Asteroid Research Articles

On the Spin Dynamics of Elongated Minor Bodies with Applications to a Possible Solar System Analogue Composition for ‘Oumuamua

Abstract The first interstellar object, 1I/2017 U1 (‘Oumuamua), exhibited several unique properties, including an extreme aspect ratio, a lack of typical cometary volatiles, and a deviation from a Keplerian trajectory. Several authors have hypothesized that the non-gravitational acceleration was caused by either cometary outgassing or radiation pressure. Here, we investigate the spin dynamics of ‘Oumuamua under the action of high-surface-area fractional activity and radiation pressure. We demonstrate that a series of transient jets that migrate across the illuminated surface will not produce a secular increase in the spin rate. We produce 3D tumbling simulations that approximate the dynamics of a surface-covering jet and show that the resulting synthetic light curve and periodogram are reasonably consistent with the observations. Moreover, we demonstrate that radiation pressure also produces a steady spin state. While carbon monoxide (CO) has been dismissed as a possible accelerant because of its non-detection in emission by Spitzer, we show that outgassing from a surface characterized by a modest covering fraction of CO ice can satisfy the non-ballistic dynamics for a plausible range of assumed bulk densities and surface albedos. Spitzer upper limits on CO emission are, however, inconsistent with the CO production necessary to provide the acceleration. Nonetheless, an ad hoc but physically plausible explanation is that the activity level varied greatly during the time that the trajectory was monitored. We reproduce the astrometric analysis presented in Micheli et al., and verify that the non-gravitational acceleration was consistent with stochastic changes in outgassing.

Eclogitic metamorphism in the Alpine far-west: petrological constraints on the Banchetta-Rognosa tectonic unit (Val Troncea, Western Alps)

The Banchetta-Rognosa tectonic unit (BRU), covering an area of 10 km2 in the upper Chisone valley, consists of two successions referred to a continental margin (Monte Banchetta succession) and a proximal oceanic domain (Punta Rognosa succession) respectively. In both successions, Mesozoic meta-sedimentary covers discordantly lie on their basement. This paper presents new data on the lithostratigraphy and the metamorphic evolution of the continental basement of the Monte Banchetta succession. It comprises two meta-sedimentary sequences with minor meta-intrusive bodies preserving their original lithostratigraphic configuration, despite the intense Alpine deformation and metamorphic re-equilibration. Phase equilibrium modeling points to a metamorphic eclogitic peak (D1 event) of 20–23 kbar and 440–500 °C, consistent among three different samples, analyzed from suitable lithologies. The exhumation P–T path is characterized by a first decompression of at least 10 kbar, leading to the development of the main regional foliation (i.e. tectono-metamorphic event D2). The subsequent exhumation stage (D3 event) is marked by a further decompression of almost 7–8 kbar associated with a significant temperature decrease (cooling down to 350–400 °C), implying a geothermal gradient compatible with a continental collision regime. These data infer for this unit higher peak P–T conditions than previously estimated with conventional thermobarometry. The comparison of our results with the peak P–T conditions registered by other neighboring tectonic units allows to interpret the BRU as one of the westernmost eclogite-facies unit in the Alps.

DinoSAVR struck by the TAVR asteroids

DinoSAVR struck by the TAVR asteroids

Life in Elliptical Galaxies: Hot Spheroids, Fast Stars, Deadly Comets?

Abstract Elliptical galaxies have dynamically hot (σ 1D ∼100–300 km s−1) populations of stars, and presumably, smaller objects like comets. Because interstellar minor bodies are moving much faster, they hit planets harder and more often than in the local Galaxy. I estimate the rates for Chicxulub-scale impacts on an Earth-size planet in elliptical galaxies as a potential habitability constraint on intelligent life. Around most stars in a normal elliptical galaxy, these planets receive only ∼0.01–0.1 Gyr−1, although hazardous rates may be common in certain compact early-type galaxies and red nuggets. About ∼5% of the stellar mass is in a region where the rate is > 10 Gyr−1, large enough to dominate the mass extinction rate. This suggests that elliptical galaxies have an exclusion zone of order one hundred parsecs in radius around their centers for the evolution of intelligent life.

