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we have used the latest available shape model for gas and dust simulations of the inner coma of comet 67p/churyumov-gerasimenko for the period around may 2015 (equinox). we compare results from a purely insolation-driven model with a complementary set of observations made by rosina, virtis, miro, and osiris within the ... | a comparison of multiple rosetta data sets and 3d model calculations of 67p/churyumov-gerasimenko coma around equinox (may 2015) |
cometary activity is a manifestation of sublimation-driven processes at the surface of nuclei. however, cometary outbursts may arise from other processes that are not necessarily driven by volatiles. in order to fully understand nuclear surfaces and their evolution, we must identify the causes of cometary outbursts. in... | six outbursts of comet 46p/wirtanen |
measurements from the rosetta mission have shown a multitude of nonthermal electron distributions in the cometary environment, challenging the previously assumed plasma interaction mechanisms near a cometary nucleus. in this paper, we discuss electron trapping near a weakly outgassing comet from a fully kinetic (partic... | electron trapping in the coma of a weakly outgassing comet |
we have detected h2o and o2 absorption against the far-uv continuum of stars located on lines of sight near the nucleus of comet 67p/churyumov-gerasimenko using the alice imaging spectrograph on rosetta. these stellar appulses occurred at impact parameters of ρ = 4-20 km, and heliocentric distances ranging from rh = - ... | h2o and o2 absorption in the coma of comet 67p/churyumov-gerasimenko measured by the alice far-ultraviolet spectrograph on rosetta |
a cycle in the range of 26-30 myr has been reported in mass extinctions, and terrestrial impact cratering may exhibit a similar cycle of 31 ± 5 myr. these cycles have been attributed to the sun's vertical oscillations through the galactic disc, estimated to take from ∼30 to 42 myr between galactic plane crossings. near... | disc dark matter in the galaxy and potential cycles of extraterrestrial impacts, mass extinctions and geological events |
comet is an experiment at j-parc, japan, which will search for neutrinoless conversion of muons into electrons in the field of a nucleus (μ- + n → e- + n); a lepton flavor violating process. the experimental sensitivity goal for this process is order of 10^-15 for phase-i and 10^-17 for phase-ii experiment, which is a ... | comet muon conversion experiment in j-parc |
aims: cometary ions are constantly produced in the coma, and once produced they are accelerated and eventually escape the coma. we describe and interpret the dynamics of the cometary ion flow, of an intermediate active comet, very close to the nucleus and in the terminator plane.methods: we analysed in situ ion and mag... | cometary ion dynamics observed in the close vicinity of comet 67p/churyumov-gerasimenko during the intermediate activity period |
using boltzmann–vlasov kinetic model, a currentless ion acoustic instability driven by stream of solar wind plasma is studied in a non‑thermal distributed electrons and ions. the non‑thermal distribution considered here is the generalized distribution which has low energetic flat‑top and velocity power law tail at high... | solar wind driven electrostatic instabilities with generalized (r , q ) distribution function |
gravitating systems surrounded by a dynamic sea of substructures experience fluctuations of the local tidal field which inject kinetic energy into the internal motions. this paper uses stochastic calculus techniques to describe `tidal heating' as a random walk of orbital velocities that leads to diffusion in a four-dim... | stochastic tidal heating by random interactions with extended substructures |
context. the mirror tracking system of the canadian automated meteor observatory (camo) can track meteors in real time, providing an effective angular resolution of 1 arc second and a temporal resolution of 100 frames per second. aims. we describe the upgraded hardware and give details of the data calibration and reduc... | high precision meteor observations with the canadian automated meteor observatory: data reduction pipeline and application to meteoroid mechanical strength measurements |
the distinctive cometary x-ray morphology of the recently discovered massive galaxy cluster "el gordo" (act-ct j0102-4915 z = 0.87) indicates that an unusually high-speed collision is ongoing between two massive galaxy clusters. a bright x-ray "bullet" leads a "twin-tailed" wake, with the sunyaev-zel'dovich (sz) centro... | a hydrodynamical solution for the "twin-tailed" colliding galaxy cluster "el gordo" |
we present herschel space observatory pacs spectra of t tauri stars, in which we detect amorphous and crystalline water ice features. using irradiated accretion disk models, we determine the disk structure and ice abundance in each of the systems. combining a model-independent comparison of the ice feature strength and... | detections of trans-neptunian ice in protoplanetary disks |
the origin of the heavily fractionated reservoir of nitrogen in comets remains an issue in the theory of their formation and hence of the solar system. whether the fractionated reservoir traced by comets is inherited from the interstellar cloud or is the product of processes taking place in the protostar, or in the pro... | the nitrogen isotopic ratio of hc3n towards the l1544 prestellar core |
