Solar System Objects Research Articles

Custom JWST NIRSpec/IFU and MIRI/MRS Data Reduction Pipelines for Solar System Targets

We present custom JWST data reduction pipelines for JWST NIRSpec/IFU and MIRI/MRS observations of solar system objects. The pipelines simplify the process of reducing the JWST observations, and include custom steps to significantly improve the data quality. Our custom processing routines include a “desaturation” routine to reduce the effect of saturation while still maintaining high signal-to-noise ratio, and custom flat field correction code to remove the significant artifacts found in MIRI/MRS observations. The pipelines also automatically generate a series of quick look plots and animations to simplify exploration of a dataset. These custom JWST pipelines can be downloaded from https://github.com/JWSTGiantPlanets/pipelines.

Planetesimals at DZ stars – I. Chondritic compositions and a massive accretion event

ABSTRACT There is a wealth of evidence to suggest that planetary systems can survive beyond the main sequence. Most commonly, white dwarfs are found to be accreting material from tidally disrupted asteroids, whose bulk compositions are reflected by the metals polluting the stellar photospheres. While many examples are known, most lack the deep, high-resolution data required to detect multiple elements, and thus characterize the planetesimals that orbit them. Here, spectra of seven DZ white dwarfs observed with Keck High Resolution Echelle Spectrometer (HIRES) are analysed, where up to nine metals are measured per star. Their compositions are compared against those of Solar system objects, working in a Bayesian framework to infer or marginalize over the accretion history. All of the stars have been accreting primitive material, similar to chondrites, with hints of a Mercury-like composition at one star. The most polluted star is observed several Myr after its last major accretion episode, in which a Moon-sized object met its demise.

Timing and Abundance of Clathrate Formation Control Ocean Evolution in Outer Solar System Bodies: Challenges of Maintaining a Thick Ocean within Pluto

Clathrate hydrates may represent a sizable fraction of material within the icy shells of Kuiper Belt objects and icy moons. They influence the chemical and thermal evolution of subsurface oceans by locking volatiles into the ice shell and by providing more thermal insulation than pure water ice. We model the formation of these crystalline compounds in conditions relevant to outer solar system objects, using Pluto as an example. Although Pluto may have hosted a thick ocean in its early history, Pluto’s overall heat budget is probably insufficient to preserve liquid today if its outer shell is pure water ice. One previously proposed reconciliation is that Pluto’s ocean has a winter jacket: an insulating layer of methane clathrate hydrates. Unfortunately, assessments of the timing, quantity, and type of clathrate hydrates forming within planetary bodies are lacking. Our work quantifies the abundance of clathrate-forming gases present in Pluto’s ocean from accreted ices and volatiles released during thermal metamorphism throughout Pluto’s history. We find that if Pluto formed with the same relative abundances of ices found in comets, then a buoyant layer of mixed methane and carbon dioxide clathrate hydrates may form above Pluto’s ocean, though we find it insufficient to preserve a thick ocean today. In general, our study provides methodology for predicting clathrate formation in ocean worlds, which is necessary to predict the evolution of the ocean’s composition and whether a liquid layer remains at present.

Cloud reflection modelling for impact flashes on Jupiter

Aims. We investigate the optical characteristics of flashes caused by the impact of metre- to decametre-sized outer Solar System objects on Jupiter, and the contributions of reflected light from surface clouds at visible wavelengths, in order to estimate more accurate bulk parameters, such as the luminous energy of the flash, the kinetic energy, the mass, and the size of the impact object. Methods. Using the results of recent reflectivity studies of the Jovian surface, we developed a cloud reflection model that calculates the contribution of the reflected light relative to that directly from the flash. We compared the apparent luminous energy of the previously reported flashes with the expected cloud reflection contributions to obtain their revised bulk parameters. Results. We find that cloud reflection contributions can make up to 200% of the flux directly from the flash, and thus can be the most significant uncertainty in the measurement of the bulk parameters. The reflection contributions strongly depend on wavelength. With our cloud reflection correction, we obtained revised bulk parameters for the previously reported flashes. Conclusions. Our cloud reflection correction enables us to better understand the properties of objects impacting Jupiter and is crucial for ongoing detailed investigations using high-sensitivity and multi-wavelength observation systems, such as PONCOTS. It will also be useful for understanding other optical transients in Jupiter’s upper atmosphere, such as the recently discovered sprite-like events.