New data on the reduced intrusion-related Au mineralization of Central Kolyma gold region: age, formation conditions, composition, orecontrolling factors

New data are presented on the formation conditions and ages of the reduced intrusion-related Au mineralization of the Vetrenskaya area in the Central Kolyma region. The mineralization is predominantly confined to intersections of Late Jurassic minor intrusive bodies and NE-trending fracture systems and is represented by zones of thin quartz veinlets with sericite-quartz halos. The major ore mineral is gold-bearing arsenopyrite (up to 10%), while minor minerals are represented by lellingite, pyrite, chalcopyrite, and pyrrhotite. Microscopic native gold of a low fineness is paragenetically associated with bismuth minerals (bismuthine, native bismuth, andtellurides of Bi and Au), forming microinclusions (1–10 μ) in the arsenopyrite. Isochronous Re-Os age of the goldbearing arsenopyrite is 137–117 Ma, which suggests the mineralization was formed significantly later than the hosting granitoids (147–153 Ma). The reduced intrusionrelated Au ore deposit was formed at shallower depths in comparison with orogenic Au deposits, and at lower temperatures in comparison with rare metal (W, Mo) ore deposits.

한국 우주관측 자료 전략 수립 제안

Space observation data includes research data such as stars, galaxies, Sun, space plasma, planets, and minor bodies observed through space missions, including processing and utilizing the observation data. Astronomy and space science observation systems are getting larger, and space mission opportunities and data size are increasing. Accordingly, the need for systematic and efficient management of space observation data is growing. Therefore, in Korea, a strategy and policy for space observation data should be established. As a stage of preparation, National Aeronautics and Space Administration (NASA)’s data strategy, which developed from extensive understanding and long-term experience for space observation data, was analyzed. Based on the analysis results, we propose a strategic direction and 10 recommendations for Korean space observation data strategies that will be the basis for establishing space observation data policies in the future.

Twentieth-century milestones in the history of the Russian ephemeris service: Marking 100 years of the Calculation Institute and astronomical yearbook

This is the history of how the Russian ephemeris service for major and minor bodies of the solar system was created and developed to provide necessary data for the needs of astronomy, as well as ground-based, sea, and space navigation. The background of this presentation is various astronomical events described, as well as the life events of the institutions where the service was carried out.

Eosinophilic Reaction at the Time of Catheter Insertion Predicts Survival in Patients Initiating Peritoneal Dialysis

Introduction: Despite excellent biocompatibility, insertion of silicone peritoneal dialysis (PD) catheters can induce minor foreign body reaction, affecting long-term patient outcomes. We evaluated the effect of eosinophilic reaction associated with PD catheter insertion on outcomes of patients initiating PD. Methods: Eosinophilic reaction to PD catheter insertion was defined as the ratio of peripheral blood eosinophil count at 1 week after insertion (E1W) to pre-insertion eosinophil count (E0), and the association of E1W/E0 with technique survival, peritonitis-free survival, and heart failure (HF)-related hospitalization-free survival was analyzed. Results: This retrospective cohort study included 116 patients (89 male patients) who underwent PD catheter insertion between January 2008 and June 2018 (61.3 ± 12.9 years). The follow-up duration was 46.2 (23.8–75.3) months. E1W was significantly higher than E0 (median, 333 vs. 234/μL, p < 0.001), with a median E1W/E0 of 1.54. The log-rank test showed that technique survival, peritonitis-free survival, and HF-related hospitalization-free survival were significantly better in patients with E1W/E0 < 1.54 than in those with E1W/E0 ≥ 1.54 (p = 0.002, <0.001, and <0.001, respectively). By the Cox regression analysis adjusted for age, sex, the Charlson comorbidity index, the estimated glomerular filtration rate, and the geriatric nutritional risk index, E1W/E0 remained a significant risk factor for technique failure, peritonitis, and hospitalization for HF (hazard ratio (HR) 1.68, p = 0.01; HR 2.19, p < 0.001; HR 2.15, p < 0.001, respectively). Conclusion: Eosinophilic reaction at the time of PD catheter insertion is a novel marker that may predict outcomes in patients initiating PD.

