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aims: we report on the first major temporal morphological changes observed on the surface of the nucleus of comet 67p/churyumov-gerasimenko in the smooth terrains of the imhotep region.methods: we used images of the osiris cameras onboard rosetta to follow the temporal changes from 24 may 2015 to 11 july 2015.results: ... | temporal morphological changes in the imhotep region of comet 67p/churyumov-gerasimenko |
the rosetta mission shall accompany comet 67p/churyumov-gerasimenko from a heliocentric distance of >3.6 astronomical units through perihelion passage at 1.25 astronomical units, spanning low and maximum activity levels. initially, the solar wind permeates the thin comet atmosphere formed from sublimation, until the... | birth of a comet magnetosphere: a spring of water ions |
context. the cometary secondary ion mass analyzer (cosima) on board rosetta is dedicated to the collection and compositional analysis of the dust particles in the coma of 67p/churyumov-gerasimenko (67p).aims: investigation of the physical properties of the dust particles collected along the comet trajectory around the ... | dust particle flux and size distribution in the coma of 67p/churyumov-gerasimenko measured in situ by the cosima instrument on board rosetta |
the size and velocity distribution of cosmic dust particles entering the earth's atmosphere is uncertain. here we show that the relative concentrations of metal atoms in the upper mesosphere, and the surface accretion rate of cosmic spherules, provide sensitive probes of this distribution. three cosmic dust models are ... | on the size and velocity distribution of cosmic dust particles entering the atmosphere |
we report the detection of the pre-biotic molecule ch3nco in a solar-type protostar, iras16293-2422 b. a significant abundance of this species on the surface of the comet 67p/churyumov-gerasimenko has been proposed, and it has recently been detected in hot cores around high-mass protostars. we observed iras16293-2422 b... | detection of methyl isocyanate (ch3nco) in a solar-type protostar |
comets in the oort cloud evolve under the influence of internal and external perturbations, such as giant planets, stellar passages, and the galactic gravitational tidal field. we aim to study the dynamical evolution of the comets in the oort cloud, accounting for the perturbation of the galactic tidal field and passin... | galactic tide and local stellar perturbations on the oort cloud: creation of interstellar comets |
we investigate the delivery of regular and deuterated forms of water from prestellar cores to circumstellar disks. we adopt a semi-analytical, axisymmetric, two-dimensional collapsing core model with post-processing gas-ice astrochemical simulations, in which a layered ice structure is considered. the physical and chem... | water delivery from cores to disks: deuteration as a probe of the prestellar inheritance of h2o |
context. our galaxy is composed of different stellar populations with varying chemical abundances, which are thought to imprint the composition of planet building blocks (pbbs). as such, the properties of stars should affect the properties of planets and small bodies formed in their systems. in this context, high-resol... | how the origin of stars in the galaxy impacts the composition of planetary building blocks |
in-situ study of comet 1p/halley during its 1986 apparition revealed a surprising abundance of organic coma species. it remained unclear, whether or not these species originated from polymeric matter. now, high-resolution mass-spectrometric data collected at comet 67p/churyumov-gerasimenko by esa's rosetta mission unve... | identification and characterization of a new ensemble of cometary organic molecules |
the effect of dust ion collisional frequency on dust ion acoustic waves (diaws) is investigated in a magnetized collisional dusty plasma with isothermal electrons considering an external periodic perturbation. employing the reductive perturbation technique, the damped kadomtsev-petviashili equation is derived to descri... | effect of dust ion collisional frequency on transition of dust ion acoustic waves from quasiperiodic motion to limit cycle oscillation in a magnetized dusty plasma |
we identify a sample of 27 long-period comets for which both nongravitational accelerations and lyα-based gas production rates are available. seven of the 27 comets (i.e., ~25%) did not survive perihelion because of nucleus fragmentation or complete disintegration. empirically, the latter nuclei have the smallest gas p... | destruction of long-period comets |
recently, a rapid increase in radiocarbon (14c) was observed in japanese tree rings at ad 774/775. various explanations for the anomaly have been offered, such as a supernova, a γ-ray burst, a cometary impact, or an exceptionally large solar particle event (spe). however, evidence of the origin and exact timing of the ... | solar superstorm of ad 774 recorded subannually by arctic tree rings |