we investigated six bright swirls associated with magnetic anomalies of variable strength using chandrayaan-1 moon mineralogy mapper (m3) hyperspectral image data. we examined the 3 μm absorption band generally ascribed to solar wind-induced oh/h2o and spectral trends in the near-infrared wavelength range at on-swirl a... | processes governing the vis/nir spectral reflectance behavior of lunar swirls |
this paper presents results from our molecular characterization of comet 21p/giacobini-zinner during its 2018 apparition. we followed the comet during four observing runs, for a total of eight nights. the high-resolution spectra of 21p were acquired using ishell—the near-infrared high-resolution immersion echelle spect... | quantifying the evolution of molecular production rates of comet 21p/giacobini-zinner with ishell/nasa-irtf |
abundant mining and industrial activities located in the upper silesian coal basin (uscb) lead to large emissions of the potent greenhouse gas (ghg) methane (ch4). the strong localization of ch4 emitters (mostly confined to known coal mine ventilation shafts) and the large emissions of 448 and 720 kt ch4 yr−1 reported ... | estimating upper silesian coal mine methane emissions from airborne in situ observations and dispersion modeling |
the imprudent use of insecticides causes the development of resistance in insect pest populations, contamination of the environment, biological imbalance and human intoxication. the use of microbial pathogens combined with insecticides has been proposed as an alternative strategy for insect pest management. this ipm ap... | synergistic and additive interactions of shewanella sp., pseudomonas sp. and thauera sp. with chlorantraniliprole and emamectin benzoate for controlling spodoptera litura (fabricius) |
in 2020, during the covid-19 pandemic, containment measures were applied inducing potential changes in air pollutant concentrations and thus in air toxicity. this study evaluates the role of restrictions on biological effects of particulate matter (pm) in different northwest italy sites: urban background, urban traffic... | biological effects of particulate matter samples during the covid-19 pandemic: a comparison with the pre-lockdown period in northwest italy |
centaur 29p/schwassmann-wachmann 1 (sw1) is a highly active object orbiting in the transitional "gateway" region between the centaur and jupiter-family comet (jfc) regions. sw1 is unique among the centaurs in that it experiences quasi-regular major outbursts and produces co emission continuously; however, the source of... | 29p/schwassmann-wachmann 1: a rosetta stone for amorphous water ice and co ↔ co2 conversion in centaurs and comets? |
the interstellar objects 1i/`oumuamua and 2i/borisov confirm the long-held expectation that bodies from one stellar system will be carried to another, allowing, in principle, interstellar panspermia. life might be transferred between stellar systems, depending on the nature of the bodies and how they escaped their syst... | some pertinent issues for interstellar panspermia raised after the discovery of 1i/`oumuamua |
the paper presents experimental studies on the degassing of porous ice and porous mixtures of ice and sand in a vacuum. the study aims to find the relationship between the surface recession rate and the subsurface temperature gradient as well as the granulation and composition of the material. we propose an empirical e... | outgassing of selected possible cometary analogs: laboratory simulations |
having a nucleus darker than charcoal, comets are usually detected from earth through the emissions from their coma. the coma is an envelope of gas that forms through the sublimation of ices from the nucleus as the comet gets closer to the sun. in the far-ultraviolet portion of the spectrum, observations of comae have ... | far-ultraviolet aurora identified at comet 67p/churyumov-gerasimenko |
some scenarios for planetesimal formation go through a phase of collapse of gravitationally bound clouds of millimeter- to centimeter-size pebbles. such clouds can form, for example, through the streaming instability in protoplanetary disks. we model the collapse process with a statistical model to obtain the internal ... | the role of pebble fragmentation in planetesimal formation. ii. numerical simulations |
we present laboratory measurements of the phase functions and degree of linear polarization (dlp) curves of a selection of millimeter-sized cosmic dust analog particles. the set includes particles with similar sizes but diverse internal structure (compact and porous) and absorbing properties. the measured phase functio... | experimental phase function and degree of linear polarization curves of millimeter-sized cosmic dust analogs |
the excessive use of metaldehyde in agriculture to combat mollusks endangers both the environment and non-target organisms. the aim of this study is to investigate the toxicity caused by metaldehyde in alliumcepa with the help of physiological, cytogenetic, biochemical and anatomical parameters. also, dna fragmentation... | assessing the combined toxic effects of metaldehyde mollucide |