Astrometry via close approach events: applications to main-belt asteroid (702) Alauda

ABSTRACT The release of Gaia catalogue is revolutionary to the astronomy of Solar system objects. After some effects such as atmospheric refraction and CCD geometric distortion have been taken into account, the astrometric precision for ground-based telescopes can reach the level of tens of milli-arcseconds (mas). If an object approaches a reference star in a small relative angular distance (less than 100 arcsec), which is called close approach event in this work, the relative positional precision between the object and reference star will be further improved since the systematic effects of atmospheric turbulence and local telescope optics can be reduced. To obtain the precise position of a main-belt asteroid in an close approach event, a second-order angular velocity model with time is supposed in the sky plane. By fitting the relationship between the relative angular distance and observed time, we can derive the time of maximum approximation and calculate the corresponding position of the asteroid. In practice, five nights’ CCD observations including 15 close approach events of main-belt asteroid (702) Alauda are taken for testing by the 1 m telescope at Yunnan Observatory, China. Compared with conventional solutions, our results show that the positional precision significantly improves, which reaches better than 4 mas, and 1 mas in the best case when referenced for the Jet Propulsion Laboratory (JPL) ephemeris in both right ascension and declination.

Triton's photochemical model: Update

Titan, Triton, and Pluto are the Solar System objects with the nitrogen-ethane atmospheres. The progress in Titan's photochemistry, stimulated by the very successful Cassini-Huygens mission, facilitated photochemical interpretation of Pluto's atmosphere that was observed by the New Horizons mission and supporting ground-based measurements. Here is an update of Triton's atmospheric and ionospheric photochemistry that combines the previous photochemical model (Krasnopolsky and Cruikshank 1995, Photochemistry of Triton's atmosphere and ionosphere, J. Geophys. Res. 100, 21,271-21,286) with findings in Titan's and Pluto's photochemistry and progress in chemical kinetics.Our modeling of Triton's photochemistry is restricted to the conditions of the Voyager 2 flyby in 1989, when data on vertical profiles of temperature, haze, and densities of N2, CH4, N, and electrons were obtained using radio- and solar UVS occultations and imaging.Significant differences between the composition and photochemistry of Triton's atmosphere and those of Titan and Pluto are mostly caused by the low CH4 tropospheric abundance of 100 ppm, smaller than those on Titan and Pluto by two orders of magnitude. This methane is strongly depleted photochemically to a ppb level in the upper atmosphere of Triton, while it is enriched by diffusive separation on Titan and Pluto. Therefore atomic species and their chemistry are much more abundant on Triton than on Titan and Pluto. Atomic ions C+ and N+ with slow recombination rates dominate in Triton's ionosphere with electron densities, significantly exceeding those on Titan and Pluto.The proposed model agrees with all observational constraints and presumes thermal escape of H2 + H with a rate of 45 g cm−2 Byr−1, loss of nitrogen of 40 g cm−2 Byr−1 on thermal escape and precipitation of nitriles, and sublimation and loss of methane of 270 g cm−2 Byr−1.C2H6 and HCN are minor species in the photochemical precipitations on Triton, and their detection in Triton's ice may refer to either the primordial composition or ice photochemistry.Seven versions of the model are calculated to study its sensitivity to some basic input parameters. The model can be used for planning future studies of Triton's atmosphere. An analog of the Ion-Neutral Mass Spectrometer onboard Triton's orbiter looks promising.