the osiris (optical, spectroscopic and infrared remote imaging system) instrument on board the esa rosetta spacecraft collected data of 67p/churyumov-gerasimenko for over 2 yr. osiris consists of two cameras, a narrow angle camera and a wide angle camera. for specific imaging sequences related to the observation of dus... | dust mass distribution around comet 67p/churyumov-gerasimenko determined via parallax measurements using rosetta's osiris cameras |
we present observations of decimetre-sized, likely ice-containing aggregates ejected from a confined region on the surface of comet 67p/churyumov-gerasimenko. the images were obtained with the narrow angle camera of the optical, spectroscopic, and infrared remote imaging system on board the rosetta spacecraft in 2016 j... | acceleration of individual, decimetre-sized aggregates in the lower coma of comet 67p/churyumov-gerasimenko |
we present a photometric detection of the first brightness dips of the unique variable star kic 8462852 since the end of the kepler space mission in 2013 may. our regular photometric surveillance started in 2015 october, and a sequence of dipping began in 2017 may continuing on through the end of 2017, when the star wa... | the first post-kepler brightness dips of kic 8462852 |
a consensus view on the formation of planetesimals is now exposed to a threat, since recent numerical studies on the mechanical properties of dust aggregates tend to dispute the conceptual picture that submicrometer-sized grains conglomerate into planetesimals in protoplanetary discs. with the advent of precise laborat... | the tensile strength of dust aggregates consisting of small elastic grains: constraints on the size of condensates in protoplanetary discs |
this paper considers the dynamics of the scattering of planetesimals or planetary embryos by a planet on a circumstellar orbit. we classify six regions in the planet's mass versus semimajor axis parameter space according to the dominant outcome for scattered objects: ejected, accreted, remaining, escaping, oort cloud, ... | how to design a planetary system for different scattering outcomes: giant impact sweet spot, maximizing exocomets, scattered discs |
molecular oxygen has been detected in the coma of comet 67p/churyumov-gerasimenko with abundances in the 1%-10% range by the rosetta orbiter spectrometer for ion and neutral analysis-double focusing mass spectrometer instrument on board the rosetta spacecraft. here we find that the radiolysis of icy grains in low-densi... | origin of molecular oxygen in comet 67p/churyumov-gerasimenko |
nitrogen fractionation is commonly used to assess the thermal history of solar system volatiles. with alma it is for the first time possible to directly measure {}14{{n}}/{}15{{n}} ratios in common molecules during the assembly of planetary systems. we present alma observations of the {{{h}}}13{cn} and {{hc}}15{{n}} j=... | nitrogen fractionation in protoplanetary disks from the h13cn/hc15n ratio |
context. certain types of supernova remnants (snrs) in our galaxy are assumed to be pevatrons, capable of accelerating cosmic rays (crs) to ~ pev energies. however, conclusive observational evidence for this has not yet been found. the snr g106.3+2.7, detected at 1-100 tev energies by different γ-ray facilities, is one... | magic observations provide compelling evidence of hadronic multi-tev emission from the putative pevatron snr g106.3+2.7 |
the polar regions of the moon and mercury both have permanently shadowed environments, potentially capable of harboring ice (cold traps). while cold traps are likely to have been stable for nearly 4 gyr on mercury, this has not been the case for the moon. roughly 3 ± 1 gya, when the moon is believed to have resided at ... | evolution of lunar polar ice stability |
broadband high reflectance in nature is often the result of randomly, three-dimensionally structured materials. this study explores unique optical properties associated with one-dimensional nanostructures discovered in silk cocoon fibers of the comet moth, argema mittrei. the fibers are populated with a high density of... | nanostructured fibers as a versatile photonic platform: radiative cooling and waveguiding through transverse anderson localization |
the microwave instrument on the rosetta orbiter (miro) has been observing the coma of comet 67p/churyumov-gerasimenko almost continuously since june 2014 at wavelengths near 0.53 mm. we present here a map of the water column density in the inner coma (within 3 km from nucleus center) when the comet was at 3.4 au from t... | distribution of water around the nucleus of comet 67p/churyumov-gerasimenko at 3.4 au from the sun as seen by the miro instrument on rosetta |
methanol is a key species in astrochemistry because it is the most abundant organic molecule in the interstellar medium and is thought to be the mother molecule of many complex organic species. estimating the deuteration of methanol around young protostars is of crucial importance because it highly depends on its forma... | interferometric observations of warm deuterated methanol in the inner regions of low-mass protostars |
we report the first in situ detection of halogens in a cometary coma, that of 67p/churyumov-gerasimenko. neutral gas mass spectra collected by the european space agency's rosetta spacecraft during four periods of interest from the first comet encounter up to perihelion indicate that the main halogen-bearing compounds a... | halogens as tracers of protosolar nebula material in comet 67p/churyumov-gerasimenko |