chemical reactions and desorption processes are being triggered by incoming ionizing radiation over astrophysical ices in cold space environments. the quantification of these processes is crucial to achieve a detailed understanding of the underlying chemistry occurring within the ice. with this goal, we have upgraded t... | mapping the evolution of pure co2 ices irradiated by ions, uv, and electrons using the upgraded procoda code (employing an effective rate constant ordering by thermochemistry data) |
we analyze 2-5 μm spectroscopic observations of the dust coma of comet 67p/churyumov-gerasimenko obtained with the visible infrared thermal imaging spectrometer (virtis-h) instrument on board rosetta from 3 june to 29 october 2015 at heliocentric distances rh = 1.24-1.55 au. the 2-2.5 μm color, bolometric albedo, and c... | virtis-h observations of the dust coma of comet 67p/churyumov-gerasimenko: spectral properties and color temperature variability with phase and elevation |
detailed morphological and photometric characterisation of comet 29p in the optical region is presented comprising: (a) multi-filter observations of the outburst coma in 2010-2012 with the 2.0-m faulkes telescopes (ft); (b) high-cadence, high-precision photometry in may-september 2014; and (c) hst observations in march... | anatomy of outbursts and quiescent activity of comet 29p/schwassmann-wachmann |
merging galaxy clusters with radio relics provide rare insights to the merger dynamics as the relics are created by the violent merger process. we demonstrate one of the first uses of the properties of the radio relic to reduce the uncertainties of the dynamical variables and determine the three-dimensional (3d) config... | the return of the merging galaxy subclusters of el gordo? |
we have utilized the nasa/irtf 3 m spex instrument’s high-resolution spectral mode to observe and characterize the near-infrared flux emanating from the unusual kepler light curve system kic 8462852. by comparing the resulting 0.8-4.2 μm spectrum to a mesh of model photospheric spectra, the 6 emission line analyses of ... | irtf/spex observations of the unusual kepler light curve system kic8462852 |
combining dynamical models of dust from jupiter-family comets and halley-type comets, we demonstrate that the seasonal variation of the dust/meteoroid environment at mercury is responsible for producing the dawn-dusk asymmetry in mercury’s exosphere observed by the messenger spacecraft. our latest models, calibrated re... | reconciling the dawn-dusk asymmetry in mercury’s exosphere with the micrometeoroid impact directionality |
the localized delivery of new long-lived species to jupiter's stratosphere by comet shoemaker-levy 9 in 1994 opened a window to constrain jovian chemistry and dynamics by monitoring the evolution of their vertical and horizontal distributions. however, the spatial distributions of co and hcn, two of these long-lived sp... | evidence for auroral influence on jupiter's nitrogen and oxygen chemistry revealed by alma |
in august 2019, a second interstellar object 2i/borisov was discovered 2 years after the discovery of the first known interstellar object, 1i/'oumuamua. can we send a spacecraft to this object, using existing technologies? in this paper we assess the technical feasibility of a near-term mission to 2i/borisov. we apply ... | sending a spacecraft to interstellar comet 2i/borisov |
in this chapter, we provide a review of radiative processes in cometary atmospheres spanning a broad range of wavelengths, from radio to x-rays. we focus on spectral modeling, observational opportunities, and anticipated challenges in the interpretation of new observations, based on our current understanding of the ato... | radiative processes as diagnostics of cometary atmospheres |
we carry out a population study of magnetized radio filaments in the galactic centre using meerkat data by focusing on the spacing between the filaments that are grouped. the morphology of a sample of 43 groupings containing 174 magnetized radio filaments are presented. many grouped filaments show harp-like, fragmented... | statistical properties of the population of the galactic centre filaments - ii. the spacing between filaments |
we analyzed the bvr photometry of comet c/2012 j1 (catalina) taken between march 2013 and may 2014 with telescopes ranging from 0.20 to 2.0 m aperture in australia, europe, and the united states. we found an absolute magnitude in the r‑band of h0 = 7.2 ± 0.1 measured with a photometric aperture radius ρ of 42.4 arcsec,... | photometric bvr observations of comet c/2012 j1 (catalina) before and after perihelion |
context. comet 46p/wirtanen is a near-earth object (neo) for which no associated meteor shower has ever been reported.aims: this study is aimed at improving our understanding of why there has been no observed shower activity for this neo to date, as well as to consider whether any past activity could be uncovered from ... | a new meteor shower from comet 46p/wirtanen expected in december 2023 |
the proposed cosmic-induced conflagration of the black mat (bm), at the end of the allerød interstade, dated to the 12.8 ka—younger dryas boundary (ydb), has been variably related to multiple airburst events following earth's encounter with the encke comet. evidence for the bm, as on mt. viso in the western alps of eur... | the younger dryas boundary (ydb): terrestrial, cosmic, or both? |
