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the rosetta ion and electron sensor (ies) has been measuring solar wind ions intermittently since exiting from hibernation in may 2014. on 19 august, when rosetta was ~80 km from the comet 67p/churyumov-gerasimenko, which was ~3.5 au from the sun, ies began to see ions at its lowest energy range, ~4-10 ev. we identify ... | the rosetta ion and electron sensor (ies) measurement of the development of pickup ions from comet 67p/churyumov-gerasimenko |
we summarize unique aperture data on the degree of linear polarization observed for distant comets c/2010 s1, c/2010 r1, c/2011 kp36, c/2012 j1, c/2013 v4, and c/2014 a4 with heliocentric distances exceeding 3 au. observations have been carried out at the 6-m telescope of the special astrophysical observatory of the ru... | retrieval of microphysical characteristics of particles in atmospheres of distant comets from ground-based polarimetry |
context. cyanogen (nccn) is the simplest member of the dicyanopolyynes group, and has been proposed as a major source of the cn radical observed in cometary atmospheres. although not detected through its rotational spectrum in the cold interstellar medium, this very stable species is supposed to be very abundant.aims: ... | isocyanogen formation in the cold interstellar medium |
the structure of the upper layer of a comet is a product of its surface activity. the rosetta lander imaging system (rolis) on board philae acquired close-range images of the agilkia site during its descent onto comet 67p/churyumov-gerasimenko. these images reveal a photometrically uniform surface covered by regolith c... | the structure of the regolith on 67p/churyumov-gerasimenko from rolis descent imaging |
exposure to bisphenol a (bpa) has been related to male reproductive disorders. since this endocrine disruptor also displays genotoxic and epigenotoxic effects, it likely alters the spermatogenesis, a process in which both hormones and chromatin remodeling play crucial roles. the hypothesis of this work is that bpa impa... | genetic and epigenetic alterations induced by bisphenol a exposure during different periods of spermatogenesis: from spermatozoa to the progeny |
the current giant planet region is a transitional zone where transneptunian objects (tnos) cross in their way to becoming jupiter family comets. their dynamical behavior is conditioned by the intrinsic dynamical features of tnos and also by the encounters with the giant planets. we address the giant planet crossing (gp... | centaur and giant planet crossing populations: origin and distribution |
the compositions of planet-forming disks are set by a combination of material inherited from the interstellar medium and material reprocessed during disk formation and evolution. indeed, comets and primitive meteorites exhibit interstellar-like isotopic ratios and/or volatile compositions, supporting that some pristine... | ice inheritance in dynamical disk models |
in an effort to better understand the evolution of composite supernova remnants (snrs) and the eventual fate of relativistic particles injected by their pulsars, we present a multifaceted investigation of the interaction between a pulsar wind nebula (pwn) and its host snr g327.1-1.1. our 350 chandra x-ray observations ... | late-time evolution of composite supernova remnants: deep chandra observations and hydrodynamical modeling of a crushed pulsar wind nebula in snr g327.1-1.1 |
this paper shows how the dips and secular dimming in the kic8462852 light curve can originate in circumstellar material distributed around a single elliptical orbit (e.g. exocomets). the expected thermal emission and wavelength dependent dimming is derived for different orbital parameters and geometries, including dust... | modelling the kic8462852 light curves: compatibility of the dips and secular dimming with an exocomet interpretation |
we measure the absolute magnitude, h, distribution, dn(h) ∝ 10 αh , of the scattering trans-neptunian objects (tnos) as a proxy for their size-frequency distribution. we show that the h-distribution of the scattering tnos is not consistent with a single-slope distribution, but must transition around hg∼ 9 to either a k... | ossos. ii. a sharp transition in the absolute magnitude distribution of the kuiper belt’s scattering population |
inner solar system bodies are depleted in volatile elements relative to chondrite meteorites, yet the source(s) and mechanism(s) of volatile-element depletion and/or enrichment are poorly constrained. the timing, mechanisms and quantities of volatile elements present in the early inner solar system have vast implicatio... | early accretion of water and volatile elements to the inner solar system: evidence from angrites |
we describe the development, launch into space, and initial results from a prototype wide field-of-view soft x-ray imager that employs lobster-eye optics and targets heliophysics, planetary, and astrophysics science. the sheath transport observer for the redistribution of mass is the first instrument using this type of... | invited article: first flight in space of a wide-field-of-view soft x-ray imager using lobster-eye optics: instrument description and initial flight results |
