abstract stringlengths 3 192k | title stringlengths 4 857 |
|---|---|
context: co is an abundant species in comets, creating co$^+$ ion with emission lines that can be observed in the optical spectral range. a good modeling of its fluorescence spectrum is important for a better measurement of the co$^+$ abundance. such a species, if abundant enough, can also be used to measure the $^{12}... | comets $^{12}$co$^+$ and $^{13}$co$^+$ fluorescence models for measuring the $^{12}$c/$^{13}$c isotopic ratio in co$^+$ |
context. comets are remnants of the icy planetesimals that formed beyond the ice line in the solar nebula. growing from μm-sized dust and ice particles to km-sized objects is, however, difficult because of growth barriers and time scale constraints. the gravitational collapse of pebble clouds that formed through the st... | comet formation in collapsing pebble clouds. what cometary bulk density implies for the cloud mass and dust-to-ice ratio |
galaxy clusters are known to harbour magnetic fields, the nature of which remains unresolved. intra-cluster magnetic fields can be observed at the density contact discontinuity formed by cool and dense plasma running into hot ambient plasma1,2, and the discontinuity exists3 near the second-brightest galaxy4, mrc 0600-3... | jets from mrc 0600-399 bent by magnetic fields in the cluster abell 3376 |
previous studies of cometary impacts in the outer solar system used the spatial distribution of ecliptic comets (ecs) from dynamical models that assumed ecs began on low-inclination orbits (≲5°) in the kuiper belt. in reality, the source population of ecs-the trans-neptunian scattered disk-has orbital inclinations reac... | impact rates in the outer solar system |
the astrochemistry of co2 ice analogues has been a topic of intensive investigation due to the prevalence of co2 throughout the interstellar medium and the solar system, as well as the possibility of it acting as a carbon feedstock for the synthesis of larger, more complex organic molecules. in order to accurately disc... | mid-ir and vuv spectroscopic characterisation of thermally processed and electron irradiated co2 astrophysical ice analogues |
scientists use the earth as a tool for astrobiology by analyzing planetary field analogues (i.e. terrestrial samples and field sites that resemble planetary bodies in our solar system). in addition, they expose the selected planetary field analogues in simulation chambers to conditions that mimic the ones of planets, m... | earth as a tool for astrobiology—a european perspective |
we present a study of interstellar comet 2i/2019 q4 (borisov) using both preperihelion and postperihelion observations spanning late september 2019 through late january 2020. the intrinsic brightness of the comet was observed to continuously decline throughout the timespan, likely due to the decreasing effective scatte... | physical characterization of interstellar comet 2i/2019 q4 (borisov) |
the spectrum of dicarbon (c2) is important in astrophysics and for spectroscopic studies of plasmas and flames. the c2 spectrum is characterized by many band systems with new ones still being actively identified; astronomical observations involve eight of these bands. recently, furtenbacher et al. presented a set of 56... | an update to the marvel data set and exomol line list for 12c2 |
remote observations of comets, especially using high spectral resolution millimeter spectroscopy, have enabled the detection of over 25 molecules in comets for the last twenty years. among the molecules identified at radio wavelengths, complex organic molecules (coms) such as acetaldehyde, ethylene-glycol, formamide, m... | complex organic molecules in comets from remote-sensing observations at millimeter wavelengths |
measurements of midrapidity charged particle multiplicity distributions, $dn_{\rm ch}/d\eta$, and midrapidity transverse-energy distributions, $de_t/d\eta$, are presented for a variety of collision systems and energies. included are distributions for au$+$au collisions at $\sqrt{s_{_{nn}}}=200$, 130, 62.4, 39, 27, 19.6... | transverse energy production and charged-particle multiplicity at midrapidity in various systems from $\\sqrt{s_{nn}}=7.7$ to 200 gev |
recent field experiments conducted in the near-wake (up to 0.5 rotor diameters downwind of the rotor) of a 2.5 mw wind turbine using snow-based super-large-scale particle image velocimetery (slpiv) (hong et al., nature comm., vol. 5, 2014, no. 4216) were successful in visualizing tip vortex cores as areas devoid of sno... | coherent dynamics in the rotor tip shear layer of utility-scale wind turbines |