context. during its two-year mission at comet 67p, rosetta nearly continuously monitored the inner coma plasma environment for gas production rates varying over three orders of magnitude, at distances to the nucleus ranging from a few to a few hundred kilometres. to achieve the best possible measurements, cross-calibra... | plasma densities, flow, and solar euv flux at comet 67p. a cross-calibration approach |
the retrieval of turbulence parameters with profiling doppler wind lidars (dwls) is of high interest for boundary layer meteorology and its applications. dwls provide wind measurements above the level of meteorological masts while being easier and less expensive to deploy. velocity-azimuth display (vad) scans can be us... | towards improved turbulence estimation with doppler wind lidar velocity-azimuth display (vad) scans |
cometary nuclei are considered to most closely reflect the composition of the building blocks of our solar system. as such, comets carry important information about the prevalent conditions in the solar nebula before and after planet formation. recent measurements of the time variation of major and minor volatile speci... | the presence of clathrates in comet 67p/churyumov-gerasimenko |
the intensive measurement campaign comet 1.0 (carbon dioxide and methane mission) took place during may and june 2018, with a focus on greenhouse gases over europe. comet 1.0 aimed at characterising the distribution of ch4 and co2 over significant regional sources with the use of a fleet of research aircraft as well as... | in situ observations of greenhouse gases over europe during the comet 1.0 campaign aboard the halo aircraft |
we compute partial photoionization frequencies of h2o, co2, and co, the major molecules in the coma of comet 67p/churyumov-gerasimenko, the target comet of the ongoing esa rosetta mission. values are computed from thermosphere ionosphere mesosphere energy and dynamics/solar euv experiment solar euv spectra for 2014 aug... | on the electron-to-neutral number density ratio in the coma of comet 67p/churyumov-gerasimenko: guiding expression and sources for deviations |
titan's thick n2-ch4 atmosphere is unlike any in the solar system, and its origin has been shrouded in mystery for over half a century. here, i perform a detailed analysis of chemical and isotopic data from the cassini-huygens mission to develop the hypothesis that titan's (non-photochemical) atmospheric gases came fro... | noble gases, nitrogen, and methane from the deep interior to the atmosphere of titan |
we interpret recent observations of the secondary dust ejecta cloud around the moon from the lunar dust experiment (ldex) on board the nasa lunar atmosphere and dust environment explorer (ladee) spacecraft with help from dynamical models of meteoroids. results suggest that in order to match the spatial structure of obs... | constraining the ratio of micrometeoroids from short- and long-period comets at 1 au from ladee observations of the lunar dust cloud |
context. detection of molecular oxygen and prediction of its abundance have long been a challenge for astronomers. the low abundances observed in few interstellar sources are well above the predictions of current astrochemical models. during the rosetta mission, an unexpectedly high abundance of o2 was discovered in th... | production of o2 through dismutation of h2o2 during water ice desorption: a key to understanding comet o2 abundances |
comet 103p/hartley 2 has diurnally controlled, co2-driven activity on the tip of the small lobe of its bilobate nucleus. such activity is unique among the comet nuclei visited by spacecraft, and suggests that co2 ice is very near the surface, which is inconsistent with our expectations of an object that thermophysicall... | rotationally induced surface slope-instabilities and the activation of co2 activity on comet 103p/hartley 2 |
we present analysis of high spectral resolution nir spectra of co and h2o in comet c/2009 p1 (garradd) taken during its 2011-2012 apparition with the cshell instrument on nasa's infrared telescope facility (irtf). we also present analysis of observations of atomic oxygen in comet garradd obtained with the arces echelle... | evolution of h2o, co, and co2 production in comet c/2009 p1 garradd during the 2011-2012 apparition |
we report on initial results from 20 days’ worth of transiting exoplanet survey satellite spacecraft observations of comet 46p/wirtanen. the long-duration, high-cadence measurements show a 2018 september 26 outburst that exhibited a two-phase, 0.5 mag brightening profile, and may be the best temporally characterized na... | first results from tess observations of comet 46p/wirtanen |
ice sintering is a form of metamorphism that drives the microstructural evolution of an aggregate of grains through surface and volume diffusion. this leads to an increase in the grain-to-grain contact area (neck) and density of the aggregate over time, resulting in the evolution of its strength, porosity, thermal cond... | the microstructural evolution of water ice in the solar system through sintering |
