now been successfully executed; (2) for phase curves, we recommend including a one-hour burn-in period prior to taking science data to mitigate the effects of the ramp systematic; and (3) we do not yet recommend partial phase curve observations. In addition, we also find that: the position of the spectrum on the detector is stable to within 0.03 pixels over the full 26.5-hour observation; the light curves typically show a systematic downward ramp that is strongest for the first 30 minutes, but continues to decay for hours; from 10.6-11.8 microns, the ramp effect has remarkably different behavior, possibly due to a different illumination history for the affected region of the detector; after trimming the integrations most affected by the initial ramps and correcting the remaining systematics with analytic models, we obtain residuals to the light-curve fits that are typically within 25% of the photon noise limit for 0.5-micron spectroscopic bins; non-linearity correction is not a significant source of additional noise for WASP-43, though it may be an issue for brighter targets; the gain value of 5.5 electrons/DN currently on CRDS and JDox is known to be incorrect, and the current best estimate for the gain is approximately 3.1 electrons/DN; new reference files for the JWST calibration pipeline reflecting these findings are under development at STScI.

astro-ph.IM↗

arXiv2022

Measuring the Obliquities of the TRAPPIST-1 Planets with MAROON-X

A star's obliquity with respect to its planetary system can provide us with insight into the system's formation and evolution, as well as hinting at the presence of additional objects in the system. However, M dwarfs, which are the most promising targets for atmospheric follow-up, are underrepresented in terms of obliquity characterization surveys due to the challenges associated with making precise measurements. In this paper, we use the extreme-precision radial velocity spectrograph MAROON-X to measure the obliquity of the late M dwarf TRAPPIST-1. With the Rossiter-McLaughlin effect, we measure a system obliquity of $-2^{+17}_{-19}$ degrees and a stellar rotational velocity of 2.1 $\pm$ 0.3 km s$^{-1}$. We were unable to detect stellar surface differential rotation, and we found that a model in which all planets share the same obliquity was favored by our current data. We were unable to make a detection of the signatures of the planets using Doppler tomography, which is likely a result of the both the slow rotation of the star and the low SNR of the data. Overall, TRAPPIST-1 appears to have a low obliquity, which could imply that the system has a low primordial obliquity. It also appears to be a slow rotator, which is consistent with past characterizations of the system and estimates of the star's rotation period. The MAROON-X data allow for a precise measurement of the stellar obliquity through the Rossiter-McLaughlin effect, highlighting the capabilities of MAROON-X and its ability to make high-precision RV measurements around late, dim stars.

astro-ph.EP↗

arXiv2022

Report on Community Cadence Observing to Maximize the Scientific Output of the Keck Planet Finder

The arrival of the Keck Planet Finder (KPF) in 2022 represents a major advance in the precision radial velocity (PRV) capabilities of the W. M. Keck Observatory. In preparation for KPF science, our committee of PRV experts and WMKO staff studied the current implementation of cadence observing at Keck and other PRV facilities. We find that many of KPF's major science cases are not feasible through Keck's standard allocations of full or half nights to individual PIs. Pooling time among several PIs as is currently done by the California Planet Search (CPS) collaboration with HIRES results in lower quality science results than is possible when KPF is available at higher observational cadence. This strategy also creates barriers to entry, particularly for researchers wishing to lead small proposals. This report makes recommendations for optimizing PRV cadence at Keck subject to the following constraints: preservation of clear boundaries between cadence observations and classically scheduled time; and ensuring fairness and scientific independence of different Keck TACs and different KPF PIs. We recommend establishing a new category of Keck time allocation, "KPF Community Cadence" (KPF-CC). In many ways, KPF-CC will formalize observing strategies provided by CPS, but with higher observational cadence appropriate for KPF science and with universal access to the program for all Keck users. We recommend that KPF-CC time be scheduled classically into blocks as small as a quarter night subject to considerations of bright/dark time, variations in proposal pressure with the seasons, and the needs of non-KPF observing programs. Within KPF-CC time, the Keck Observing Assistants would execute observations generated by a dynamic scheduler. We recommend that Keck staff and a board of PRV experts design and maintain the scheduling software.