we use neowise data from the four-band and three-band cryogenic phases of the wide-field infrared survey explorer mission to constrain size distributions of the comet populations and debias measurements of the short- and long-period comet (lpc) populations. we find that the fit to the debiased lpc population yields a c... | debiasing the neowise cryogenic mission comet populations |
hubble space telescope observations of interstellar comet 2i/borisov near perihelion show the ejection of large ( $\gtrsim 100$ μm) particles at $\lesssim 9$ m s-1 speeds, with estimated mass-loss rates of ∼35 kg s-1. the total mass loss from comet borisov corresponds to loss of a surface shell on the nucleus only ∼0.4... | coma anisotropy and the rotation pole of interstellar comet 2i/borisov |
interstellar complex organic molecules are thought to be the building blocks of more complex prebiotic compounds. in particular, formamide (or methanimide, nh2cho), is presented as a multifunctional prebiotic precursor, the starting point of both pre-genetic and pre-metabolic species. nh2cho is widely observed in diffe... | efficient formation route of the prebiotic molecule formamide on interstellar dust grains |
meteorites, fe and si-rich microspherules, positive ir and pt anomalies, and burned charcoal-rich hopewell habitation surfaces demonstrate that a cosmic airburst event occurred over the ohio river valley during the late holocene. a comet-shaped earthwork was constructed near the airburst epicenter. twenty-nine radiocar... | retracted article: the hopewell airburst event, 1699-1567 years ago (252-383 ce) |
the polar regions of the moon host some of the most extreme low temperatures in the inner solar system due to its low obliquity, lack of atmosphere, and topographic relief. some of these regions are already confirmed to host water ice. proposed sources of water and other volatiles include lunar volcanic outgassing, sol... | spatial distribution and thermal diversity of surface volatile cold traps at the lunar poles |
methane (ch4) is the second most important anthropogenic greenhouse gas, whose atmospheric concentration is modulated by human-induced activities, and it has a larger global warming potential than carbon dioxide (co2). because of its short atmospheric lifetime relative to that of co2, the reduction of the atmospheric a... | quantification of ch4 coal mining emissions in upper silesia by passive airborne remote sensing observations with the methane airborne mapper (mamap) instrument during the co2 and methane (comet) campaign |
we present the first alma dust polarization observations toward the high-mass star-forming regions w51 e2, e8, and w51 north in band 6 (230 ghz) with a resolution of about 0\buildrel{\prime\prime}\over{.} 26 (∼5 mpc). polarized emission in all three sources is clearly detected and resolved. measured relative polarizati... | polarization properties and magnetic field structures in the high-mass star-forming region w51 observed with alma |
nitrogen-bearing molecules in cold molecular clouds exhibit a range of isotopic fractionation ratios and these molecules may be the precursors of 15n enrichments found in comets and meteorites. chemical model calculations indicate that atom-molecular ion and ion-molecule reactions could account for most of the fraction... | revised models of interstellar nitrogen isotopic fractionation |
we present observations showing inbound long-period comet c/2017 k2 (panstarrs) to be active at a record heliocentric distance. nucleus temperatures are too low (60-70 k) either for water ice to sublimate or for amorphous ice to crystallize, requiring another source for the observed activity. using the hubble space tel... | a comet active beyond the crystallization zone |
galaxies can grow through their mutual gravitational attraction and subsequent union. while orbiting a regular high-surface-brightness galaxy, the body of a low-mass galaxy can be stripped away. however, the stellar heart of the infalling galaxy, if represented by a tightly bound nuclear star cluster, is more resilient... | potential black hole seeding of the spiral galaxy ngc 4424 via an infalling star cluster |
the interstellar traveller, 2i/borisov, is the first clearly active extrasolar comet ever detected in our solar system. we obtained high-resolution interferometric observations of 2i/borisov with the atacama large millimeter/submillimeter array (alma) and multi-colour optical observations with the very large telescope ... | compact pebbles and the evolution of volatiles in the interstellar comet 2i/borisov |