measurements of the nitrogen isotopic ratio in solar system comets show a constant value, ≈140, which is three times lower than the protosolar ratio, a highly significant difference that remains unexplained. observations of static starless cores at early stages of collapse confirm the theoretical expectation that nitro... | depletion and fractionation of nitrogen in collapsing cores |
magnetic fields inconsistent with draped interplanetary magnetic fields and crustal fields have been observed on mars. considering the discovery of a global looping magnetic field around the venusian magnetotail and the similarities in the solar wind interactions between mars and venus, we use mars atmosphere and volat... | the induced global looping magnetic field on mars |
dunes, dune fields, and ripples are unique and useful records of the interaction between wind and granular materials - finding such features on a planetary surface immediately suggests certain information about climate and surface conditions (at least during the dunes' formation and evolution). additionally, studies of... | our evolving understanding of aeolian bedforms, based on observation of dunes on different worlds |
a severe reduction of greenhouse gas emissions is necessary to reach the objectives of the paris agreement. the implementation and continuous evaluation of mitigation measures requires regular independent information on emissions of the two main anthropogenic greenhouse gases, carbon dioxide (co2) and methane (ch4). ou... | estimating ch4, co2 and co emissions from coal mining and industrial activities in the upper silesian coal basin using an aircraft-based mass balance approach |
we present an extensive data set of ground-based observations and models of the dust environment of comet 67p/churyumov-gerasimenko covering a large portion of the orbital arc from about 4.5 au pre-perihelion through 3.0 au post-perihelion, acquired during the current orbit. in addition, we have also applied the model ... | the dust environment of comet 67p/churyumov-gerasimenko: results from monte carlo dust tail modelling applied to a large ground-based observation data set |
we present a detailed study of the cometary ionospheric response to a cometary brightness outburst using in situ measurements for the first time. the comet 67p/churyumov-gerasimenko (67p) at a heliocentric distance of 2.4 au from the sun, exhibited an outburst at ~1000 ut on 19 february 2016, characterized by an increa... | impact of a cometary outburst on its ionosphere. rosetta plasma consortium observations of the outburst exhibited by comet 67p/churyumov-gerasimenko on 19 february 2016 |
as rosetta was orbiting comet 67p/churyumov-gerasimenko, the ion and electron sensor detected negative particles with angular distributions like those of the concurrently measured solar wind protons but with fluxes of only about 10% of the proton fluxes and energies of about 90% of the proton energies. using well-known... | charge exchange in cometary coma: discovery of h- ions in the solar wind close to comet 67p/churyumov-gerasimenko |
according to current theories of the formation of stellar systems, comets belong to the oldest and most pristine class of bodies to be found around a star. when approaching the sun, the nucleus shows increasing activity and a pressure increase inside the material causes sublimated and trapped gas molecules to stream aw... | viscous and knudsen gas flow through dry porous cometary analogue material |
a detailed exploration of the potential energy surface of quinoline cation (c9h7n·+) is carried out to extend the present understanding of its fragmentation mechanisms. density functional theory calculations have been performed to explore new fragmentation schemes, giving special attention to previously unexplored path... | photodissociation of quinoline cation: mapping the potential energy surface |
since their formation in the protosolar nebula some ∼4.5 billion years ago, comets are in storage in cold distant regions of the solar system, the kuiper belt/scattered disk or oort cloud. therefore, they have been considered as mostly unaltered samples of the protosolar nebula. however, a significant dose of energy is... | the effect of cosmic rays on cometary nuclei. ii. impact on ice composition and structure |
context. formamide (nh2hco) and isocyanic acid (hnco) have been observed as gaseous species in several astronomical environments such as cometary comae and pre- and proto-stellar objects. a debate is open on the formation route of those molecules, in particular if they are formed by chemical reactions in the gas phase ... | synthesis of formamide and isocyanic acid after ion irradiation of frozen gas mixtures |
one of the scientific objectives of the rosetta mission is to investigate the diamagnetic cavity of comet 67p/churyumov-gerasimenko. we employed combined data of several instruments of the rosetta plasma consortium to identify and study diamagnetic cavity crossing events. using electron data from the ion electron senso... | charged particle signatures of the diamagnetic cavity of comet 67p/churyumov-gerasimenko |