Complex Ice Chemistry: A comparative study of electron irradiated planetary ice analogues containing methane

Various Solar System objects are covered in layers of ice that are dominated by H2O, CH4, and N2 and in which complex chemical processes take place. In this work, the influence of composition and irradiation duration on the volatile irradiation products of mixed CH4:N2, CH4:H2O, and CH4:H2O:N2 ices after electron irradiation are studied. The ices were irradiated for 2 or 4 h with 5 keV electrons, followed by a temperature programmed desorption, where the desorption of the volatile irradiation products was observed. The formation of C2Hx and C3Hx is observed in all ices and for both irradiation times. For the ices containing H2O, molecules as large as tentatively identified C4Hx and C5Hx are observed to co-desorb with water, whereas for CH4:N2 a continuous desorption signal is observed instead of a sharp desorption peak. A decrease in signal intensity from the 2 to the 4 h irradiation is observed for most m/z signals in CH4:H2O and CH4:H2O:N2 ices, whereas the opposite is recorded for CH4:N2, where in general larger signal for longer irradiation duration is seen. The addition of nitrogen to the CH4:H2O ice did not lead to clear identification of different molecules, but instead to a decrease of the observed signal for complex molecules, suggesting that the addition of nitrogen to the CH4:H2O mixture primarily leads to a more effective incorporation of material in an organic residue. The analysis of the residue will be subject of future work to complement the findings in this study.

On the pollution of white dwarfs by exo-Oort cloud comets

ABSTRACT A large fraction of white dwarfs (WDs) have metal-polluted atmospheres, which are produced by accreting material from remnant planetary systems. The composition of the accreted debris broadly resembles that of rocky Solar system objects. Volatile-enriched debris with compositions similar to long-period comets (LPCs) is rarely observed. We attempt to reconcile this dearth of volatiles with the premise that exo-Oort clouds (XOCs) occur around a large fraction of planet-hosting stars. We estimate the comet accretion rate from an XOC analytically, adapting the ‘loss cone’ theory of LPC delivery in the Solar system. We investigate the dynamical evolution of an XOC during late stellar evolution. Using numerical simulations, we show that 1–30 per cent of XOC objects remain bound after anisotropic stellar mass-loss imparting a WD natal kick of ${\sim}1 \, {\rm km \, s^{-1}}$. We also characterize the surviving comets’ distribution function. Surviving planets orbiting a WD can prevent the accretion of XOC comets by the star. A planet’s ‘dynamical barrier’ is effective at preventing comet accretion if the energy kick imparted by the planet exceeds the comet’s orbital binding energy. By modifying the loss cone theory, we calculate the amount by which a planet reduces the WD’s accretion rate. We suggest that the scarcity of volatile-enriched debris in polluted WDs is caused by an unseen population of 10–$100 \, \mathrm{au}$ scale giant planets acting as barriers to incoming LPCs. Finally, we constrain the amount of volatiles delivered to a planet in the habitable zone of an old, cool WD.

Physical Properties of the Asteroid Belts from Brightness-limited Surveys

We introduce a general debiasing Bayesian formalism to brightness-limited surveys of solar system objects that constrains the statistical distribution of a population’s physical characteristics such as size, albedo, heliocentric distance, or others to account for the survey detections and measured properties such as brightness. We reanalyze the Dark Energy Camera search for main-belt asteroids of Peña et al. and fit a smooth double power-law size to its size distribution. Using only detections with reliable distances and accurate orbital information, we find no evidence for a significant difference in size distribution between the inner, middle, and outer belts for objects between 0.1 and 1 km in diameter, with q 2 = 2.27 ± 0.05 a good fit for the small-end slope. We show that the intrinsic number density of objects is consistent between these populations and is compatible with observational biases. As spectral classes are distributed unevenly throughout the main belt, these results support the ongoing collisional reprocessing of the asteroid belt for objects smaller than 5 km.

Isotopic Enrichment of Planetary Systems from Asymptotic Giant Branch Stars

Abstract Short-lived radioisotopes, in particular 26Al and 60Fe, are thought to contribute to the internal heating of the Earth, but are significantly more abundant in the solar system compared to the interstellar medium. The presence of their decay products in the oldest solar system objects argues for their inclusion in the Sun’s protoplanetary disk almost immediately after the star formation event that formed the Sun. Various scenarios have been proposed for their delivery to the solar system, usually involving one or more core-collapse supernovae of massive stars. An alternative scenario involves the young Sun encountering an evolved asymptotic giant branch (AGB) star. AGBs were previously discounted as a viable enrichment scenario for the solar system due to the presumed low probability of an encounter between an old, evolved star and a young pre-main-sequence star. We report the discovery in Gaia data of an interloping AGB star in the star-forming region NGC2264, demonstrating that old, evolved stars can encounter young forming planetary systems. We use simulations to calculate the yields of 26Al and 60Fe from AGBs and their contribution to the long-term geophysical heating of a planet, and find that these are comfortably within the range previously calculated for the solar system.