intensive coal mining activities in the upper silesian coal basin (uscb) in southern poland are resulting in large amounts of methane (ch4) emissions. annual ch4 emissions reached 448 kt according to the european pollutant release and transfer register (e-prtr, 2017). as a ch4 emission hotspot in europe, it is of impor... | quantifying ch4 emissions in hard coal mines from tropomi and iasi observations using the wind-assigned anomaly method |
comets are seen as depleted in nitrogen compared to the protosolar value, but a small number exhibit significantly higher than typical n2/co ratios: c/1908 r1 (morehouse), c/1940 r2 (cunningham), c/1947 s1 (bester), c/1956 r1 (arend-roland), c/1957 p1 (mrkos), c/1961 r1 (humason), c/1969 y1 (bennett), c/1973 e1 (kohout... | n2/co ratio in comets insensitive to orbital evolution |
we present a photometric and dynamical study of comet c/2010 u3 (boattini), which was seen active in prediscovery data as early as 2005 november at a new inbound record heliocentric distance of r h = 25.8 au. two outburst events around 2009 and 2017 were observed. the coma and tail of the comet consist of dust grains o... | c/2010 u3 (boattini): a bizarre comet active at record heliocentric distance |
we have conducted the first comprehensive numerical investigation of the relative velocity distribution of dust particles in self-gravitating protoplanetary discs with a view to assessing the viability of planetesimal formation via direct collapse in such environments. the viability depends crucially on the large sizes... | collision velocity of dust grains in self-gravitating protoplanetary discs |
a comprehensive study of the organic chemistry and mineralogy of an ultracarbonaceous micrometeorite (ucamm d05ib80) collected from near the dome fuji station, antarctica, was carried out to understand the genetic relationship among organic materials, silicates, and water. the micrometeorite is composed of a dense aggr... | formation of an ultracarbonaceous antarctic micrometeorite through minimal aqueous alteration in a small porous icy body |
despite a long tradition of dust instruments flown on-board space mission, the largest number of these can be considered unique as they used different detection techniques. giada (grain impact analyzer and dust accumulator), is one of the dust instruments on-board the rosetta spacecraft and is devoted to measure the du... | giada - grain impact analyzer and dust accumulator - onboard rosetta spacecraft: extended calibrations |
hr 8799 is a young f0-type star with four directly imaged giant planets and two debris belts, one located exterior and another one interior to the region occupied by the planetary orbits. not only having an architecture similar to that of our solar system but also revealing dissimilarities such as high masses of planet... | the scattered disc of hr 8799 |
we present resolved images of the hr 4796a debris disk using the magellan adaptive optics system paired with clio-2 and visao. we detect the disk at 0.77 μm, 0.91 μm, 0.99 μm, 2.15 μm, 3.1 μm, 3.3 μm, and 3.8 μm. we find that the deprojected center of the ring is offset from the star by 4.76 ± 1.6 au and that the depro... | on the morphology and chemical composition of the hr 4796a debris disk |
millimeter and centimeter observations are discovering an increasing number of interstellar complex organic molecules (icoms) in a large variety of star-forming sites, from the earliest stages of star formation to protoplanetary disks and in comets. in this context it is pivotal to understand how the solid-phase intera... | thermal desorption of astrophysically relevant ice mixtures of acetaldehyde and acetonitrile from olivine dust |
enceladus harbors an ocean beneath its ice crust that erupts spectacular plumes from fissures at the south pole. the plume composition was measured by the cassini spacecraft, and provides evidence for the ocean's gas content, salinity, ph, and potential for life. understanding the ocean's composition is complicated by ... | chemical fractionation modeling of plumes indicates a gas-rich, moderately alkaline enceladus ocean |
modeling of the electrical conductivity (ec) of icy moon oceans has previously assumed that chloride, sulfate, and other ions released from rock leaching are the main solutes and carriers of ec. here, we show that accreted volatiles, such as carbon dioxide and ammonia, can add a significant fraction of solutes in bodie... | contribution of non-water ices to salinity and electrical conductivity in ocean worlds |
aims: solar orbiter launched in february 2020 with the goal of revealing the connections between the sun's interior, atmosphere, and the heliosphere. the solar orbiter heavy ion sensor (his) is a time-of-flight ion mass spectrometer dedicated to measuring heavy ions in the solar wind.methods: we present an overview of ... | first results from the solar orbiter heavy ion sensor |
context. increasingly, oort cloud comets are being discovered at great distances from the sun and tracked over ever wider ranges of heliocentric distances as observational equipment improves.aims: our goal is to investigate in detail how the original semimajor axis for near-parabolic comets depends on the selected data... | oort cloud comets discovered far from the sun |