in the context of the recently proposed contact-binary model (sekanina 2021), i investigate the circumstances of the first perihelion passage of the kreutz sungrazers in orbits with barycentric periods near 735 yr, following the initial near-aphelion splitting of the presumed progenitor, aristotle's comet of 372 bc. gi... | unprecedented daylight display of kreutz sungrazers in ad 363? |
giada (grain impact analyzer and dust accumulator) on-board the rosetta space probe is designed to measure the momentum, mass and speed of individual dust particles escaping the nucleus of comet 67p/churyumov-gerasimenko (hereafter 67p). from 2014 august to 2016 june, rosetta escorted comet 67p during its journey aroun... | 67p/c-g inner coma dust properties from 2.2 au inbound to 2.0 au outbound to the sun |
reflectance of cometary dust is a key parameter used in the characterization of comets. in the literature, the reflectance of single-scattering cometary dust particles is widely assumed to be the same as that of the cometary nucleus. we discuss this assumption and demonstrate its inconsistency with photometric observat... | on the reflectance of dust in comets |
the plasma environment has been measured for the first time near the surface of a comet. this unique data set has been acquired at 67p/churyumov-gerasimenko during esa/rosetta spacecraft's final descent on 2016 september 30. the heliocentric distance was 3.8 au and the comet was weakly outgassing. electron density was ... | vertical structure of the near-surface expanding ionosphere of comet 67p probed by rosetta |
context. while exoplanets are now routinely detected, the detection of small bodies in extrasolar systems remains challenging. since the discovery of sporadic events, which are interpreted to be exocomets (falling evaporating bodies) around β pic in the early 1980s, only ∼20 stars have been reported to host exocomet-li... | exocomets: a spectroscopic survey |
kic 8462852 is a completely ordinary f3 main-sequence star, except that the light curve from kepler shows episodes of unique and inexplicable day-long dips with up to 20% dimming. here, i provide a light curve of 1338 johnson b-band magnitudes from 1890 to 1989 taken from archival photographic plates at harvard. kic 84... | kic 8462852 faded at an average rate of 0.164 ± 0.013 magnitudes per century from 1890 to 1989 |
motivated by recent visits from interstellar comets, along with continuing discoveries of minor bodies in orbit of the sun, this paper studies the capture of objects on initially hyperbolic orbits by our solar system. using an ensemble of ∼500 million numerical experiments, this work generalizes previous treatments by ... | on the capture of interstellar objects by our solar system |
glycolaldehyde is a key molecule in the formation of biologically relevant molecules such as ribose. we report its detection with the plateau de bure interferometer toward the class 0 young stellar object ngc 1333 iras2a, which is only the second solar-type protostar for which this prebiotic molecule is detected. local... | detection of glycolaldehyde toward the solar-type protostar ngc 1333 iras2a |
spacecraft missions have resolved the nuclei of six periodic comets and revealed a set of geologically intriguing and active small bodies. the shapes of these cometary nuclei are dominantly bilobate reflecting their formation from smaller cometesimals. cometary surfaces include a diverse set of morphologies formed from... | evidence for geologic processes on comets |
a major upgrade to the nirspec instrument at the keck ii telescope was successfully completed in time for near-infrared spectroscopic observations of comet 46p/wirtanen during its exceptionally close flyby of earth in 2018 december. these studies determined the abundances of several volatiles, including c2h2, c2h6, ch3... | first comet observations with nirspec-2 at keck: outgassing sources of parent volatiles and abundances based on alternative taxonomic compositional baselines in 46p/wirtanen |
we present the results of our orbital computations in support of the recently proposed contact-binary model for the kreutz sungrazer system (sekanina 2021, 2022). we demonstrate that comet ikeya-seki (c/1965 s1) previously passed perihelion decades after the great comet of 1106 (x/1106 c1) and argue that, like the grea... | the great comet of 1106, a chinese comet of 1138, and daylight comets in late 363 as key objects in computer simulated history of kreutz sungrazer system |
recent observational and experimental evidence for the presence of complex organics in space is reviewed. remote astronomical observations have detected ∼ 200 gas-phased molecules through their rotational and vibrational transitions. many classes of organic molecules are represented in this list, including some precurs... | complex organics in space from solar system to distant galaxies |