astro-ph.IM↗

arXiv2022

A close-in puffy Neptune with hidden friends: The enigma of TOI 620

We present the validation of a transiting low-density exoplanet orbiting the M2.5 dwarf TOI 620 discovered by the NASA TESS mission. We utilize photometric data from both TESS and ground-based follow-up observations to validate the ephemerides of the 5.09-day transiting signal and vet false positive scenarios. High-contrast imaging data are used to resolve the stellar host and exclude stellar companions at separations $\gtrsim 0.2''$. We obtain follow-up spectroscopy and corresponding precise radial velocities (RVs) with multiple PRV spectrographs to confirm the planetary nature of the transiting exoplanet. We calculate a 5$\sigma$ upper limit of $M_P < 7.1$ M$_\oplus$ and $\rho_P < 0.74$ g cm$^{-3}$, and we identify a non-transiting 17.7-day candidate. We also find evidence for a substellar (1-20 M$_{\rm J}$) companion with a projected separation $\lesssim 20$ au from a combined analysis of Gaia, AO imaging, and RVs. With the discovery of this outer companion, we carry out a detailed exploration of the possibilities that TOI 620 b might instead be a circum-secondary planet or a pair of eclipsing binary stars orbiting the host in a hierarchical triple system. We find, under scrutiny, that we can exclude both of these scenarios from the multi-wavelength transit photometry, thus validating TOI 620 b as a low-density exoplanet transiting the central star in this system. The low density of TOI 620 b makes it one of the most amenable exoplanets for atmospheric characterization, such as with JWST and Ariel, validated or confirmed by the TESS mission to date.

astro-ph.EP↗

arXiv2022

A New Analysis of 8 Spitzer Phase Curves and Hot Jupiter Population Trends: Qatar-1b, Qatar-2b, WASP-52b, WASP-34b, and WASP-140b

With over 30 phase curves observed during the warm Spitzer mission, the complete data set provides a wealth of information relating to trends and three-dimensional properties of hot Jupiter atmospheres. In this work we present a comparative study of seven new Spitzer phase curves for four planets with equilibrium temperatures of T$_{eq}\sim$ 1300K: Qatar-2b, WASP-52b, WASP-34b, and WASP-140b, as well as the reanalysis of the 4.5 $\micron$ Qatar-1b phase curve due to the similar equilibrium temperature. In total, five 4.5 $\micron$ phase curves and three 3.6 $\micron$ phase curves are analyzed here with a uniform approach. Using these new results, in combination with literature values for the entire population of published Spitzer phase curves of hot Jupiters, we present evidence for a linear trend of increasing hot spot offset with increasing orbital period, as well as observational evidence for two classes of planets in apparent redistribution vs. equilibrium temperature parameter space, and tentative evidence for a dependence of hot spot offset on planetary surface gravity in our $\sim$ 1300 K sample. We do not find trends in apparent heat redistribution with orbital period or gravity. Non-uniformity in literature Spitzer data analysis techniques precludes a definitive determination of the sources or lack of trends.

astro-ph.EP↗

arXiv2021

Assessing $TESS$'s Yield of Rocky Planets Around Nearby M Dwarfs

Terrestrial planets are easier to detect around M dwarfs than other types of stars, making them promising for next-generation atmospheric characterization studies. The $TESS$ mission has greatly increased the number of known M dwarf planets that we can use to perform population studies, allowing us to explore how the rocky planet occurrence rate varies with host radius, following in the footsteps of past work with $Kepler$ data. In this paper, we use simulations to assess $TESS$'s yield of small ($0.5\,R_\oplus \,<\,R_p\,<\,2\,R_\oplus$) planet candidates around nearby ($d\,<\,30$ pc) M dwarfs. We highlight the underappreciated fact that while $TESS$ was indeed expected to find a large number of planets around M dwarfs overall, it was not expected to have a high planetary yield for the latest M dwarfs. Furthermore, we find that $TESS$ has detected fewer planets around stars with $R_*\,<\,0.3 R_\odot$ than even was expected (11 observed vs. $24\,\pm\,5$ expected). We find evidence that the photometric noise of stars in the $TESS$ bandpass increases with decreasing radius for M dwarfs. However, this trend cannot explain the observed distribution of planets. Our main conclusions are: (1) the planet occurrence rate likely doesn't increase, and may decrease for the latest M dwarfs; and (2) there are at least 17, and potentially three times that number, transiting planets around nearby late M dwarfs that still won't be detected by the end of $TESS$'s 4th year.