we show that if comets (or any small icy planetesimals such as kuiper belt objects) are composed of pebble piles, their internal radiogenic as well as geochemical heating results in considerably different evolutionary outcomes compared to similar past studies. we utilize a 1d thermophysical evolution code, modified to ... | are there any pristine comets? constraints from pebble structure |
because ion-neutral reaction cross sections are energy dependent, the distance from a cometary nucleus within which ions remain collisionally coupled to the neutrals is dictated not only by the comet’s activity level but also by the electromagnetic fields in the coma. here we present a 1d model simulating the outward r... | a 1d model of radial ion motion interrupted by ion-neutral interactions in a cometary coma |
we monitor the inner coma of comet 41p/tuttle-giacobini-kresák searching for variations of its colour. fast changes in colour of the comet 41p/tuttle-giacobini-kresák provide important clues for better understanding of the microphysical properties of its dust. using the 61- and 70-cm telescopes we measured the apparent... | rapid variations of dust colour in comet 41p/tuttle-giacobini-kresák |
context. hyperactive comets are a small group of comets whose activity is higher than expected. they seem to emit more water than would normally be expected given the size of their nucleus. comet 46p/wirtanen (hereafter, 46p) is among these objects of interest. investigating its activity and composition evolution could... | activity and composition of the hyperactive comet 46p/wirtanen during its close approach in 2018 |
despite extensive studies on the formation of organic molecules in various extraterrestrial environments, it still remains under debate when, where, and how such molecules were abiotically formed. a key molecule to solve the problem, hexamethylenetetramine (hmt) has not been confirmed in extraterrestrial materials desp... | extraterrestrial hexamethylenetetramine in meteorites—a precursor of prebiotic chemistry in the inner solar system |
many biological systems display intriguing chiral patterns and dynamics. here, we present an active nematic theory accounting for individual spin to explore the collective handedness in chiral rod-shaped aggregations. we show that coordinated individual spin and motility can engender a vortex-array pattern with chirali... | pattern formation and defect ordering in active chiral nematics |
context. during the most recent perihelion passage in 2009 of comet 67p/churyumov-gerasimenko (67p), ground-based observations showed an anisotropic dust coma where jet-like features were detected at ~ 1.3 au from the sun. the current perihelion passage is exceptional as the rosetta spacecraft is monitoring the nucleus... | large-scale dust jets in the coma of 67p/churyumov-gerasimenko as seen by the osiris instrument onboard rosetta |
comet interceptor (comet-i) was selected in june 2019 as the first esa f-class mission. in 2029+, comet-i will hitch a ride to a sun-earth l2 quasi-halo orbit, as a co-passenger of esa's m4 ariel mission. it will then remain idle at the l2 point until the right departure conditions are met to intercept a yet-to-be-disc... | esa f-class comet interceptor: trajectory design to intercept a yet-to-be-discovered comet |
context. the rosetta encounter with comet 67p/churyumov-gerasimenko provides a unique opportunity for an in situ, up-close investigation of ion-neutral chemistry in the coma of a weakly outgassing comet far from the sun.aims: observations of primary and secondary ions and modeling are used to investigate the role of io... | rosina/dfms and ies observations of 67p: ion-neutral chemistry in the coma of a weakly outgassing comet |
as a result of two years of observations the authors identified twilight class of bolides. unlike the nighttime observations of bright meteor traces that can be seen no more than ten seconds, twilight traces are observed from a few minutes to two hours. the paper considers the synchronous observation of the evening twi... | observations of fragment of cometary nuclei in the atmosphere over kiev |
we present a high-resolution observation of the distant comet c/2014 un271 (bernardinelli-bernstein) using the hubble space telescope on 2022 january 8. the signal of the nucleus was successfully isolated by means of a nucleus extraction technique, with an apparent v-band magnitude measured to be 21.65 ± 0.11, correspo... | hubble space telescope detection of the nucleus of comet c/2014 un271 (bernardinelli-bernstein) |
starting from several monthly data sets of rosetta's cometary pressure sensor, we reconstruct the gas density in the coma around comet 67p/churyumov-gerasimenko. the underlying inverse gas model is constructed by fitting ten thousands of measurements to thousands of potential gas sources distributed across the entire n... | seasonal changes of the volatile density in the coma and on the surface of comet 67p/churyumov-gerasimenko |