White dwarf planetary debris dependence on physical structure distributions within asteroid belts

ABSTRACT White dwarfs that exhibit transit signatures of planetary debris and accreted planetary material provide exceptional opportunities to probe the material composition and dynamical structure of planetary systems. Although previous theoretical work investigating the role of minor body disruption around white dwarfs has focused on spherical bodies, Solar system asteroids can be more accurately modelled as triaxial ellipsoids. Here, we present an analytical framework to identify the type of disruption (tidal fragmentation, total sublimation, or direct impact) experienced by triaxial asteroids approaching white dwarfs on extremely eccentric (e ∼ 1) orbits. This framework is then used to identify the outcomes for simplified Main belt analogues of 100 bodies across five different white dwarf temperatures. We also present an empirical relationship between cooling age and effective temperature for both DA and DB white dwarfs to identify the age of the white dwarfs considered here. We find that using a purely spherical shape model can underestimate the physical size and radial distance at which an asteroid is subjected to complete sublimation, and these differences increase with greater elongation of the body. Contrastingly, fragmentation always occurs in the largest semi-axis of a body and so can be modelled by a sphere of that radius. Both fragmentation and sublimation are greatly affected by the body’s material composition, and hence by the composition of their progenitor asteroid belts. The white dwarf temperature, and hence cooling age, can affect the expected debris distribution: higher temperatures sublimate large elongated asteroids, and cooler temperatures accommodate more direct impacts.

Anatomy of a mixed bioclastic–siliciclastic regressive tidal sand ridge: Facies‐based case study from the lower Pleistocene Siderno Strait, southern Italy

AbstractSand ridges, a common feature of modern open shelves, reflect persistent currents and sediment availability under recent transgressive conditions. They represent the largest bedforms in the oceans and, as such, can yield information on long‐term oceanographic processes. However, there is a limited number of tidal sand ridges documented from the rock record, examples of regressive tidal sand ridges are scarce and studies describing ridges in straits are even more rare. This study analyses a Gelasian succession within a structurally controlled, tide‐dominated strait in the Siderno Basin, southern Italy. The strait connected two wider basins, and accumulated sediments reworked by amplified tidal (bi‐directional) currents. A series of tidal sand ridges with superimposed dunes developed close to the south‐eastern end of the strait, where bathymetry was deeper and flow expansion occurred. One of the best‐exposed tidal sand ridges, 65 m thick, crops out along a ca 2 km long cliff. Large‐scale, ESE‐prograding, seaward‐offlapping shingles contain sets of bioclastic–siliciclastic, coarse‐grained, cross‐stratified sandstones, erosionally overlying upper Pliocene shelf marls and fine‐grained sandstones. Cross‐strata show angular, tangential and sigmoidal foresets with compound architectures and a SSE migration, i.e. oblique to the main growth direction. Fossil content indicates open‐marine conditions. The succession changes abruptly across an erosion surface to non‐tidal, highly burrowed mixed siliciclastic–bioclastic fine‐grained sandstones, less than 15 m thick. Documented features reflect stages of nucleation, active accretion and abandonment of an individual sand ridge, during a complete cycle of relative sea‐level change. The ridge formed during a phase of normal regression, with accretion occurring during an initial highstand and the ensuing falling stage. During the lowstand the ridge was split into several minor bodies by enhanced tidal currents. The ensuing transgression draped the moribund ridge with tabular strata, whereas final highstand shelf sedimentation reworked the top of the underlying sand body with weak currents.

Dynamical classification of the asteroids in the Hungaria group: The objects affected by the exterior mean-motion resonance 2:3 with Mars

In this paper, we perform a dynamical study of the population of Hungaria asteroids, close to the exterior 2:3 mean-motion resonance (MMR) with Mars. The aim of this work is to initiate a catalog of asteroids captured in mean-motion resonances (MMRs) with Mars in the Hungaria region, by first identifying the minor bodies affected by the 2:3 MMR. To achieve our goal, we follow the temporal evolution of massless test particles by 2 Myr in the proximity of the 2:3 resonance considering the gravitational influence of all planets of the Solar System. We present a semi-analytical model to calculate the extension of the resonant region for a population with the dynamical characteristics of the Hungaria asteroids. We show that the resonance can disturb the asteroids in two ways: by capture or by indirect influence. We find 22 asteroids captured inside the 2:3 MMR and 89 asteroids which exhibit temporary librations around this resonance. The predictions of our model are in good agreement with the numerical results, which make it useful for the study of other MMRs in this region. For asteroids without determined synthetic proper elements, we use the results of our numerical simulations to calculate the mean orbital elements, which can be used as a first approximation of the proper elements.