aims: we use four observational data sets, mainly from the rosetta mission, to constrain the activity pattern of the nucleus of comet 67p/churyumov-gerasimenko (67p).methods: we developed a numerical model that computes the production rate and non-gravitational acceleration of the nucleus of comet 67p as a function of ... | constraining models of activity on comet 67p/churyumov-gerasimenko with rosetta trajectory, rotation, and water production measurements |
"the supernova of 1604 marks a major turning point in the cosmological crisis of the sixteenth and seventeenth centuries. capturing the eyes and imagination of europe, it ignited an explosion of ideas that forever changed the face of science. variously interpreted as a comet or star, the new luminary brought together a... | kepler's new star (1604): context and controversy |
hcn is a commonly observed molecule in solar system bodies and in interstellar environments. its abundance with respect to cn is a proposed tracer of uv exposure. hcn is also frequently used to probe the thermal history of objects, by measuring its degree of nitrogen fractionation. to address the utility of hcn as a pr... | cyanide photochemistry and nitrogen fractionation in the mwc 480 disk |
imidacloprid (imid), a systemic neonicotinoid insecticide, is broadly used worldwide. it is reported to contaminate aquatic systems. this study was proposed to evaluate oxidative stress and genotoxicity of imid on nile tilapia (oreochromis niloticus) and the protective effect of ascorbic acid (asc). o. niloticus juveni... | the role of ascorbic acid combined exposure on imidacloprid-induced oxidative stress and genotoxicity in nile tilapia |
this study provides the first observations of plutogenic ions and their unique interaction with the solar wind. we find ~20% solar wind slowing that maps to a point only ~4.5 rp upstream of pluto and a bow shock most likely produced by comet-like mass loading. the pluto obstacle is a region of dense heavy ions bounded ... | pluto's interaction with the solar wind |
we simulate the stresses induced by temperature changes in a putative hard layer near the surface of comet 67p/churyumov-gerasimenko with a thermo-viscoelastic model. such a layer could be formed by the recondensation or sintering of water ice (and dust grains), as suggested by laboratory experiments and computer simul... | thermal fracturing on comets. applications to 67p/churyumov-gerasimenko |
context. because comets are part of the most primitive bodies of our solar system, establishing their chemical composition and comparing them to other astrophysical bodies gives new constraints on the formation and evolution of organic matter throughout the solar system. for two years, the time-of-flight secondary ion ... | h/c elemental ratio of the refractory organic matter in cometary particles of 67p/churyumov-gerasimenko |
aims: we provide a measurement of the seasonal evolution of the dust deposit erosion and accretion in the hapi region of comet 67p/churyumov-gerasimenko with a vertical accuracy of 0.2-0.9 m.methods: we used osiris narrow angle camera images with a spatial scale of lower than 1.30 m px-1 and developed a tool to monitor... | time evolution of dust deposits in the hapi region of comet 67p/churyumov-gerasimenko |
context. the landing and rebound of the philae lander, which was part of the esa rosetta mission, enabled us to study the mechanical properties of the surface of comet 67p/churyumov-gerasimenko, because we could use philae as an impact probe.aims: the aim is to approximate the descent and rebound trajectory of the phil... | compressive strength of comet 67p/churyumov-gerasimenko derived from philae surface contacts |
recent models find that nuclei of comets are a mixture of water-rich and water-poor cm-sized pebbles. we aim to fit the correlation of the deuterium-to-hydrogen ratio, d/h, with the nucleus active area fraction. pebble parameters, constrained by the rosetta mission data, depend on where pebbles accreted in the protopla... | water and deuterium-to-hydrogen ratio in comets |
aims: the tensile strength of granular matter is of great importance to our understanding of the evolution of comets and to our attempts to reproduce processes on cometary surfaces in laboratory experiments. in this work, we investigate the tensile strength of three different materials and their mixtures, which can be ... | tensile strength of dust-ice mixtures and their relevance as cometary analog material |
remote sensing observations of dust particles ejected from comets provide important hints on the intimate nature of the materials composing these primitive objects. the measurement of dust coma backscattering ratio, bsr, defined as the ratio of the reflectance at phase angle 0° and 30°, helps tuning theoretical models ... | the backscattering ratio of comet 67p/churyumov-gerasimenko dust coma as seen by osiris onboard rosetta |
the rosetta orbiter spectrometer for ion and neutral analysis (rosina) instrument onboard the rosetta spacecraft has measured molecular oxygen (o2) in the coma of comet 67p/churyumov-gerasimenko (67p/c-g) in surprisingly high abundances. these measurements mark the first unequivocal detection of o2 in a cometary enviro... | origin of molecular oxygen in comets: current knowledge and perspectives |