GaiaData Release 3

Context.TheGaiamission of the European Space Agency (ESA) has been routinely observing Solar System objects (SSOs) since the beginning of its operations in August 2014. TheGaiadata release three (DR3) includes, for the first time, the mean reflectance spectra of a selected sample of 60 518 SSOs, primarily asteroids, observed between August 5, 2014, and May 28, 2017. Each reflectance spectrum was derived from measurements obtained by means of the Blue and Red photometers (BP/RP), which were binned in 16 discrete wavelength bands. For every spectrum, the DR3 also contains additional information about the data quality for each band.Aims.We describe the processing of theGaiaspectral data of SSOs, explaining both the criteria used to select the subset of asteroid spectra published inGaiaDR3, and the different steps of our internal validation procedures. In order to further assess the quality ofGaiaSSO reflectance spectra, we carried out external validation against SSO reflectance spectra obtained from ground-based and space-borne telescopes and available in the literature; we present our validation approach.Methods.For each selected SSO, an epoch reflectance was computed by dividing the calibrated spectrum observed by the BP/RP at each transit on the focal plane by the mean spectrum of a solar analogue. The latter was obtained by averaging theGaiaspectral measurements of a selected sample of stars known to have very similar spectra to that of the Sun. Finally, a mean of the epoch reflectance spectra was calculated in 16 spectral bands for each SSO.Results.GaiaSSO reflectance spectra are in general agreement with those obtained from a ground-based spectroscopic campaign specifically designed to cover the same spectral interval asGaiaand mimic the illumination and observing geometry characterisingGaiaSSO observations. In addition, the agreement betweenGaiamean reflectance spectra and those available in the literature is good for bright SSOs, regardless of their taxonomic spectral class. We identify an increase in the spectral slope of S-type SSOs with increasing phase angle. Moreover, we show that the spectral slope increases and the depth of the 1 μm absorption band decreases for increasing ages of S-type asteroid families. The latter can be interpreted as proof of progressive ageing of S-type asteroid surfaces due to their exposure to space weathering effects.

GaiaData Release 3

Context.The third data release by theGaiamission of the European Space Agency (DR3) is the first release to provide the community with a large sample of observations for more than 150 thousand Solar System objects, including asteroids and natural planetary satellites. The release contains astrometry (over 23 million epochs) and photometry, along with average reflectance spectra of 60518 asteroids and osculating elements.Aims.We present an overview of the procedures that have been implemented over several years of development and tests to process Solar System data at the level of accuracy thatGaiacan reach. We illustrate the data properties and potential with some practical examples.Methods.In order to allow the users ofGaiaDR3 to best exploit the data, we explain the assumptions and approaches followed in the implementation of the data processing pipeline for Solar System processing, and their effects in terms of data filtering, optimisation, and performances. We then test the data quality by analysing post-fit residuals to adjusted orbits, the capacity of detecting subtle dynamical effects (wobbling due to satellites or shape and Yarkovsky acceleration), and to reproduce known properties of asteroid photometry (phase curves and rotational light curves).Results.The DR3 astrometric accuracy is a clear improvement over the data published in DR2, which concerned a very limited sample of asteroids. The performance of the data reduction is met, and is illustrated by the capacity of detecting milliarcsecond-level wobbling of the asteroid photocentre that is due to satellite or shape effects and contributes to Yarkovsky effect measurements.Conclusions.The third data release can in terms of data completeness and accuracy be considered the first full-scale realisation of the Solar System survey byGaia.