in order to explore the link between comet 81p/wild 2 and materials in primitive meteorites, seven particles 5 to 15 μm in diameter from comet 81p/wild 2 have been analyzed for their oxygen isotope ratios using a secondary ion mass spectrometer. most particles are single minerals consisting of olivine or pyroxene with ... | origin of crystalline silicates from comet 81p/wild 2: combined study on their oxygen isotopes and mineral chemistry |
discs of dusty debris around main-sequence stars indicate fragmentation of orbiting planetesimals, and for a few a-type stars, a gas component is also seen that may come from collisionally released volatiles. here we find the sixth example of a co-hosting disc, around the ∼30 myr-old a0-star hd 32997. two more of these... | gas and dust around a-type stars at tens of myr: signatures of cometary breakup |
the european space agency spacecraft rosetta accompanied the jupiter-family comet 67p/churyumov-gerasimenko for over 2 yr along its trajectory through the inner solar system. between 2014 and 2016, it performed almost continuous in situ measurements of the comet's gaseous atmosphere in close proximity to its nucleus. i... | 16o/18o ratio in water in the coma of comet 67p/churyumov-gerasimenko measured with the rosetta/rosina double-focusing mass spectrometer |
this paper provides a brief overview of the journey of molecules through the cosmos, from local diffuse interstellar clouds and pdrs to distant galaxies, and from cold dark clouds to hot star-forming cores, protoplanetary disks, planetesimals and exoplanets. recent developments in each area are sketched and the importa... | astrochemistry: overview and challenges |
charge exchange (cx) has emerged in x-ray emission modeling as a significant process that must be considered in many astrophysical environments—particularly comets. comets host an interaction between solar wind ions and cometary neutrals to promote solar wind charge exchange (swcx). x-ray observatories provide astronom... | line ratios for solar wind charge exchange with comets |
the philae lander accomplished the first soft landing and the first scientific experiments of a human-made spacecraft on the surface of a comet. planned, expected and unexpected activities and events happened during the descent, the touch-downs, the hopping across and the stay and operations on the surface. the key res... | the philae lander mission and science overview |
the isotopic ratio of nitrogen measured in primitive solar system bodies shows a broad range of values, the origin of which remains unknown. one key question is whether these isotopic reservoirs of nitrogen predate the comet formation stage or are posterior to it. another central question is elucidating the processes t... | multiple nitrogen reservoirs in a protoplanetary disk at the epoch of comet and giant planet formation |
charge exchange x-ray emission provides unique insight into the interactions between cold and hot astrophysical plasmas. besides its own profound science, this emission is also technically crucial to all observations in the x-ray band, since charge exchange with the solar wind often contributes a significant foreground... | plasma code for astrophysical charge exchange emission at x-ray wavelengths |
organic matter and hydrous silicates are intimately mixed in the matrix of chondrites and in-situ determination of their individual d/h ratios is therefore challenging. nevertheless, the d/h ratio of each pure component in this mixture should yield a comprehensible signature of the origin and evolution of water and org... | micron-scale d/h heterogeneity in chondrite matrices: a signature of the pristine solar system water? |
we present a summary of the campaign of remote observations that supported the european space agency's rosetta mission. telescopes across the globe (and in space) followed comet 67p/churyumov-gerasimenko from before rosetta's arrival until nearly the end of the mission in september 2016. these provided essential data f... | the 67p/churyumov-gerasimenko observation campaign in support of the rosetta mission |
explaining the unexpected presence of dune-like patterns at the surface of the comet 67p/churyumov-gerasimenko requires conceptual and quantitative advances in the understanding of surface and outgassing processes. we show here that vapor flow emitted by the comet around its perihelion spreads laterally in a surface la... | giant ripples on comet 67p/churyumov-gerasimenko sculpted by sunset thermal wind |