the 163 comets observed during the wise/neowise prime mission represent the largest infrared survey to date of comets, providing constraints on dust, nucleus size, and co + co2 production. we present detailed analyses of the wise/neowise comet discoveries, and discuss observations of the active comets showing 4.6 μm ba... | the neowise-discovered comet population and the co + co2 production rates |
earth is deficient in carbon and nitrogen by up to ~4 orders of magnitude compared with the sun. destruction of (carbon- and nitrogen-rich) refractory organics in the high-temperature planet-forming regions could explain this deficiency. assuming a refractory cometary composition for these grains, their destruction enh... | evidence for ubiquitous carbon grain destruction in hot protostellar envelopes |
in recent years, phosphorus monoxide (po), an important molecule for prebiotic chemistry, has been detected in star-forming regions and in the comet 67p/churyumov-gerasimenko. these studies have revealed that, in the interstellar medium (ism), po is systematically the most abundant p-bearing species, with abundances th... | formation of phosphorus monoxide (po) in the interstellar medium: insights from quantum-chemical and kinetic calculations |
context. di-deuterated molecules are observed in the earliest stages of star formation at abundances of a few percent relative to their nondeuterated isotopologs, which is unexpected considering the scarcity of deuterium in the interstellar medium. with sensitive observations leading to the detection of a steadily incr... | successive deuteration in low-mass star-forming regions: the case of d2-methanol (chd2oh) in iras 16293-2422 |
a major point of interest in cometary plasma physics has been the diamagnetic cavity, an unmagnetized region in the innermost part of the coma. here we combine langmuir and mutual impedance probe measurements to investigate ion velocities and electron temperatures in the diamagnetic cavity of comet 67p, probed by the r... | ion velocity and electron temperature inside and around the diamagnetic cavity of comet 67p |
context. there is an active debate about whether the properties of comets as observed today are primordial or, alternatively, if they are a result of collisional evolution or other processes.aims: we investigate the effects of collisions on a comet with a structure like 67p/churyumov-gerasimenko (67p). we develop scali... | how primordial is the structure of comet 67p?. combined collisional and dynamical models suggest a late formation |
we have studied the dependence of azimuthal anisotropy v2 for inclusive and identified charged hadrons in au +au and cu +cu collisions on collision energy, species, and centrality. the values of v2 as a function of transverse momentum pt and centrality in au +au collisions at √{s nn}=200 and 62.4 gev are the same withi... | systematic study of azimuthal anisotropy in cu + cu and au + au collisions at √{snn}=62.4 and 200 gev |
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 outgas... | on the spin dynamics of elongated minor bodies with applications to a possible solar system analogue composition for 'oumuamua |
we examine the dispersion of the degree of linear polarization p in comets at phase angle 90° where the maximum amplitude of positive polarization pmax occurs. the range of polarization observed in comets is from 7% up to more than 30%, and this cannot be explained through depolarization by gaseous emissions. instead, ... | the positive-polarization of cometary comae |
nonlinear damped modified gardner equation is derived from the dust hydrodynamic model in dusty plasma, which is collisional, unmagnetized, and has two temperature ions. an extended version of the reductive perturbation technique (rpt) is used to derive the said equations. approximate analytical solitary wave solution ... | variable dust charge generates a special type of nonlinear structures through modified gardner equations |
aims: we provide a detailed morphological analysis of the aswan site on comet 67p/churyumov-gerasimenko (67p). we derive the size-frequency distribution of boulders ≥2 m and correlate this distribution with the gravitational slopes for the first time on a comet. we perform the spectral analysis of this region to unders... | aswan site on comet 67p/churyumov-gerasimenko: morphology, boulder evolution, and spectrophotometry |
several lines of observational evidence suggest that white dwarfs receive small birth kicks due to anisotropic mass-loss. if other stars possess extrasolar analogues to the solar oort cloud, the orbits of comets in such clouds will be scrambled by white dwarf natal kicks. although most comets will be unbound, some will... | evaporation and accretion of extrasolar comets following white dwarf kicks |
the ampte (active magnetospheric particle tracer explorers) mission provided in situ measurements of collisionless momentum and energy exchange between an artificial, photo-ionized barium plasma cloud and the streaming, magnetized hydrogen plasma of the solar wind . one of its most significant findings was the unantici... | collisionless momentum transfer in space and astrophysical explosions |