GaiaData Release 3

Context.We present the third data release of the European Space Agency’sGaiamission,GaiaDR3. This release includes a large variety of new data products, notably a much expanded radial velocity survey and a very extensive astrophysical characterisation ofGaiasources.Aims.We outline the content and the properties ofGaiaDR3, providing an overview of the main improvements in the data processing in comparison with previous data releases (where applicable) and a brief discussion of the limitations of the data in this release.Methods.TheGaiaDR3 catalogue is the outcome of the processing of raw data collected with theGaiainstruments during the first 34 months of the mission by theGaiaData Processing and Analysis Consortium.Results.TheGaiaDR3 catalogue contains the same source list, celestial positions, proper motions, parallaxes, and broad band photometry in theG,GBP, andGRPpass-bands already present in the Early Third Data Release,GaiaEDR3.GaiaDR3 introduces an impressive wealth of new data products. More than 33 million objects in the rangesGRVS < 14 and 3100 < Teff < 14 500, have new determinations of their mean radial velocities based on data collected byGaia. We provideGRVSmagnitudes for most sources with radial velocities, and a line broadening parameter is listed for a subset of these. MeanGaiaspectra are made available to the community. TheGaiaDR3 catalogue includes about 1 million mean spectra from the radial velocity spectrometer, and about 220 million low-resolution blue and red prism photometer BP/RP mean spectra. The results of the analysis of epoch photometry are provided for some 10 million sources across 24 variability types.GaiaDR3 includes astrophysical parameters and source class probabilities for about 470 million and 1500 million sources, respectively, including stars, galaxies, and quasars. Orbital elements and trend parameters are provided for some 800 000 astrometric, spectroscopic and eclipsing binaries. More than 150 000 Solar System objects, including new discoveries, with preliminary orbital solutions and individual epoch observations are part of this release. Reflectance spectra derived from the epoch BP/RP spectral data are published for about 60 000 asteroids. Finally, an additional data set is provided, namely theGaiaAndromeda Photometric Survey, consisting of the photometric time series for all sources located in a 5.5 degree radius field centred on the Andromeda galaxy.Conclusions.This data release represents a major advance with respect toGaiaDR2 andGaiaEDR3 because of the unprecedented quantity, quality, and variety of source astrophysical data. To date this is the largest collection of all-sky spectrophotometry, radial velocities, variables, and astrophysical parameters derived from both low- and high-resolution spectra and includes a spectrophotometric and dynamical survey of SSOs of the highest accuracy. The non-single star content surpasses the existing data by orders of magnitude. The quasar host and galaxy light profile collection is the first such survey that is all sky and space based. The astrophysical information provided inGaiaDR3 will unleash the full potential ofGaia’s exquisite astrometric, photometric, and radial velocity surveys.

ZZ Ceti stars of the southern ecliptic hemisphere re-observed by TESS

Context. In 2020, a publication presented the first-light results for 18 known ZZ Ceti stars observed by the TESS Space Telescope during the first survey observations of the southern ecliptic hemisphere. However, in the meantime, new measurements have become available from this field, in many cases with the new, 20 s ultrashort cadence mode. Aims. We investigated the similarities and differences in the pulsational behaviour of the observed stars between the two observational seasons, and searched for new pulsation modes for asteroseismology. Methods. We performed Fourier analysis of the light curves using the standard pre-whitening process, and compared the results with frequencies obtained from the earlier data. Utilising the 2018 version of the White Dwarf Evolution Code, we also performed an asteroseismic analysis of the different stars. We searched for models with seismic distances in the vicinity of the Gaia geometric distances. Results. We detected several new possible pulsation modes of the studied pulsators. In the case of HE 0532-5605, we found a similar brightening phase to the one presented in the 2020 first-light paper, which means this phenomenon is recurring. Therefore, HE 0532-5605 appears to be a new outbursting DAV star. We also detected a lower-amplitude brightening phase in the star WD J0925+0509. However, this case has proven to be the result of the passage of a Solar System object in the foreground. We accept asteroseismic model solutions for six stars.