we present and compare measurements of the spacecraft potential (vs/c) of the rosetta spacecraft throughout its stay in the inner coma of comet 67p/churyumov-gerasimenko, by the rosetta plasma consortium-langmuir probe (rpc-lap) and ion composition analyzer (rpc-ica) instruments. vs/c has mainly been negative, driven b... | measurements of the electrostatic potential of rosetta at comet 67p |
context. cyanopolyynes are chains of carbon atoms with an atom of hydrogen and a cn group on either side. they are detected almost everywhere in the interstellar medium (ism), as well as in comets. in the past, they have been used to constrain the age of some molecular clouds, since their abundance is predicted to be a... | history of the solar-type protostar iras 16293-2422 as told by the cyanopolyynes |
mercury is embedded in a tenuous and highly anisotropic sodium exosphere, generated mainly by plasma-surface interactions. the absolute values of the sodium ion density are still under debate. observations by messenger's fast imaging plasma spectrometer (fips) instrument suggest the density of exospheric ions to be sev... | influence of mercury's exosphere on the structure of the magnetosphere |
context. measurements of isotopic abundances in cometary ices are key to understanding and reconstructing the history and origin of material in the solar system. comets are considered the most pristine material in the solar system. isotopic fractionation (enrichment of an isotope in a molecule compared to the initial a... | isotopic composition of co2 in the coma of 67p/churyumov-gerasimenko measured with rosina/dfms |
on the 12th of november 2014, the rosetta lander philae became the first spacecraft to softly land on a comet nucleus. due to the double failure of the cold gas hold-down thruster and the anchoring harpoons that should have fixed philae to the surface, it spent approximately two hours bouncing over the comet surface to... | rosetta lander philae: flight dynamics analyses for landing site selection and post-landing operations |
the carbon dimer, the 12c2 molecule, is ubiquitous in astronomical environments. experimental-quality rovibronic energy levels are reported for 12c2, based on rovibronic transitions measured for and among its singlet, triplet, and quintet electronic states, reported in 42 publications. the determination utilizes the me... | experimental energy levels and partition function of the 12c2 molecule |
recent in-situ studies of the environment of comet 67p/churyumov-gerasimenko by the dust instruments onboard the rosetta spacecraft have indicated a complex structure of cometary dust particles. the majority of those particles appeared to be large aggregates of hierarchical structure, i.e. aggregates of particles, whic... | light scattering by hierarchical aggregates |
vacuum-uv (vuv) photodesorption from water-rich ice mantles coating interstellar grains is known to play an important role in the gas-to-ice ratio in star- and planet-forming regions. quantitative photodesorption yields from water ice are crucial for astrochemical models. we aim to provide the first quantitative photon... | vacuum-uv photodesorption from compact amorphous solid water: photon energy dependence, isotopic and temperature effects |
the surface and subsurface of comets preserve material from the formation of the solar system. the properties of cometary material thus provide insight into the physical and chemical conditions during their formation. we present mass spectra taken by the ptolemy instrument 20 minutes after the initial touchdown of the ... | cho-bearing organic compounds at the surface of 67p/churyumov-gerasimenko revealed by ptolemy |
we analytically discuss wave excitation in a homogeneous three component plasma consisting of solar wind protons, electrons and a beam of cometary water ions applied to the plasma environment of comet 67p/churyumov-gerasimenko. the resulting dispersion relations are studied in a solar wind rest frame, where a cometary ... | modified ion-weibel instability as a possible source of wave activity at comet 67p/churyumov-gerasimenko |
water ice-rich patches have been detected on the surface of comet 67p/churyumov-gerasimenko by the virtis (visible infrared and thermal imaging spectrometer) hyperspectral imager on board the rosetta spacecraft, since the orbital insertion in late 2014 august. among these, three icy patches have been selected, and virt... | the temporal evolution of exposed water ice-rich areas on the surface of 67p/churyumov-gerasimenko: spectral analysis |
orbital evolution of binary systems in dense stellar clusters is important in a variety of contexts: origin of blue stragglers, progenitors of compact object mergers, millisecond pulsars, and so on. here we consider the general problem of secular evolution of the orbital elements of a binary system driven by the smooth... | secular dynamics of binaries in stellar clusters - i. general formulation and dependence on cluster potential |