context. debris discs have often been described as gas-poor discs as the gas-to-dust ratio is expected to be considerably lower than in primordial, protoplanetary discs. however, recent observations have confirmed the presence of a non-negligible amount of cold gas in the circumstellar (cs) debris discs around young ma... | the co-existence of hot and cold gas in debris discs |
the highly favorable 2017 apparition of 2p/encke allowed the first comprehensive comparison of primary volatile abundances in a given comet across multiple apparitions. this apparition offered opportunities to address pressing questions in cometary science, including investigating evolutionary and/or heliocentric dista... | a tale of “two” comets: the primary volatile composition of comet 2p/encke across apparitions and implications for cometary science |
exocomets are small bodies releasing gas and dust which orbit stars other than the sun. their existence was first inferred from the detection of variable absorption features in stellar spectra in the late 1980s using spectroscopy. more recently, they have been detected through photometric transits from space, and throu... | exocomets from a solar system perspective |
the first computational model of solid-phase chemistry in cometary nuclear ices is presented. an astrochemical kinetics model, the model for astrophysical gas and ice chemical kinetics and layering, is adapted to trace the chemical evolution in multiple layers of cometary ice, over a representative period of 5 gyr. phy... | simulations of ice chemistry in cometary nuclei |
context. the presence or absence of ice in protoplanetary disks is of great importance to the formation of planets. by enhancing solid surface density and increasing sticking efficiency, ice catalyzes the rapid formation of planetesimals and decreases the timescale of giant planet core accretion.aims: in this paper, we... | the abundance and thermal history of water ice in the disk surrounding hd 142527 from the digit herschel key program |
we report production rates for h2o and eight trace molecules (co, c2h6, ch4, ch3oh, nh3, h2co, hcn, c2h2) in the dynamically new, sun-grazing comet c/2012 s1 (ison), using high-resolution spectroscopy at keck ii and the nasa irtf on 10 pre-perihelion dates encompassing heliocentric distances rh = 1.21-0.34 au. measured... | en route to destruction: the evolution in composition of ices in comet d/2012 s1 (ison) between 1.2 and 0.34 au from the sun as revealed at infrared wavelengths |
comet dust is primitive and shows significant diversity. our knowledge of the properties of primitive cometary particles has expanded significantly through microscale investigations of cosmic dust samples (anhydrous interplanetary dust particles (idps), chondritic porous (cp) idps and ultracarbonaceous antarctic microm... | cometary dust: the diversity of primitive refractory grains |
the formation of stars and planetary systems is a complex phenomenon that relies on the interplay of multiple physical processes. nonetheless, it represents a crucial stage for our understanding of the universe, and in particular of the conditions leading to the formation of key molecules (e.g. water) on comets and pla... | on the low ortho-to-para h2 ratio in star-forming filaments |
primordial black holes (pbhs) formed in the early universe are sources of neutrinos emitted via hawking radiation. such astrophysical neutrinos could be detected at earth and constraints on the abundance of comet-mass pbhs could be derived from the null observation of this neutrino flux. here, we consider non-rotating ... | current and future neutrino limits on the abundance of primordial black holes |
aims: the aim of our work is to analyze the light curves of β pic which were recently observed by the transiting exoplanet survey satellite (tess) in sectors 32, 33, and 34 by searching for the signatures of exocomet transits.methods: we processed the β pic light curves from the mikulski archive for space telescopes da... | new exocomets of β pic |
understanding the chemical past of our sun and how life appeared on earth is no mean feat. the best strategy we can adopt is to study newborn stars located in an environment similar to the one in which our sun was born and assess their chemical content. in particular, hot corinos are prime targets because recent studie... | the chemical nature of orion protostars: are oranges different from peaches? oranges ii. |
we study the evolution of the plasma environment of comet 67p using measurements of the spacecraft potential from early september 2014 (heliocentric distance 3.5 au) to late march 2015 (2.1 au) obtained by the langmuir probe instrument. the low collision rate keeps the electron temperature high (∼5 ev), resulting in a ... | evolution of the plasma environment of comet 67p from spacecraft potential measurements by the rosetta langmuir probe instrument |
context. the electrostatic potential of a spacecraft, vs, is important for the capabilities of in situ plasma measurements. rosetta has been found to be negatively charged during most of the comet mission and even more so in denser plasmas.aims: our goal is to investigate how the negative vs correlates with electron de... | a charging model for the rosetta spacecraft |