GaiaData Release 3

Context.Blue (BP) and Red (RP) Photometer low-resolution spectral data are one of the exciting new products inGaiaData Release 3 (GaiaDR3). These data have also been used to derive astrometry and integrated photometry inGaiaEarly Data Release 3 and astrophysical parameters and Solar System object reflectance spectra inGaiaDR3.Aims.In this paper, we give an overview of the processing techniques that allow raw satellite data of multiple transits per source to be converted into combined spectra calibrated to an internal reference system, resulting in low-resolution BP and RP mean spectra. We describe how we overcome challenges due to the complexity of the on-board instruments and to the various observation strategies. Furthermore, we show highlights from our scientific validation of the results. This work covers the internal calibration of BP/RP spectra to a self-consistent mean instrument, while the calibration of the BP/RP spectra to the absolute reference system of physical flux and wavelength is covered by one of the accompanyingGaiaDR3 papers.Methods.We calibrate about 65 billion individual transit spectra onto the same mean BP/RP instrument through a series of calibration steps, including background subtraction, calibration of the CCD geometry, and an iterative procedure for the calibration of CCD efficiency as well as variations of the line-spread function and dispersion across the focal plane and in time. The calibrated transit spectra are then combined for each source in terms of an expansion into continuous basis functions. We discuss the configuration of these basis functions.Results.Time-averaged mean spectra covering the optical to near-infrared wavelength range [330, 1050] nm are published for approximately 220 million objects. Most of these are brighter thanG = 17.65 but some BP/RP spectra are published for sources down toG = 21.43. Their signal-to-noise ratio (S/N) varies significantly over the wavelength range covered, and with magnitude and colour of the observed objects, with sources aroundG = 15 having a S/N above 100 in some wavelength ranges. The top-quality BP/RP spectra are achieved for sources with magnitudes 9 < G < 12, with S/N reaching 1000 in the central part of the RP wavelength range. Scientific validation suggests that the internal calibration was generally successful. However, there is some evidence for imperfect calibrations at the bright endG < 11, where calibrated BP/RP spectra can exhibit systematic flux variations that exceed their estimated flux uncertainties. We also report that, due to long-range noise correlations, BP/RP spectra can exhibit wiggles when sampled in pseudo-wavelength.Conclusions.TheGaiaDR3 data products are the expansion coefficients and corresponding covariance matrices for BP and RP separately. Users are encouraged to work with the data in this format, with full covariance information showing that correlations between coefficients are typically very low. Documentation and instructions on how to access and use BP/RP spectral data from the archive are also provided.

GaiaData Release 3

Context.The thirdGaiadata release (DR3) provides a wealth of new data products. The early part of the release,GaiaEDR3, already provided the astrometric and photometric data for nearly two billion sources. The full release now adds improved parameters compared toGaiaDR2 for radial velocities, astrophysical parameters, variability information, light curves, and orbits for Solar System objects. The improvements are in terms of the number of sources, the variety of parameter information, precision, and accuracy. For the first time,GaiaDR3 also provides a sample of spectrophotometry and spectra obtained with the Radial Velocity Spectrometer, binary star solutions, and a characterisation of extragalactic object candidates.Aims.Before the publication of the catalogue, these data have undergone a dedicated transversal validation process. The aim of this paper is to highlight limitations of the data that were found during this process and to provide recommendations for the usage of the catalogue.Methods.The validation was obtained through a statistical analysis of the data, a confirmation of the internal consistency of different products, and a comparison of the values to external data or models.Results.GaiaDR3 is a new major step forward in terms of the number, diversity, precision, and accuracy of theGaiaproducts. As always in such a large and complex catalogue, however, issues and limitations have also been found. Detailed examples of the scientific quality of theGaiaDR3 release can be found in the accompanying data-processing papers as well as in the performance verification papers. Here we focus only on the caveats that the user should be aware of to scientifically exploit the data.

Look Up (Again) The Apophis Asteroid: Simulating and Visualizing Orbit

The asteroid Apophis, first discovered in 2004 by American astronomers, is known to have a dangerous potential for planet Earth. Many early studies predict that in 2029 it will experience a close encounter and have a possible collision with the Earth at the next close encounter due to keyhole gravity. This research will explain how to carry out an orbit simulation using an orbit integrator to review this possibility and the evolution of the Apophis asteroid orbit over the next 500 years. The results of this study are expected to provide an understanding of simulating asteroid orbit from its orbital parameters and to build awareness of the threat of danger from small solar system objects such as asteroids, comets, and meteoroids.