we present the first results from the hst archival legacy project "skysurf." as described in windhorst et al., skysurf utilizes the large hst archive to study the diffuse uv, optical, and near-ir backgrounds and foregrounds in detail. here, we utilize skysurf's first sky-surface-brightness measurements to constrain the... | skysurf: constraints on zodiacal light and extragalactic background light through panchromatic hst all-sky surface-brightness measurements: ii. first limits on diffuse light at 1.25, 1.4, and 1.6 μm |
context. deuteration is a crucial tool for understanding the complexity of interstellar chemical processes, especially when they involve the interplay of gas-phase and grain-surface chemistry. in the case of multiple deuteration, comparing observation with the results of chemical modelling is particularly effective to ... | h2cs deuteration maps towards the pre-stellar core l1544 |
this work presents numerical simulations of meteoroid streams released by comet 21p/giacobini-zinner over the period 1850-2030. the initial methodology, based on vaubaillon et al. (2005), has been updated and modified to account for the evolution of the comet's dust production along its orbit. the peak time, intensity,... | meteor shower modeling: past and future draconid outbursts |
on 29 november 2011 ut, 2060 chiron occulted a r = 14.9-mag star; data were successfully obtained at the 3-m nasa infrared telescope facility (irtf) on mauna kea and 2-m las cumbres observatory global telescope network (lcogt) faulkes telescope north (ftn) at haleakala. the moris lightcurve shows a solid-body detection... | 29 november 2011 stellar occultation by 2060 chiron: symmetric jet-like features |
in this theoretical investigation, we have examined the combined effects of nonthermally modified polarization force on modulational instability of dust acoustic ($da$) waves and evolution of different kinds of rogue waves in space dusty plasma containing negatively charged dust as fluid, boltzmannian electrons and ion... | breather structures and peregrine solitons in a polarized space dusty plasma |
cometary outgassing can produce torques that change the spin state of the cometary nucleus, which in turn influences the evolution and lifetime of the comet. if these torques increase the rate of rotation to the extent that centripetal forces exceed the material strength of the nucleus, the comet can fragment. torques ... | a rapid decrease in the rotation rate of comet 41p/tuttle-giacobini-kresák |
2i/borisov is the first interstellar comet discovered on 2019 august 30, and it soon showed a coma and a dust tail. this study reports the results of images obtained at the telescopio nazionale galileo telescope, on la palma - canary islands, in 2019 november and december. the images have been obtained with the r filte... | dust environment model of the interstellar comet 2i/borisov |
we present high spatial resolution images of the binary transneptunian object gǃkúnǁ'hòmdímà (229762 2007 uk126) obtained with the hubble space telescope and with the keck observatory on mauna kea to determine the orbit of gǃò'é ǃhúgǃò'é ǃhú, the much smaller and redder satellite. gǃò'é ǃhú orbits in a prograde sense, ... | the mutual orbit, mass, and density of transneptunian binary gǃkúnǁ'hòmdímà (229762 2007 uk126) |
centaurs are minor planets thought to have originated in the outer solar system region known as the kuiper belt. active centaurs enigmatically display comet-like features (e.g., tails, comae) even though they orbit in the gas giant region where it is too cold for water to readily sublimate. only 18 active centaurs have... | cometary activity discovered on a distant centaur: a nonaqueous sublimation mechanism |
the kepler-field star kic 8462852, an otherwise apparently ordinary f3 main-sequence star, showed several highly unusual dimming events of variable depth and duration. adding to the mystery was the discovery that kic 8462852 faded by 14 per cent from 1890 to 1989, as well as by another 3 per cent over the 4 yr kepler m... | secular dimming of kic 8462852 following its consumption of a planet |
the origin of the broad emission line region (belr) in quasars and active galactic nuclei is still unclear. i propose that condensations form in the warm, radiation-pressure-driven, accretion disk wind of quasars creating the bel clouds and uniting them with the other two manifestations of cool (∼104 k) gas in quasars,... | quasar rain: the broad emission line region as condensations in the warm accretion disk wind |