ex lup is the prototype of a class of pre-main-sequence eruptive stars defined by their repetitive outbursts lasting several months. in 2008 january-september ex lup underwent its historically largest outburst, brightening by about 4 mag in visual light. in previous studies we discovered ongoing silicate crystal format... | spectral evolution and radial dust transport in the prototype young eruptive system ex lup |
we present observations from the rosetta plasma consortium of the effects of stormy solar wind on comet 67p/churyumov-gerasimenko. four corotating interaction regions (cirs), where the first event has possibly merged with a coronal mass ejection, are traced from earth via mars (using mars express and mars atmosphere an... | solar wind interaction with comet 67p: impacts of corotating interaction regions |
the solar system's oort cloud can be perturbed by the galactic tide and by individual passing stars. these perturbations can inject oort cloud objects into the inner parts of the solar system, where they may be observed as the long-period comets (periods longer than 200 yr). using dynamical simulations of the oort clou... | finding the imprints of stellar encounters in long-period comets |
context. mainly for historical reasons, nearly all of the current thermophysical models of dust activity rely on the poorly justified assumption of cohesionless dust lifted by a gas drag force against the weak nucleus gravity. the interpretation of rosetta data and our understanding of comet activity is particularly se... | is near-surface ice the driver of dust activity on 67p/churyumov-gerasimenko |
context. first results based on gaia data show that the well-known star gliese 710 will be the closest flyby star in the next several myrs and its minimum distance from the sun will be almost five times smaller than that suggested by pre-gaia solution.aims: the aim of this work is to investigate the proximity parameter... | gliese 710 will pass the sun even closer. close approach parameters recalculated based on the first gaia data release |
context. the n2 and co-rich and water-depleted comet c/2016 r2 (pan-starrs) - hereafter "c/2016 r2" - is a unique comet for detailed spectroscopic analysis.aims: we aim to explore the associated photochemistry of parent species, which produces different metastable states and forbidden emissions, in this cometary coma o... | forbidden atomic carbon, nitrogen, and oxygen emission lines in the water-poor comet c/2016 r2 (pan-starrs) |
we present an analysis of transient events observed by the visible infrared thermal imaging spectrometer, instrument aboard rosetta, for the dates of 2015 august 10, september 13 and 14, during the two months surrounding the comet perihelion passage of the rosetta spacecraft. we detected and characterized events with l... | summer outbursts in the coma of comet 67p/churyumov-gerasimenko as observed by rosetta-virtis |
saturn’s rings are rock-poor, containing 90%-95% ice by mass. as a group, saturn’s moons interior to and including tethys are also about 90% ice. tethys itself contains < 6 % rock by mass, in contrast to its similar-mass outer neighbor dione, which contains > 40 % rock. here we simulate the evolution of a massive... | accretion of saturn’s inner mid-sized moons from a massive primordial ice ring |
the recent discovery of the first confirmed interstellar objects (isos) passing through the solar system on clearly hyperbolic objects opens the potential for near term iso missions, either to the two known objects, or to similar objects found in the future. such isos are the only exobodies we have a chance of accessin... | exobodies in our back yard: science from missions to nearby interstellar objects |
we review the history of spacecraft encounters with comets, concentrating on those that took place in the recent past, since the publication of the comets ii book. this includes the flyby missions stardust and deep impact, and their respective extended missions, the rosetta rendezvous mission, and serendipitous encount... | past and future comet missions |
the coma of comet c/2016 r2 (panstarrs) is one of the most chemically peculiar ever observed, in particular due to its extremely high co/h2o and ${{\rm{n}}}_{2}^{+}$ /h2o ratios, and unusual trace volatile abundances. however, the complex shape of its co emission lines, as well as uncertainties in the coma structure an... | a sublime 3d model for cometary coma emission: the hypervolatile-rich comet c/2016 r2 (panstarrs) |
the disk midplane temperature is potentially affected by the dust traps/rings. the dust depletion beyond the water snowline will cast a shadow. in this study, we adopt a detailed gas-grain chemical reaction network, and investigate the radial gas and ice abundance distributions of dominant carbon-, oxygen-, and nitroge... | the molecular composition of shadowed proto-solar disk midplanes beyond the water snowline |
context. 29p/schwassmann-wachmann 1 is a distant centaur/comet, showing persistent co-driven activity and frequent outbursts.aims: we aim to better characterize its gas and dust activity from multiwavelength observations performed during outbursting and quiescent states.methods: we used the hifi, pacs and spire instrum... | water, hydrogen cyanide, carbon monoxide, and dust production from distant comet 29p/schwassmann-wachmann 1 |