Mathematical Methods for an Accurate Navigation of the Robotic Telescopes

Accurate sky identification is one of the most important functions of an automated telescope mount. The more accurately the robotic telescope is navigated to the investigated part of the sky, the better the observations and discoveries made. In this paper, we present mathematical methods for accurate sky identification (celestial coordinates determination). They include the automatic selection of the reference stars, preliminary and full sky identification, as well as an interaction with international databases, which are a part of the astrometric calibration. All described methods help to receive accurately calculated astrometric data and use it for the positional calibration and better navigation of the automated telescope mount. The developed methods were successfully implemented in the Collection Light Technology (CoLiTec) software. Through its use, more than 1600 small solar system objects were discovered. It has been used in more than 700,000 observations and successful sky identifications, during which, five comets were discovered. Additionally, the accuracy indicators of the processing results of the CoLiTec software are provided in the paper, which shows benefits of the CoLiTec software and lower standard deviation of the sky identification in the case of low signal-to-noise ratios.

Improved prior for adaptive optics point spread function estimation from science images: Application for deconvolution

Context. Access to knowledge of the point spread function (PSF) of adaptive optics(AO)-assisted observations is still a major limitation when processing AO data. This limitation is particularly important when image analysis requires the use of deconvolution methods. As the PSF is a complex and time-varying function, reference PSFs acquired on calibration stars before or after the scientific observation can be too different from the actual PSF of the observation to be used for deconvolution, and lead to artefacts in the final image. Aims. We improved the existing PSF-estimation method based on the so-called marginal approach by enhancing the object prior in order to make it more robust and suitable for observations of resolved extended objects. Methods. Our process is based on a two-step blind deconvolution approach from the literature. The first step consists of PSF estimation from the science image. For this, we made use of an analytical PSF model, whose parameters are estimated based on a marginal algorithm. This PSF was then used for deconvolution. In this study, we first investigated the requirements in terms of PSF parameter knowledge to obtain an accurate and yet resilient deconvolution process using simulations. We show that current marginal algorithms do not provide the required level of accuracy, especially in the presence of small objects. Therefore, we modified the marginal algorithm by providing a new model for object description, leading to an improved estimation of the required PSF parameters. Results. Our method fulfills the deconvolution requirement with realistic system configurations and different classes of Solar System objects in simulations. Finally, we validate our method by performing blind deconvolution with SPHERE/ZIMPOL observations of the Kleopatra asteroid.

In Recognition of Our 2022 Peer Reviewers and Volunteers

AbstractPeer review is the key to ensuring that the articles published in scientific journals such as JGR: Planets are based on sound scientific principles, follow state‐of‐the‐art techniques, and present exciting discoveries or novel understanding of the fundamental processes that affect solar system objects. JGR: Planets covers an extraordinarily broad range of topics addressing every aspect of geoscience with the only requirement that the work addresses planetary processes. The breadth of topics published is reflected by our editorial team composed in 2022 of associate editors Jun Cui, Joel Davis, Leigh Fletcher, Matthias Grott, Ananya Mallik, German Martínez, Molly McCanta, Katarina Miljkovic, Ryan Park, Andrew Poppe, Beatrix Sánchez‐Cano, Mariek Schmidt, Yasuhito Sekine, Kelsi Singer, Sonia Tikoo, David Trang, and Zhiyong Xiao in addition to the editors who authored this note. We rely on the expertise of the community to vet the articles submitted to the journal. In 2022, JGR: Planets benefited from 1,299 reviews provided by 775 unique volunteer reviewers. We also received help from 29 guest editors working on seven active special collections. We know that all our volunteers juggle many duties, both professional and personal. We are forever grateful that they chose to dedicate their time and energy to evaluating submitted manuscripts and advising us on the suitability of each manuscript for our journal, often suggesting ways to improve the paper. Scientific publishing is truly a selfless community effort. The entire editorial board of JGR: Planets wishes to express their most heartfelt gratitude to the many scientists who chose to support their journal. Thank you!