in this paper we discuss in a thermodynamic, geologically empirical way the long-term nature of the stable majority ices that could be present in kuiper belt object (kbo) 2014 mu69 (also called arrokoth; hereafter "mu69") after its 4.6 gyr residence in the edgeworth-kuiper belt (ekb) as a cold classical object. we comp... | on the origin & thermal stability of arrokoth's and pluto's ices |
the distant long-period comet c/2017 k2 (panstarrs) has been outside the planetary region of the solar system for ∼3 myr, negating the possibility that heat retained from the previous perihelion could be responsible for its activity. this inbound comet is also too cold for water ice to sublimate and too cold for amorph... | distant comet c/2017 k2 and the cohesion bottleneck |
we here study the transfer process of material from one hemisphere to the other (deposition of airfall material) on an active comet nucleus, specifically 67p/churyumov-gerasimenko. our goals are to: 1) quantify the thickness of the airfall debris layers and how it depends on the location of the target area, 2) determin... | airfall on comet 67p/churyumov-gerasimenko |
here, we show that the detection of borisov implies that interstellar objects outnumber solar system objects in the oort cloud, whereas the reverse is true near the sun due to the stronger gravitational focusing of bound objects. this hypothesis can be tested with stellar occultation surveys of the oort cloud. furtherm... | interstellar objects outnumber solar system objects in the oort cloud |
context. the nitrogen reservoir in planetary systems is a long-standing problem. some of the n-bearing molecules are probably incorporated into the ice bulk during the cold phases of the stellar evolution, and may be gradually released into the gas phase when the ice is heated, for example in active comets. the chemica... | ammonia snow lines and ammonium salts desorption |
the bow shock is the first boundary the solar wind encounters as it approaches planets or comets. the rosetta spacecraft was able to observe the formation of a bow shock by following comet 67p/churyumov-gerasimenko toward the sun, through perihelion, and back outward again. the spacecraft crossed the newly formed bow s... | the infant bow shock: a new frontier at a weak activity comet |
average flow patterns of ions around comet 67p detected by the rpc-ica instrument onboard rosetta are presented both as a time series and as a spatial distribution of the average flow in the plane perpendicular to the comet - sun direction (y-z plane in the coordinate systems used). cometary ions in the energy range up... | average cometary ion flow pattern in the vicinity of comet 67p from moment data |
context. the first long-term in-situ observation of the plasma environment in the vicinity of a comet, as provided by the european rosetta spacecraft.aims: here we offer characterisation of the solar wind flow near 67p/churyumov-gerasimenko (67p) and its long term evolution during low nucleus activity. we also aim to q... | mass-loading of the solar wind at 67p/churyumov-gerasimenko. observations and modelling |
we report photometric observations of comet 29p/schwassmann-wachmann 1 made on august 12, 2016 with the broad-band b, v, r and i filters and the soar 4.1-meter telescope (chile). we find the comet active at that time. enhanced images obtained in all filters reveal three radial features in the 29p/schwassmann-wachmann 1... | comet 29p/schwassmann-wachmann 1 dust environment from photometric observation at the soar telescope |
the nature of the icy material accreted by comets during their formation in the outer regions of the protosolar nebula (psn) is a major open question in planetary science. some scenarios of comet formation predict that these bodies agglomerated from crystalline ices condensed in the psn. concurrently, alternative scena... | a protosolar nebula origin for the ices agglomerated by comet 67p/churyumov-gerasimenko |
recent observations of the long period comet c/2016 r2 (panstarrs) 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 h2o, compared ... | cold traps of hypervolatiles in the protosolar nebula at the origin of comet c/2016 r2 (panstarrs)'s peculiar composition |
the comet database search software was initially released as an open source project in late 2012. prior to that, comet existed as the university of washington's academic version of the sequest database search tool. despite its availability and widespread use over the years, some details about its implementation have no... | a deeper look into comet—implementation and features |