astro-ph.EP↗

arXiv2021

H-Alpha Variability of V1298 Tau c

The 23 Myr system V1298 Tau hosts four transiting planets and is a valuable laboratory for exploring the early stages of planet evolution soon after formation of the star. We observe the innermost planet, V1298 Tau c, during transit using LBT PEPSI to obtain high spectral resolution characterization of escaping material near the H-alpha line. We find no strong evidence for atmospheric material escaping at the orbital velocity of the planet. Instead, we find a deep stellar feature that is variable on the few percent level, similar to a previous observation of the planet and can be explained by stellar activity. We attempted to monitor the broadband optical transit with LBT MODS but do not achieve the precision needed to characterize the atmosphere or improve the ephemeris.

astro-ph.EP↗

arXiv2021

Randomization Inference of Periodicity in Unequally Spaced Time Series with Application to Exoplanet Detection

The estimation of periodicity is a fundamental task in many scientific areas of study. Existing methods rely on theoretical assumptions that the observation times have equal or i.i.d. spacings, and that common estimators, such as the periodogram peak, are consistent and asymptotically normal. In practice, however, these assumptions are unrealistic as observation times usually exhibit deterministic patterns -- e.g., the nightly observation cycle in astronomy -- that imprint nuisance periodicities in the data. These nuisance signals also affect the finite-sample distribution of estimators, which can substantially deviate from normality. Here, we propose a set identification method, fusing ideas from randomization inference and partial identification. In particular, we develop a sharp test for any periodicity value, and then invert the test to build a confidence set. This approach is appropriate here because the construction of confidence sets does not rely on assumptions of regular or well-behaved asymptotics. Notably, our inference is valid in finite samples when our method is fully implemented, while it can be asymptotically valid under an approximate implementation designed to ease computation. Empirically, we validate our method in exoplanet detection using radial velocity data. In this context, our method correctly identifies the periodicity of the confirmed exoplanets in our sample. For some other, yet unconfirmed detections, we show that the statistical evidence is weak, which illustrates the failure of traditional statistical techniques. Last but not least, our method offers a constructive way to resolve these identification issues via improved observation designs. In exoplanet detection, these designs suggest meaningful improvements in identifying periodicity even when a moderate amount of randomization is introduced in scheduling radial velocity measurements.

stat.ME↗

arXiv2021

The Dark World: A Tale of WASP-43b in Reflected Light with HST WFC3/UVIS

Optical, reflected light eclipse observations provide a direct probe of the exoplanet scattering properties, such as from aerosols. We present here the photometric, reflected light observations of WASP-43b using the HST WFC3/UVIS instrument with the F350LP filter (346-822nm) encompassing the entire optical band. This is the first reflected light, photometric eclipse using UVIS in scanning mode; as such we further detail our scanning extraction and analysis pipeline Arctor. Our HST WFC3/UVIS eclipse light curve for WASP-43 b derived a 3-{\sigma} upper limit of 67 ppm on the eclipse depth, which implies that WASP-43b has a very dark dayside atmosphere. With our atmospheric modeling campaign, we compared our reflected light constraints with predictions from global circulation and cloud models, benchmarked with HST and Spitzer observations of WASP-43b. We infer that we do not detect clouds on the dayside within the pressure levels probed by HST WFC3/UVIS with the F350LP filter (P > 1 bar). This is consistent with the GCM predictions based on previous WASP-43b observations. Dayside emission spectroscopy results from WASP-43b with HST and Spitzer observations are likely to not be significantly affected by contributions from cloud particles.

astro-ph.EP↗

arXiv2020

Keys of a Mission to Uranus or Neptune, the Closest Ice Giants

Uranus and Neptune are the archetypes of "ice giants", a class of planets that may be among the most common in the Galaxy. They hold the keys to understand the atmospheric dynamics and structure of planets with hydrogen atmospheres inside and outside the solar system; however, they are also the last unexplored planets of the Solar System. Their atmospheres are active and storms are believed to be fueled by methane condensation which is both extremely abundant and occurs at low optical depth. This means that mapping temperature and methane abundance as a function of position and depth will inform us on how convection organizes in an atmosphere with no surface and condensates that are heavier than the surrounding air, a general feature of giant planets. Owing to the spatial and temporal variability of these atmospheres, an orbiter is required. A probe would provide a reference atmospheric profile to lift ambiguities inherent to remote observations. It would also measure the abundances of noble gases which can be used to reconstruct the history of planet formation in the Solar System. Finally, mapping the planets' gravity and magnetic fields will be essential to constrain their global composition, atmospheric dynamics, structure and evolution. An exploration of Uranus or Neptune will be essential to understand these planets and will also be key to constrain and analyze data obtained at Jupiter, Saturn, and for numerous exoplanets with hydrogen atmospheres.

astro-ph.IM↗