Thermophysical evolution of planetesimals in the primordial disc

ABSTRACT The primordial disc of small icy planetesimals, once located at 15–$30\, \mathrm{au}$ from the Sun, was disrupted by giant planet migration in the early Solar system. The primordial disc thereby became the source region of objects in the present-day Kuiper belt, scattered disc, and Oort Cloud. I present the thermophysical code ‘Numerical Icy Minor Body evolUtion Simulator’, or nimbus, and use it to study the thermophysical evolution of planetesimals in the primordial disc prior to its disruption. Such modelling is mandatory in order to understand the behaviour of dynamically new comets from the Oort Cloud, as well as the activity of Centaurs and short-period comets from the scattered disc, that return pre-processed to the vicinity of the Sun. I find that bodies in the midst of the primordial disc with diameters ranging 4–$200\, \mathrm{km}$ lost all their CO ice on time-scales of order 0.1–$10\, \mathrm{Myr}$ depending on size, through a combination of protosolar and long-lived radionuclide heating. CO and other hypervolatiles therefore require a less volatile host for their storage. I consider two possible hosts: amorphous water ice and CO2 ice. Because of the high luminosity of the protosun, some primordial disc bodies may have sustained significant crystallization, CO:CO2 segregation, and CO2 sublimation in the uppermost few tens of metres. I discuss how this may affect coma abundance ratios and distant activity in dynamically new comets.

The Moon at thermal infrared wavelengths: a benchmark for asteroid thermal models

Thermal-infrared measurements of asteroids, satellites, and distant minor bodies are crucial for deriving the objects’ sizes, albedos, and in some cases, also the thermophysical properties of the surface material. Depending on the available measurements and auxiliary data, such as visual light curves, spin and shape information, or direct size measurements from occultations or high-resolution imaging techniques, a range of simple to complex thermal models are applied to achieve specific science goals. However, testing these models is often a difficult process and the uncertainties of the derived parameters are not easy to estimate. Here, we make an attempt to verify a widely accepted thermophysical model (TPM) against unique thermal infrared (IR), full-disk, and well-calibrated measurements of the Moon. The data were obtained by the High-resolution InfraRed Sounder (HIRS) instruments on board a fleet of Earth weather satellites that serendipitously scan the surface of the Moon. We found 22 Moon intrusions, taken in 19 channels between 3.75 μm and 15.0 μm, and over a wide phase angle range from −73.1° (waxing Moon) to +73.8° (waning Moon). These measurements include the entire Moon in a single pixel, seen almost simultaneously in all bands. The HIRS filters are narrow and outside the wavelength regime of the Christiansen feature. The similarity between these Moon data and typical asteroid spectral-IR energy distributions allows us to benchmark the TPM concepts and to point out problematic aspects. The TPM predictions match the HIRS measurements within 5% (10% at the shortest wavelengths below 5 μm) when using the Moon’s known properties (size, shape, spin, albedo, thermal inertia, roughness) in combination with a newly established wavelength-dependent hemispherical emissivity. In the 5–7.5 μm and in the 9.5–11 μm ranges, the global emissivity model deviates considerably from the known lunar sample spectra. Our findings will influence radiometric studies of near-Earth and main-belt asteroids in cases where only short-wavelength data (from e.g., NEOWISE, the warm Spitzer mission, or ground-basedM-band measurements) are available. The new, full-disk IR Moon model will also be used for the calibration of IR instrumentation on interplanetary missions (e.g., for Hayabusa-2) and weather satellites.