9 years in the saturn system, the cassini spacecraft finally observed titan in the supersonic and super-alfvénic solar wind. these unique observations reveal that titan's interaction with the solar wind is in many ways similar to unmagnetized planets mars and venus and active comets in spite of the differences in the p... | titan's interaction with the supersonic solar wind |
context. a new type of low-frequency wave was detected by the magnetometer of the rosetta plasma consortium at the comet during the initial months after the arrival of the rosetta spacecraft at comet 67p/churyumov-gerasimenko. this large-amplitude, nearly continuous wave activity is observed in the frequency range from... | low-frequency waves at comet 67p/churyumov-gerasimenko. observations compared to numerical simulations |
recent meerkat radio continuum observations of the galactic centre at 20 cm show a large population of non-thermal radio filaments (nrfs) in the inner few hundred pc of the galaxy. we have selected a sample of 57 radio sources, mainly compact objects, in the meerkat mosaic image that appear to be associated with nrfs. ... | the population of galactic centre filaments - iii. candidate radio and stellar sources |
sintering is a process driven by mass transport that leads to the formation of a sinter neck between neighbouring particles. the temporal growth of the neck area can lead to an increase of the mechanical strength and increased heat conductivity of granular icy surfaces on solar system bodies. for water ice, sublimation... | sintering and sublimation of micrometre-sized water-ice particles: the formation of surface crusts on icy solar system bodies |
aims: we calculate the size-frequency distribution of the boulders on the southern hemisphere of comet 67p churyumov-gerasimenko (67p), which was in shadow before the end of april 2015. we compare the new results with those derived from the northern hemisphere and equatorial regions of 67p, highlighting the possible ph... | the southern hemisphere of 67p/churyumov-gerasimenko: analysis of the preperihelion size-frequency distribution of boulders ≥7 m |
we numerically model the dynamics of the enceladus plume ice grains and define our nominal plume model as having a particle size distribution n(r) ~ r-q with q = 4 and a total particulate mass rate of 16 kg s-1. this mass rate is based on average plume brightness observed by cassini across a range of orbital positions.... | collecting amino acids in the enceladus plume |
context. near- and mid-infrared observations have revealed the presence of organic refractory materials in the solar system, in cometary nuclei and on the surface of centaurs, kuiper-belt and trans-neptunian objects. in these astrophysical environments, organic materials can be formed because of the interaction of froz... | irradiation dose affects the composition of organic refractory materials in space. results from laboratory analogues |
context. the swan lyman α photometer onboard soho monitored the hydrogen cloud around comet 67p/churyumov-gerasimenko (67p) postperihelion at the three last perihelions in 1996, 2002, and 2009.aims: combining the swan results with some new rosetta data allows estimating the erosion rate of the comet, quantified by the ... | estimate of the erosion rate from h2o mass-loss measurements from swan/soho in previous perihelions of comet 67p/churyumov-gerasimenko and connection with observed rotation rate variations |
experimental simulations in the laboratory may provide important information about the chemical evolution occurring in various astrophysical objects such as extraterrestrial ices. interstellar or (pre)cometary ice analogues made of h2o, ch3oh, and nh3 at 77 k, when subjected to an energetic process (vuv photons, electr... | insight into the molecular composition of laboratory organic residues produced from interstellar/pre-cometary ice analogues using very high resolution mass spectrometry |
electric field measurements from cometary environments are very rare but can provide important information on how plasma waves help fashion the plasma environment. the long dwelling time of the rosetta spacecraft close to comet 67p/churyumov-gerasimenko promises to improve this state. we here present the first electric... | rosetta measurements of lower hybrid frequency range electric field oscillations in the plasma environment of comet 67p |
saprolegniosis is a worldwide fungal-like infection affecting freshwater fishes and their eggs. reports show high mortalities and subsequent economic losses annually from saprolegnia infections. most therapeutants against saprolegnia spp. infections are inefficient and some have negative impact on the environment. in t... | efficacy and safety of boric acid as a preventive treatment against saprolegnia infection in nile tilapia (oreochromis niloticus) |
this paper is a continuation of miles et al. (2015) [icarus] and miles (2015b) [icarus], which detail new observations of comet 29p/schwassmann−wachmann, characterise its rotational period (∼57 d), and identify the presence of discrete sources of outburst on its nucleus: the latter ruling out amorphous-to-crystalline h... | heat of solution: a new source of thermal energy in the subsurface of cometary nuclei and the gas-exsolution mechanism driving outbursts of comet 29p/schwassmann−wachmann and other comets |
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