four interplanetary corotating interaction regions (cirs) were identified during 2016 june-september by the rosetta plasma consortium (rpc) monitoring in situ the plasma environment of the comet 67p/churyumov-gerasimenko (67p) at heliocentric distances of ∼3-3.8 au. the cirs, formed in the interface region between low-... | cometary plasma response to interplanetary corotating interaction regions during 2016 june-september: a quantitative study by the rosetta plasma consortium |
we report the first in situ detection of metal ions in the upper atmosphere of mars resulting from the ablation of dust particles from comet siding spring. this detection was carried out by the neutral gas and ion mass spectrometer on board the mars atmosphere and volatile evolution mission. metal ions of na, mg, al, k... | metallic ions in the upper atmosphere of mars from the passage of comet c/2013 a1 (siding spring) |
aims.we carried out an investigation of the surface variegation of comet 67p/churyumov-gerasimenko, the detection of regions showing activity, the determination of active and inactive surface regions of the comet with spectral methods, and the detection of fallback material.methods: we analyzed multispectral data gener... | variegation of comet 67p/churyumov-gerasimenko in regions showing activity |
the rosetta mission arrived at comet 67 p/churyumov-gerasimenko in summer 2014, after more than 10 years in space. all previous mission encounters with a comet have provided a snapshot of the cometary activity at a given heliocentric distance. in contrast, rosetta has escorted the comet nucleus for an extended period (... | the science planning process on the rosetta mission |
solar heating of a cometary surface provides the energy necessary to sustain gaseous activity, through which dust is removed1,2. in this dynamical environment, both the coma3,4 and the nucleus5,6 evolve during the orbit, changing their physical and compositional properties. the environment around an active nucleus is p... | an orbital water-ice cycle on comet 67p from colour changes |
context. on 12 november 2014 the european mission rosetta succeeded in delivering a lander, named philae, on the surface of one of the smallest, low-gravity and most primitive bodies of the solar system, the comet 67p/churyumov-gerasimenko (67p).aims: the aim of this paper is to provide a comprehensive geomorphological... | geomorphology and spectrophotometry of philae's landing site on comet 67p/churyumov-gerasimenko |
virtis-m observations of the nucleus of comet 67p/churyumov-gerasimenko acquired from 2014 august to 2015 may have been analysed to investigate surface temporal variability at both seasonal and diurnal scales. the measured reflectance spectra are studied by means of comet spectral indicators (csi) such as slopes in the... | the global surface composition of 67p/churyumov-gerasimenko nucleus by rosetta/virtis. ii) diurnal and seasonal variability |
we use published models of the early solar system evolution with a slow, long-range and grainy migration of neptune to predict the orbital element distributions and the number of modern-day centaurs. the model distributions are biased by the outer solar system origins survey (ossos) simulator and compared with the osso... | ossos. xix. testing early solar system dynamical models using ossos centaur detections |
the discovery of the second interstellar object 2i/borisov on 2019 august 30 raises the question of whether it was ejected recently from a nearby stellar system. here we compute the asymptotic incoming trajectory of 2i/borisov, based on both recent and pre-discovery data extending back to december 2018, using a range o... | a search for the origin of the interstellar comet 2i/borisov |
comets are small bodies thought to contain the most pristine material in the solar system. however, since their formation ≈4.5 gy ago, they have been altered by different processes. while not exposed to much electromagnetic radiation, they experience intense particle radiation. galactic cosmic rays and solar energetic ... | the effect of cosmic rays on cometary nuclei. i. dose deposition |
the wide angle camera of the osiris instrument on board the rosetta spacecraft is equipped with several narrow-band filters that are centered on the emission lines and bands of various fragment species. these are used to determine the evolution of the production and spatial distribution of the gas in the inner coma of ... | changes in the physical environment of the inner coma of 67p/churyumov-gerasimenko with decreasing heliocentric distance |
most known trans-neptunian objects (tnos) that gravitationally scatter off the giant planets have orbital inclinations that are consistent with an origin from the classical kuiper belt; however, a small fraction of these “scattering tnos” have inclinations that are far too large (i > 45°) for this origin. these scat... | ossos. xv. probing the distant solar system with observed scattering tnos |
comet 2i/borisov is the first true interstellar comet discovered. here, we present results from observational programs at two indian observatories, 2 m himalayan chandra telescope at the indian astronomical observatory, hanle (hct) and 1.2 m telescope at the mount abu infrared observatory (miro). two epochs of imaging ... | activity of the first interstellar comet 2i/borisov around perihelion: results from indian observatories |