on 2016 july 03, several instruments onboard esa's rosetta spacecraft detected signs of an outburst event on comet 67p, at a heliocentric distance of 3.32 au from the sun, outbound from perihelion. we here report on the inferred properties of the ejected dust and the surface change at the site of the outburst. the acti... | evidence of sub-surface energy storage in comet 67p from the outburst of 2016 july 03 |
rotating star clusters near supermassive black holes are studied using touma-tremaine thermodynamics of gravitationally interacting orbital ellipses. a simple numerical procedure for calculating thermodynamic equilibrium states for an arbitrary distribution of stars over masses and semimajor axes is described. spontane... | the thermodynamics of rotating black hole star clusters |
we present the results of a molecular survey of comet 46p/wirtanen undertaken with the iram 30-m and noema radio telescopes in december 2018. observations at iram 30-m during the 12-18 december period comprise a 2 mm spectral survey covering 25 ghz and a 1 mm survey covering 62 ghz. the gas outflow velocity and kinetic... | molecular composition of comet 46p/wirtanen from millimetre-wave spectroscopy |
acetaldehyde is of interest to astrochemists for its relevance to both interstellar and cometary chemistry, but little infrared (ir) spectral data have been published for the solid phases of this compound. here we present ir spectra of three forms of solid acetaldehyde, with spectra for one form being published for the... | quantifying acetaldehyde in astronomical ices and laboratory analogues: ir spectra, intensities, 13c shifts, and radiation chemistry |
we review the different scenarios for the origin of light noble gases (he, ne, and ar) on earth. several sources could have contributed to the earth's noble gas budget: implanted solar wind, solar nebula gas, chondrites, and comets. although there is evidence for "solar-like" neon in the earth's mantle, questions remai... | origin of light noble gases (he, ne, and ar) on earth: a review |
aims: 67p/churyumov-gerasimenko is the target comet of the esa's rosetta mission. after commissioning at the end of march 2014, the optical, spectroscopic, and infrared remote imaging system (osiris) onboard rosetta, started imaging the comet and its dust environment to investigate how they change and evolve while appr... | 67p/churyumov-gerasimenko: activity between march and june 2014 as observed from rosetta/osiris |
the anomalously low ortho-to-para ratios (oprs) exhibited by gaseous water in space have been used to determine the formation temperature (<50 kelvin) of ice on cold interstellar dust. this approach assumes that the opr of water desorbed from ice is related to the ice formation temperature on the dust. however, we r... | statistical ortho-to-para ratio of water desorbed from ice at 10 kelvin |
we measured direct photons for pt<5 gev /c in minimum bias and 0%-40% most-central events at midrapidity for cu +cu collisions at √{snn}=200 gev . the e+e- contribution from quasireal direct virtual photons has been determined as an excess over the known hadronic contributions in the e+e- mass distribution. a clear ... | low-momentum direct-photon measurement in cu + cu collisions at √{sn n}=200 gev |
aims: using data from the rosetta mission to comet 67p/churyumov-gerasimenko, we evaluate the physical properties of the surface and subsurface of the nucleus and derive estimates for the thermal inertia (ti) and roughness in several regions on the largest lobe of the nucleus.methods: we have developed a thermal model ... | thermal inertia and roughness of the nucleus of comet 67p/churyumov-gerasimenko from miro and virtis observations |
two basic routes for planetesimal formation have been proposed over the last decades. one is a classical `slow-growth' scenario. another one is particle concentration models, in which small pebbles are concentrated locally and then collapse gravitationally to form planetesimals. both types of models make certain predic... | debris disc constraints on planetesimal formation |
we report on imaging and spectroscopic observations of comet c/2016 r2 (pan-starrs) obtained with the 0.8 m and 2.7 m telescopes of mcdonald observatory in 2017 november and december, respectively. the comet was at a heliocentric distance greater than 3 au during both sets of observations. the images showed a well-deve... | strong co+ and n2+ emission in comet c/2016 r2 (pan-starrs) |
we present the first high-resolution, submillimeter-wavelength polarimetric observations of—and thus direct observations of the magnetic field morphology within—the dense gas of the pillars of creation in m16. these 850 μm observations, taken as part of the b-fields in star-forming region observations survey (bistro) u... | first observations of the magnetic field inside the pillars of creation: results from the bistro survey |