True beauty lies within: therapist interview of a client who received acceptance and commitment therapy for body dysmorphic disorder

ABSTRACT Objective Body Dysmorphic Disorder (BDD) is reportedly under diagnosed due to the significant shame that individuals experience in revealing the distress they feel regarding their perceived flaws. Despite this, it has a high prevalence rate and is associated with significantly increased risk of suicidal behaviour compared with other mental health disorders. Current first line treatment recommendations include cognitive behaviour therapy and Serotonin Reuptake Inhibitors (SSRIs) however evidence for this is limited. This paper is a collaboration between a therapist and a client, recounting the therapeutic work they did together, using an Acceptance and Commitment Therapy (ACT) approach to recovery from BDD. Method The client attended a one hour semi-structured interview which was audio recorded and transcribed. The interview included open questions regarding the clients’ history and experience of therapy. Results A compassionate stance and a values-based approach are identified as key processes in targeting the suffering associated with shame. Conclusion The non-expert therapeutic stance underpinning the ACT philosophy effectively contested the clients’ expectations for treatment, instead modelling the acceptance of imperfection and tolerance of uncertainty. KEY POINTS What is already known about this topic (1) Body Dysmorphic Disorder (BDD) is a mental health disorder characterised by preoccupation with non-existent or minor body defects. (2) Body Dysmorphic Disorder (BDD) is reportedly under diagnosed due to the significant shame that individuals experience. (3) Difficulties in early parenting experiences such as parental rejection and coercion have been associated with the development of appearance based rejection sensitivity. What this topic adds (1) From an ACT based conceptualisation the symptoms of BDD are considered avoidance strategies used to protect the self from danger (body shame and rejection). (2) A compassionate stance is a transdiagnostic process that was particularly important in acknowledging and attending to the suffering in this case presentation. (3) The client’s awareness of her own core values rendered the control strategies untenable and supported ongoing recovery.

Review of The Minority Body: A Theory of Disability by Elizabeth Barnes

No abstract available.

Phlogopite-rich and phlogopite-poor kimberlite intrusions within the Du Toitspan kimberlite pipe, South Africa: Petrogenetic relationships and localised source heterogeneity

Samples from three petrographically distinct, intrusive kimberlite bodies and associated kimberlite dykes from the eastern lobe of the Du Toitspan kimberlite pipe, Kimberley, South Africa, have been analysed for their bulk rock major and trace element compositions and their olivine and phlogopite compositions. The two dominant intrusive bodies (D13, D14) are distinguished by the one (D13) being phlogopite-rich and best classified as a macrocrystic hypabyssal phlogopite kimberlite, and the other (D14) being phlogopite-poor and best classified as a macrocrystic hypabyssal monticellite kimberlite. The minor D17 intrusive body is classified as a macrocrystic transitional hypabyssal serpentinized phlogopite kimberlite. The associated kimberlite dykes range texturally from aphanitic to macrocrystic and are classified as calcite kimberlites.The major kimberlite intrusions and their associated dykes show no evidence of crustal contamination and are characterised by broadly overlapping geochemistry except for distinctly higher K2O (> 2 wt%) and Al2O3 (>3 wt%) and flattening HREE patterns (Gd/YbN = 6.5–7.0) in the D13 – phlogopite kimberlite compared to the D14 – monticellite kimberlite and the calcite kimberlite dykes (Gd/YbN = 9.6–12.1). These distinguishing geochemical features of the D13 – phlogopite kimberlite are comparable to typical Group II kimberlites in southern Africa. However, their diagnostic incompatible trace element ratios (for example, Th/Nb, La/Nb, Ce/Pb, and Ba/Nb) are instead comparable to other kimberlite intrusions analysed in this study and to southern African Group I kimberlites in general.Semi-quantitative modelling suggests that these kimberlite intrusions could have derived by low (<1%) degrees of partial melting of a source region that is enriched in LREE (Lan = ~6.1; Ybn ~ 1.47) comparable to metasomatised peridotites from the underlying lithospheric mantle. The composition of the D13 phlogopite kimberlite is consistent with a partial melt of a modally metasomatised source containing a higher proportion of residual clinopyroxene relative to garnet (compared to that giving rise to the D14 monticellite kimberlite and calcite kimberlite dykes), as well as accessory amounts of phlogopite, i.e. a garnet phlogopite peridotite (GPP). The absence of K-anomalies on primitive mantle normalized diagrams for the D13 phlogopite kimberlite requires that phlogopite was not a residual phase during partial melting and was exhausted shortly before or at the moment of melt segregation. The higher Gd/Yb ratios and lower K2O in the D14 monticellite kimberlite and calcite kimberlite dykes can be explained by partial melting of a cryptically metasomatized, phlogopite – free, garnet peridotite (GP) source, containing a higher proportion of garnet relative to clinopyroxene. The low absolute K and strong negative K-anomaly on primitive mantle normalized diagrams for the D14 monticellite kimberlite were inherited from a source region that previously experienced cryptic metasomatism by a differentiated fluid already carrying a negative K-anomaly.