on 31 august 2019, an interstellar comet was discovered as it passed through the solar system (2i/borisov). on the basis of initial imaging observations, 2i/borisov seemed to be similar to ordinary solar system comets1,2—an unexpected characteristic given the multiple peculiarities of the only known previous interstell... | gaseous atomic nickel in the coma of interstellar comet 2i/borisov |
previously proposed mechanisms have difficulty explaining the disruption of comet c/2012 s1 (ison) as it approached the sun. we describe a novel cometary disruption mechanism whereby comet nuclei fragment and disperse through dynamic sublimation pressure, which induces differential stresses within the interior of the n... | dynamic sublimation pressure and the catastrophic breakup of comet ison |
we present a model to account for the observed debris discs around young white dwarfs and the presence of metal lines in their spectra. stellar evolution models predict that the mass-loss on the agb will be pulsed; furthermore, observations indicate that the bulk of the mass-loss occurs on the agb. in this case, if the... | polluting white dwarfs with perturbed exo-comets |
in 2004, the rosetta spacecraft was sent to comet 67p/churyumov-gerasimenko for the first ever long-term investigation of a comet. after its arrival in 2014, the spacecraft spent more than two years in immediate proximity to the comet. during these two years, the rosina double focusing mass spectrometer (dfms) onboard ... | cho-bearing molecules in comet 67p/churyumov-gerasimenko |
we present a study of comet c/2017 k2 (panstarrs) using pre-discovery archival data taken from 2013 to 2017. our measurements show that the comet has been marginally increasing in activity since at least 2013 may (heliocentric distance of {r}{{h}}=23.7 {au} pre-perihelion). we estimate the mass-loss rate during the per... | pre-discovery observations and orbit of comet c/2017 k2 (panstarrs) |
context. the diffusion of volatile species on amorphous solid water ice affects the chemistry on dust grains in the interstellar medium as well as the trapping of gases enriching planetary atmospheres or present in cometary material.aims: the aim of the work is to provide diffusion coefficients of ch4 on amorphous soli... | diffusion of ch4 in amorphous solid water |
in this series of papers, we present statistical maps of mirror-mode-like (mm) structures in the magnetosheaths of mars and venus and calculate the probability of detecting them in spacecraft data. we aim to study and compare them with the same tools and a similar payload at both planets. we consider their dependence o... | statistical distribution of mirror-mode-like structures in the magnetosheaths of unmagnetised planets - part 1: mars as observed by the maven spacecraft |
in recent decades, several missions have detected signs of water and other volatiles in cold, permanently shadowed craters near the lunar poles. observations suggest that some of these volatiles could have been delivered by comet impacts and therefore, understanding the impact delivery mechanism becomes key to explaini... | transport of water in a transient impact-generated lunar atmosphere |
exposure to coal mining dust poses a substantial health hazard to individuals due to the complex mixture of components released during the extraction process. this study aimed to assess the oxidative potential of residual coal mining dust on human lymphocyte dna and telomeres and to perform a chemical characterization ... | the dangerous link between coal dust exposure and dna damage: unraveling the role of some of the chemical agents and oxidative stress |
the interaction between a comet and the impinging solar wind leads to modifications of the magnetic field in the environment of a comet. among those, one finds magnetic field pile-up and draping, which reveal properties of the interaction and are known from previous cometary spacecraft missions. this work studies the m... | magnetic field pile-up and draping at intermediately active comets: results from comet 67p/churyumov-gerasimenko at 2.0 au |
the upper silesian coal basin in poland is one of the major european hotspots of ch4 release. until now, no data concerning short-term ch4 emissions from coal mines have been accessible worldwide. they are available only on a yearly timescale. no values are provided on a higher temporal scale, that's why the measuremen... | polish underground coal mines as point sources of methane emission to the atmosphere |
the discovery of ’oumuamua (1i/2017 u1), the first interstellar interloper, suggests an abundance of free-floating small bodies whose ejection into galactic space cannot be explained by the current population of confirmed exoplanets. shortly after ’oumuamua’s discovery, observational results from the disk substructures... | hidden planets: implications from ’oumuamua and dsharp |
during the short period of our observations (from march 2013 to 2015), was fixed falling at least a dozen fragments of cometary nuclei, at least five of sufficiently large and dozens of smaller fragments of meteoroids. the results of our observations also showed that during the morning and evening twilight over kiev cl... | several twilight bolides over kiev in 2013-2015 - fragments of comets nuclei |