context. dust deposits or dust cover are a prevalent morphology in the northern hemi-nucleus of comet 67p/churyumov-gerasimenko (67p). the evolution of the dust deposits was captured by the osiris camera system onboard the rosetta spacecraft having escorted the comet for over two years. the observations shed light on t... | seasonal erosion and restoration of the dust cover on comet 67p/churyumov-gerasimenko as observed by osiris onboard rosetta |
the complete sample of large-perihelion nearly-parabolic comets discovered during the period 1901-2010 is studied, starting with their orbit determination. next, an orbital evolution that includes three perihelion passages (previous-observed-next) is investigated in which a full model of galactic perturbations and pert... | oort spike comets with large perihelion distances |
context. comets are planetesimals left over from the formation of planets in the solar system. with a growing number of observed molecular abundances in many comets, and an improved understanding of chemical evolution in protoplanetary disk midplanes, comparisons can be made between models and observations that could p... | cometary compositions compared with protoplanetary disk midplane chemical evolution. an emerging chemical evolution taxonomy for comets |
2i/borisov is the first-ever observed interstellar comet (and the second detected interstellar object (iso)). it was discovered on 2019 august 30 and has a heliocentric orbital eccentricity of ∼3.35, corresponding to a hyperbolic orbit that is unbound to the sun. given that it is an iso, it is of interest to compare it... | detection of diatomic carbon in 2i/borisov |
as discovery of complex molecules and ions in our solar system and the interstellar medium has proliferated, several groups have turned to laboratory experiments in an effort to simulate and understand these chemical processes. so far only infrared (ir) and ultraviolet (uv) spectroscopy has been able to directly probe ... | direct detection of complex organic products in ultraviolet (lyα) and electron-irradiated astrophysical and cometary ice analogs using two-step laser ablation and ionization mass spectrometry |
compressed ultrafast photography (cup), a computational imaging technique, is synchronized with short-pulsed laser illumination to enable dynamic three-dimensional (3d) imaging. by leveraging the time-of-flight (tof) information of pulsed light backscattered by the object, tof-cup can reconstruct a volumetric image fro... | encrypted three-dimensional dynamic imaging using snapshot time-of-flight compressed ultrafast photography |
the study of dust, the most abundant material in cometary nuclei, is pivotal in understanding the original materials forming the solar system. measuring the coma phase function provides a tool to investigate the nature of cometary dust. rosetta/osiris sampled the coma phase function of comet 67p/churyumov-gerasimenko, ... | the scattering phase function of comet 67p/churyumov-gerasimenko coma as seen from the rosetta/osiris instrument |
nanotechnology has rapidly entered into human society, revolutionized many areas, including technology, medicine and cosmetics. this progress is due to the many valuable and unique properties that nanomaterials possess. in turn, these properties might become an issue of concern when considering potentially uncontrolled... | genotoxicity of metal oxide nanomaterials: review of recent data and discussion of possible mechanisms |
context. this paper describes the initial modelling of gas and dust data acquired in august and september 2014 from the european space agency's rosetta spacecraft when it was in close proximity to the nucleus of comet 67p/churyumov-gerasimenko.aims: this work is an attempt to provide a self-consistent model of the inne... | modelling observations of the inner gas and dust coma of comet 67p/churyumov-gerasimenko using rosina/cops and osiris data: first results |
this paper describes the simulation and analysis work on rosetta lander philae's touchdown dynamics which was done to support its landing site selection process. the simulation part consists of a numerical multi-body simulation to describe philae's touchdown dynamics. suitable performance metrics in conjunction with mo... | rosetta lander philae - landing performance and touchdown safety assessment |
gas detection around main-sequence stars is becoming more common with around 20 systems showing the presence of co. however, more detections are needed, especially around later spectral type stars to better understand the origin of this gas and refine our models. to do so, we carried out a survey of 10 stars with predi... | survey of planetesimal belts with alma: gas detected around the sun-like star hd 129590 |
the upper atmospheres of unmagnetized solar system bodies interact more directly with their local plasma environment than their counterparts on magnetized bodies such as earth. one consequence of this interaction is that atmospheric particles can gain energy from the flowing plasma, as well as solar photons, and escape... | atmospheric escape from unmagnetized bodies |
comets are thought to have information about the formation process of our solar system. recently, detailed information about comet 67p/churyumov-gerasimenko was found by rosetta. it is remarkable that its tensile strength was estimated. in this paper, we measure and formulate the tensile strength of porous dust aggrega... | tensile strength of porous dust aggregates |