The science enabled by a dedicated solar system space telescope

Whitepaper #232 submitted to the Planetary Science and Astrobiology Decadal Survey 2023-2032. Topics: other planetary bodies: Venus, minor bodies, comets, outer plane[...]; other science themes: Interaction of planetary magnetospheres [...]; ground- and space-based telescopes

On the Capture of Interstellar Objects by Our Solar System

Abstract Motivated by recent visits from interstellar comets, along with continuing discoveries of minor bodies in orbit of the Sun, this paper studies the capture of objects on initially hyperbolic orbits by our solar system. Using an ensemble of ∼500 million numerical experiments, this work generalizes previous treatments by calculating the capture cross section as a function of asymptotic speed. The resulting velocity-dependent cross section can then be convolved with any distribution of relative speeds to determine the capture rate for incoming bodies. This convolution is carried out for the usual Maxwellian distribution, as well as the velocity distribution expected for rocky debris ejected from planetary systems. We also construct an analytic description of the capture process that provides an explanation for the functional form of the capture cross section in both the high- and low-velocity limits.

Evolving resting head tremor in parkinsonism: Clinicopathological study of a case

IntroductionResting limb tremor (RLT) is a well known feature in parkinsonism. There is very little information on resting head tremor (RHT) in parkinsonism, and none in pathologically confirmed cases. The association between RLT and RHT remains uncertain. MethodsA Caucasian male developed upper limb tremor and voice changes at age 70. He was first assessed at our clinic at age 72. At age 73 he developed resting head tremor (RHT) which prevented him from falling asleep. His status was documented in longitudinal follow-up at our clinic. He had a total of 14 clinical evaluations and four videos made over 6 years. Autopsy of the brain and spinal cord was performed. ResultsThe resting head tremor improved on antiparkinsonian drugs and resolved completely after four years. Coincident with RHT remission, the upper limb tremor worsened and interfered with feeding, and his lower limb resting tremor became more pronounced. During his course he developed slow, scanning speech and all the cardinal motor findings of parkinsonism. There was no ophthalmoplegia. Post-mortem neuropathological examination revealed prominent progressive supranuclear palsy (PSP) changes and minor Lewy body pathology. ConclusionThis is the first autopsy confirmed case of parkinsonism with RHT. He had dual pathology. Dissociation between RHT and RLT indicates that the oscillatory brain centers for the two were different in this case.

Envelop of reachable asteroids by M-ARGO CubeSat

The Miniaturised Asteroid Remote Geophysical Observer (M-ARGO) is planned to be the first standalone deep-space CubeSat mission to rendezvous with and characterise a near-Earth asteroid. To this aim, it is essential to assess the attainable set of target asteroids. This work presents the initial results of the mission analysis and design of M-ARGO. In particular, the original procedure developed to extract the reachable near-Earth asteroids and the subsequent down-selection process are shown. Hundreds of both time- and fuel-optimal low-thrust trajectory optimisation problems have been solved with an indirect approach, targeting asteroids pre-filtered from the Minor Planet Center Database. The method implements a realistic thruster model, featuring variable input power, thrust, and specific impulse, together with an accurate switching detection technique and analytic derivatives. The analysis shows that approximately 150 minor bodies are found potentially reachable by M-ARGO when departing from the Sun–Earth Lagrange point L2 within a 3-year transfer duration. A manual inspection of the transfer features led to a subset of 41 targets seeming more promising according to mission technological requirements and constraints. Initial results indicate mission feasibility for M-ARGO, which has the potential to enable a completely new class of low-cost deep-space exploration missions.