the accelerometers of the sesame/casse instrument aboard rosetta's lander philae recorded surface waves produced during the mupus hammering phase. after presenting evidence that all feet of philae were in contact with the ground, we analyze group arrival time differences between the three feet of philae and obtain a ra... | structure and elastic parameters of the near surface of abydos site on comet 67p/churyumov-gerasimenko, as obtained by sesame/casse listening to the mupus insertion phase |
recent measurements carried out at comet 67p/churyumov-gerasimenko (67p) with the rosetta probe revealed that molecular oxygen, o2, is the fourth most abundant molecule in comets. models show that o2 is likely of primordial nature, coming from the interstellar cloud from which our solar system was formed. however, gase... | linking interstellar and cometary o2: a deep search for 16o18o in the solar-type protostar iras 16293-2422 |
the isotopic ratios are diagnostics for the physico-chemical conditions governing molecular formation. in comets, 14n/15n ratios have been measured from hcn in three comets and from cn in more than 20 comets. those ratios are enriched in 15n compared to the sun by a factor of ∼3, have a small diversity and do not depen... | nitrogen isotopic ratios of nh2 in comets: implication for 15n-fractionation in cometary ammonia |
the ratios of the three stable oxygen isotopes 16o, 17o, and 18o on the earth and, as far as we know in the solar system, show variations on the order of a few per cent at most, with a few outliers in meteorites. however, in the interstellar medium there are some highly fractionated oxygen isotopic ratios in some speci... | molecule-dependent oxygen isotopic ratios in the coma of comet 67p/churyumov-gerasimenko |
the orbital architecture of the solar system is thought to have been sculpted by a dynamical instability among the giant planets. during the instability a primordial outer disk of planetesimals was destabilized and ended up on planet-crossing orbits. most planetesimals were ejected into interstellar space, but a fracti... | survivor bias: divergent fates of the solar system's ejected versus persisting planetesimals |
with an increasing number of parameters and pre-training data, generative large language models (llms) have shown remarkable capabilities to solve tasks with minimal or no task-related examples. notably, llms have been successfully employed as evaluation metrics in text generation tasks. within this context, we introdu... | the eval4nlp 2023 shared task on prompting large language models as explainable metrics |
aims: the rosetta space probe accompanied comet 67p/churyumov-gerasimenko for more than two years, obtaining an unprecedented amount of unique data of the comet nucleus and inner coma. this has enabled us to study its activity almost continuously from 4 au inbound to 3.6 au outbound, including the perihelion passage at... | linking surface morphology, composition, and activity on the nucleus of 67p/churyumov-gerasimenko |
we present chemical abundances and radial velocities of six h ii regions in the extremely metal-poor star-forming dwarf galaxy ddo 68. they are derived from deep spectra in the wavelength range 3500-10 000 å, acquired with the multi-object double spectrograph at the large binocular telescope (lbt). in the three regions... | chemical abundances and radial velocities in the extremely metal-poor galaxy ddo 68 |
polarization arising from aligned dust grains presents a unique opportunity to study magnetic fields in the diffuse interstellar medium and molecular clouds. polarization from circumstellar regions, accretion disks and comet atmospheres can also be related to aligned dust.to reliably trace magnetic fields quantitative ... | grain alignment: role of radiative torques and paramagnetic relaxation |
we test the hypothesis that an annually repeatable ca emission excess in mercury's exosphere at a true anomaly angle (taa) of 25° ± 5° is due to particles from comet 2p/encke impacting the surface. by simulating the dynamical evolution of encke particles under planetary perturbations and poynting-robertson drag, we fin... | the meteoroid stream of comet encke at mercury: implications for mercury surface, space environment, geochemistry, and ranging observations of the exosphere |
comets are made of volatile and refractory material and naturally experience various degrees of sublimation as they orbit around the sun. this gas release, accompanied by dust, represents what is traditionally described as activity. although the basic principles are well established, most details remain elusive, especi... | local manifestations of cometary activity |
we analyze the first color and polarization images of comet ison (c/2012 s1) taken during two measurement campaigns of the hubble space telescope (hst) on utc 2013 april 10 and may 8, when the phase angles of comet ison were α≈13.7° and 12.2°, respectively. we model the particles in the coma using highly irregular aggl... | comet c/2012 s1 (ison) coma composition at ~4 au from hst observations |