we present individual dynamical masses for the nearby m9.5+t5.5 binary wise j072003.20-084651.2ab, a.k.a. scholz’s star. combining high-precision canada-france-hawaii telescope/wircam photocenter astrometry and keck adaptive optics resolved imaging, we measure the first high-quality parallactic distance ({6.80}-0.06+0.... | wise j072003.20-084651.2b is a massive t dwarf |
context. early observations of comet c/2016 r2 (panstarrs) have shown that the composition of this comet is very peculiar. radio observations have revealed a co-rich and hcn-poor comet and an optical coma dominated by strong emission bands of co+ and, more surprisingly, n2+.aims: the strong detection of n2+ in the coma... | high resolution optical spectroscopy of the n2-rich comet c/2016 r2 (panstarrs) |
based on the occurrence rates implied by the discoveries of 1i/'oumuamua and 2i/borisov, the forthcoming rubin observatory legacy survey of space and time (lsst) should detect ≥one interstellar object every year. we advocate for future measurements of the production rates of h2o, co2, and co in these objects to estimat... | the volatile carbon-to-oxygen ratio as a tracer for the formation locations of interstellar comets |
aims: using spectroscopic and continuum data measured by the miro instrument on board rosetta of comet 67p/churyumov-gerasimenko, it is possible to derive and track the change in the water production rate, to learn how the outgassing evolves with heliocentric distance. the miro data are well suited to investigate the e... | spatially resolved evolution of the local h2o production rates of comet 67p/churyumov-gerasimenko from the miro instrument on rosetta |
context. the rosetta spacecraft arrived at the comet 67p/churyumov-gerasimenko on august 6, 2014, which has made it possible to perform the first study of the solar wind interacting with the coma of a weakly outgassing comet.aims: it is shown that the solar wind experiences large deflections (>45°) in the weak coma.... | rosetta observations of solar wind interaction with the comet 67p/churyumov-gerasimenko |
in this paper we suggest penning ionization as an important route of formation for ionic species in upper planetary atmospheres. our goal is to provide relevant tools to researchers working on kinetic models of atmospheric interest, in order to include penning ionizations in their calculations as fast processes promoti... | the possible role of penning ionization processes in planetary atmospheres |
recent observations of the long-period comet c/2016 r2 (panstarrs; hereafter r2) indicate an unusually high n2/co abundance ratio, typically larger than ∼0.05, and at least 2-3 times higher than the one measured in 67p/churyumov-gerasimenko. another striking compositional feature of this comet is its heavy depletion in... | cold traps of hypervolatiles in the protosolar nebula at the origin of the peculiar composition of comet c/2016 r2 (panstarrs) |
evidence for cometary activity beyond jupiter's and saturn's orbits-such as that observed for centaurs and long-period comets-suggests that the thermal processing of comet nuclei starts long before they enter the inner solar system, where they are typically observed and monitored. such observations raise questions as t... | thermal processing of jupiter-family comets during their chaotic orbital evolution |
the trappist-1 system is unique in that it has a chain of seven terrestrial earth-like planets located close to or in its habitable zone. in this paper, we study the effect of potential cometary impacts on the trappist-1 planets and how they would affect the primordial atmospheres of these planets. we consider both atm... | cometary impactors on the trappist-1 planets can destroy all planetary atmospheres and rebuild secondary atmospheres on planets f, g, and h |
we show that the scattering phase functions of the coma and the nucleus of the comet 67p/churyumov-gerasimenko measured by the rosetta/optical, spectroscopic, and infrared remote imaging system (osiris) instrument can be reproduced by a particle model involving clustered, densely packed submicrometer-sized grains compo... | interpretation of the phase functions measured by the osiris instrument for comet 67p/churyumov-gerasimenko |
we directly measured twenty overhanging cliffs on the surface of comet 67p/churyumov-gerasimenko extracted from the latest shape model and estimated the minimum tensile strengths needed to support them against collapse under the comet's gravity. we find extremely low strengths of around 1 pa or less (1 to 5 pa, when sc... | tensile strength of 67p/churyumov-gerasimenko nucleus material from overhangs |
the exocometary origin of co gas has been confirmed in several extrasolar kuiper belts, with co ice abundances consistent with solar system comets. we here present a molecular survey of the β pictoris belt with the submillimeter array (sma), reporting upper limits for cn, hcn, hco+, n2h+, and h2co, as well as for h2s, ... | molecular reconnaissance of the β pictoris gas disk with the sma: a low hcn/(co+co2) outgassing ratio and predictions for future surveys |
silver nanoparticles (17.78 ± 12.12 nm) were synthesized by the reduction of 0.5 m silver nitrate using formaldehyde as reducing and triethylamine as promoting and stabilizing agent. the particles were grain like agglomerates with spherical, centered-face cubic and crystalline in nature. the sample was highly pure with... | assessment of toxicity in fresh water fish labeo rohita treated with silver nanoparticles |
observations of the coma near the nucleus of comet 67p/churyumov-gerasimenko (67p) made by the ies (ion and electron sensor) instrument onboard the rosetta orbiter during late 2014 showed that electron fluxes greatly exceeded solar wind electron fluxes. the ies is part of the rosetta plasma consortium. this paper repor... | suprathermal electrons near the nucleus of comet 67p/churyumov-gerasimenko at 3 au: model comparisons with rosetta data |
in the first paper of this series, we examined existing methods of optical meteor trajectory estimation and developed a novel method which simultaneously uses both the geometry and the dynamics of meteors to constrain their trajectories. we also developed a simulator which uses an ablation model to generate realistic s... | estimating trajectories of meteors: an observational monte carlo approach - ii. results |
context. one of the main aims of the esa rosetta mission is to study the origin of the solar system by exploring comet 67p/churyumov-gerasimenko at close range.aims: in this paper we discuss the origin and evolution of comet 67p/churyumov-gerasimenko in relation to that of comets in general and in the framework of curr... | comet 67p/churyumov-gerasimenko: constraints on its origin from osiris observations |
mercury's calcium exosphere varies in a periodic way with that planet's true anomaly. we show that this pattern can be explained by impact vaporization from interplanetary dust with variations being due to mercury's radial and vertical excursions through an interplanetary dust disk having an inclination within 5 degree... | impact vaporization as a possible source of mercury's calcium exosphere |
we will briefly recapitulate the beginning of modern cometary physic. then we will assess the results of the cometary flyby missions previous to esa's rosetta rendezvous with comet 67p/churyumov-gerasimenko. emphasis is given to the physical properties of cometary nuclei. we will relate the results of the rosetta missi... | cometary nuclei—from giotto to rosetta |
observations of protoplanetary disks have revealed them to be complex and dynamic, with vertical and radial transport of gas and dust occurring simultaneously with chemistry and planet formation. previous models of protoplanetary disks focused primarily on chemical evolution of gas and dust in a static disk, or dynamic... | chemical feedback of pebble growth: impacts on co depletion and c/o ratios |
context. the esa/rosetta mission made it possible to monitor the plasma environment of a comet, from near aphelion to perihelion conditions. to understand the complex dynamics and plasma structures found at the comet, a modelling effort must be carried out in parallel.aims: firstly, we present a 3d hybrid model of the ... | hybrid modelling of cometary plasma environments. i. impact of photoionisation, charge exchange, and electron ionisation on bow shock and cometopause at 67p/churyumov-gerasimenko |
we report the detection of intense emission from magnesium and iron in mars' atmosphere caused by a meteor shower following comet siding spring's close encounter with mars. the observations were made with the imaging ultraviolet spectrograph, a remote sensing instrument on the mars atmosphere and volatile evolution spa... | maven iuvs observations of the aftermath of the comet siding spring meteor shower on mars |
we construct a 3d map of the spatial density of ob stars within 500 pc from the sun using the hipparcos catalogue and find three large-scale stream-like structures that allow a new view on the solar neighbourhood. the spatial coherence of these blue streams and the monotonic age sequence over hundreds of parsecs sugges... | cosmography of ob stars in the solar neighbourhood |
the previously defined regions on the nucleus of comet 67p/churyumov-gerasimenko have been mapped back onto the 3d shap7 model of the nucleus (preusker et al., 2017). the resulting regional definition is therefore self-consistent with boundaries that are well defined in 3 dimensions. the facets belonging to each region... | regional unit definition for the nucleus of comet 67p/churyumov-gerasimenko on the shap7 model |
this contributed monograph is the first work to present the latest results and findings on the new topic and hot field of planetary exploration and sciences, e.g., lunar surface iron content and mare orientale basalts, earth's gravity field, martian radar exploration, crater recognition, ionosphere and astrobiology, co... | planetary exploration and science: recent results and advances |