we carried out photometric and spectroscopic observations of comet 29p/schwassmann-wachmann 1 at the 6-m bta telescope (sao ras, russia) and the 1.6-m telescope of the national laboratory for astrophysics (lna, brazil) on february 20, 2012, and on may 31, 2011, respectively. the spectra revealed the presence of co+ and... | photometric and spectroscopic analysis of comet 29p/schwassmann-wachmann 1 activity |
context. the cometary ionosphere is immersed in fast flowing solar wind. a polarisation electric field may arise for comets much smaller than the gyroradius of pickup ions because ions and electrons respond differently to the solar wind electric field.aims: a situation similar to that found at a low activity comet has ... | size of a plasma cloud matters. the polarisation electric field of a small-scale comet ionosphere |
the present study aims to evaluate the potential genotoxic and associated factors among coal miners, divided by degree of exposure. blood and buccal smears were collected from 158 workers, who actively participate in different activities in coal mining, and 48 individuals living in the same city but do not have partici... | genotoxicity in brazilian coal miners and its associated factors |
context. ultracarbonaceous antarctic micrometeorites (ucamms) represent a small fraction of interplanetary dust particles reaching the earth's surface and contain large amounts of an organic component not found elsewhere. they are most probably sampling a contribution from the outer regions of the solar system to the l... | dome c ultracarbonaceous antarctic micrometeorites. infrared and raman fingerprints |
organic matter has been continuously delivered by meteorites and comets to mars since its formation, and possibly formed in situ by abiogenic and/or biogenic processes. this organic matter may be preserved from the harsh oxidizing environment of mars in specific locations. together with water, organic molecules are nec... | analysis of carbon and nitrogen signatures with laser-induced breakdown spectroscopy; the quest for organics under mars-like conditions |
the effect of ionizing radiation on solid methane has previously been an area of interest in the astrophysics community. in the late 1980s this interest was further boosted by the possibility of using solid methane as a moderating medium in spallation neutron sources. here we present test results of solid methane moder... | solid methane in neutron radiation: cryogenic moderators and cometary cryo volcanism |
high levels of dust have been detected in the immediate vicinity of many stars, both young and old. a promising scenario to explain the presence of this short-lived dust is that these analogues to the zodiacal cloud (or exozodis) are refilled in situ through cometary activity and sublimation. as the reservoir of comets... | inner mean-motion resonances with eccentric planets: a possible origin for exozodiacal dust clouds |
the southern hemisphere of the 67p/churyumov-gerasimenko comet has become visible from rosetta only since 2015 march. it was illuminated during the perihelion passage and therefore it contains the regions that experienced the strongest heating and erosion rates, thus exposing the sub-surface most pristine material. in ... | the highly active anhur-bes regions in the 67p/churyumov-gerasimenko comet: results from osiris/rosetta observations |
we present a statistical analysis of the distribution of large-scale topographic features on comet 67p/churyumov-gerasimenko. we observe that the cumulative cliff height distribution across the surface follows a power law with a slope equal to -1.69 ± 0.02. when this distribution is studied independently for each regio... | constraints on cometary surface evolution derived from a statistical analysis of 67p's topography |
context. there remain many open questions relating to the depletion of elements into dust, e.g., exactly how are c and o incorporated into dust in dense clouds and, in particular, what drives the disappearance of oxygen in the denser interstellar medium?aims: this work is, in part, an attempt to explain the apparently ... | the essential elements of dust evolution. a viable solution to the interstellar oxygen depletion problem? |
context. solar wind charge-changing reactions are of paramount importance to the physico-chemistry of the atmosphere of a comet. the esa/rosetta mission to comet 67p/churyumov-gerasimenko (67p) provides a unique opportunity to study charge-changing processes in situ.aims: to understand the role of these reactions in th... | solar wind charge exchange in cometary atmospheres. iii. results from the rosetta mission to comet 67p/churyumov-gerasimenko |
investigations of the low-temperature radiation-induced transformations in the c2h2-h2o system are relevant to the chemistry occurring in interstellar and cometary ices. in this work, we applied a matrix isolation technique to study the radiation-driven evolution of this system at molecular level in order to get new me... | radiation-induced chemistry in the c2h2-h2o system at cryogenic temperatures: a matrix isolation study |
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