context. the rosetta spacecraft is currently escorting comet 67p/churyumov-gerasimenko until its perihelion approach at 1.2 au. this mission has provided unprecedented views into the interaction of the solar wind and the comet as a function of heliocentric distance.aims: we study the interaction of the solar wind and c... | suprathermal electron environment of comet 67p/churyumov-gerasimenko: observations from the rosetta ion and electron sensor |
comet c/2017 k2 (panstarrs) was discovered by the pan-starrs1 (ps1) survey on 2017 may 21 at a distance of 16.09 au from the sun, the second most distant discovery of an active comet. pre-discovery images in the ps1 archive back to 2014 and additional deep cfht images between 2013 may 10-13 showed the comet to be activ... | co-driven activity in comet c/2017 k2 (panstarrs) |
conditions in the protosolar nebula have left their mark in the composition of cometary volatiles, thought to be some of the most pristine material in the solar system. cometary compositions represent the end point of processing that began in the parent molecular cloud core and continued through the collapse of that co... | the composition of the protosolar disk and the formation conditions for comets |
passing stars can perturb the oort cloud, triggering comet showers and potentially extinction events on earth. we combine velocity measurements for the recently discovered, nearby, low-mass binary system wise j072003.20-084651.2 (“scholz’s star”) to calculate its past trajectory. integrating the galactic orbits of this... | the closest known flyby of a star to the solar system |
by using the imagery acquired by the optical, spectroscopic, and infrared remote imaging system wide-angle camera (osiris wac), we prepare a high-resolution morphological map of the rosetta sais final landing site, characterized by an outcropping consolidated terrain unit, a coarse boulder deposit and a fine particle d... | the pebbles/boulders size distributions on sais: rosetta's final landing site on comet 67p/churyumov-gerasimenko |
in the context of an increasing number of complex multiparametric dust coma models it was found convenient to construct an elementary model with a minimum number of parameters selected to represent the key processes acting on the dust. the models outputs can be used as a reference evaluation of these processes with rou... | asymptotics for spherical particle motion in a spherically expanding flow |
in comets, iron and nickel are found in refractory dust particles or in metallic and sulfide grains1. so far, no iron- or nickel-bearing molecules have been observed in the gaseous coma of comets2. iron and a few other heavy atoms, such as copper and cobalt, have been observed only in two exceptional objects: the great... | iron and nickel atoms in cometary atmospheres even far from the sun |
isotopic ratios provide a powerful tool for understanding the origins of materials, including the volatile and refractory matter within solar system bodies. recent high sensitivity observations of molecular isotopologues, in particular with alma, have brought us new information on isotopic ratios of hydrogen, carbon, n... | the isotopic links from planet forming regions to the solar system |
spacecraft charging is problematic for low-energy plasma measurements. the charged particles are attracted to or repelled from the charged spacecraft, affecting both the energy and direction of travel of the particles. the ion composition analyzer (rpc-ica) on board the rosetta spacecraft is suffering from this effect.... | the influence of spacecraft charging on low-energy ion measurements made by rpc-ica on rosetta |
in this investigation, the head-on collision of dust-acoustic (da) multi-solitons in a magnetized space dusty plasma consisting of negative dust, maxwellian electrons and q-nonextensively distributed ions under the influence of polarization force is studied. the presence of the q-nonextensive ions yields eloquent alter... | head-on collision of multi-solitons in a magnetized space dusty plasma in the presence of nonextensive polarization force |
we use observations from the ion and electron sensor (ies) on board the rosetta spacecraft to study the relationship between the cometary suprathermal electrons and the drivers that affect their density and temperature. we fit the ies electron observations with the summation of two kappa distributions, which we charact... | statistical analysis of suprathermal electron drivers at 67p/churyumov-gerasimenko |
context. within just two years, two interstellar objects (isos) - 1i/`oumuamua and 2i/borisov - have been discovered, the first of their kind. large quantities of planetesimals form as a by-product of planet formation. therefore, it seems likely that isos are former planetesimals that became somehow unbound from their ... | significant interstellar object production by close stellar flybys |
aims: far away from the sun, at around 3 au, the activity of comet 67p/churyumov-gerasimenko is low and changes with local time (solar insolation), with location (chemical heterogeneity of the surface), and with season. when the activity is very low because the total cross section of the comet against the sun is small,... | solar wind sputtering of dust on the surface of 67p/churyumov-gerasimenko |
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