we present post-perihelion photometric and polarimetric observations of comet 67p/churyumov-gerasimenko performed at the 6-m telescope of the sao ras in the g-sdss (465/65 nm), r-sdss (620/60 nm) and r filters. observations in november and december 2015 and april 2016 covered the range of heliocentric distance 1.62-2.7... | spatial variations of brightness, colour and polarization of dust in comet 67p/churyumov-gerasimenko |
modulation instability (mi) and characteristics of dust-acoustic rogue waves (darws) are theoretically investigated in electron-depleted dusty magnetoplasmas comprised of massive dust grains of opposite polarities and nonextensive ions by considering a three-dimensional geometry. for this purpose, the (3 + 1)-dimension... | multidimensional dust-acoustic rogue waves in electron-depleted complex magnetoplasmas |
we present rosetta observations from comet 67p/churyumov-gerasimenko during the impact of a coronal mass ejection (cme). the cme impacted on 2015 oct 5-6, when rosetta was about 800 km from the comet nucleus, and 1.4 au from the sun. upon impact, the plasma environment is compressed to the level that solar wind ions, n... | cme impact on comet 67p/churyumov-gerasimenko |
we observed comet c/2016 r2 (panstarrs) with the aro 10 m smt and report the first detection of co emission from this comet with amounts high enough to be the primary driver of activity. we obtained spectra and maps of the co j = 2-1 rotational line at 230 ghz between 2017 december and 2018 january. we calculated an av... | c/2016 r2 (panstarrs): a comet rich in co and depleted in hcn |
exocomets scattered by planets have been invoked to explain observations in multiple contexts, including the frequently found near- and mid-infrared excess around nearby stars arising from exozodiacal dust. here we investigate how the process of inward scattering of comets originating in an outer belt is affected by th... | scattering of exocomets by a planet chain: exozodi levels and the delivery of cometary material to inner planets |
we perform a thermo-physical analysis on water activity of comet 67p/churyumov-gerasimenko (67p). the sublimation of water is assumed to occur from beneath a global, desiccated dust mantle over the irregular-shaped nucleus. the concept of two thermal models, the recipe of model formulation and the strategy of applicati... | thermal modelling of water activity on comet 67p/churyumov-gerasimenko with global dust mantle and plural dust-to-ice ratio |
we use data on extreme radio scintillation to demonstrate that this phenomenon is associated with hot stars in the solar neighborhood. the ionized gas responsible for the scattering is found at distances up to 1.75 {pc} from the host star, and on average must comprise ∼105 distinct structures per star. we detect azimut... | extreme radio-wave scattering associated with hot stars |
carbonyl sulfide (ocs) is one of the sulfur-bearing molecules detected in different astronomical environments, including comets. the present-day sulfur chemistry in comets may reveal much about the origin of these ices and their subsequent processing history. cometary sulfur molecules such as h2s, h2cs, so2, so, cs, cs... | carbonyl sulfide (ocs): detections in comets c/2002 t7 (linear), c/2015 er61 (panstarrs), and 21p/giacobini-zinner and stringent upper limits in 46p/wirtanen |
we quantitatively investigate the contribution of large dust particles to the polarimetric response in comets using the light-scattering properties of model agglomerated debris particles. we demonstrate that large, supermicron-sized particles have a decreasing role on the degree of linear polarization at phase angle α ... | on the small contribution of supermicron dust particles to light scattering by comets |
comets can be regarded as active planetary bodies because they display evidence for nearly all fundamental geological processes, which include impact cratering, tectonism, and erosion. comets also display sublimation-driven outgassing, which is comparable to volcanism on larger planetary bodies in that it provides a co... | surface morphology of comets and associated evolutionary processes: a review of rosetta's observations of 67p/churyumov-gerasimenko |
to date, at least three comets—2i/borisov, c/2016 r2 (panstarrs), and c/2009 p1 (garradd)—have been observed to have unusually high co concentrations compared to water. we attempt to explain these observations by modeling the effect of drifting solid (ice and dust) material on the ice compositions in protoplanetary dis... | ice-coated pebble drift as a possible explanation for peculiar cometary co/h2o ratios |
we used the new high spectral resolution cross-dispersed facility spectrograph, ishell, at the nasa infrared telescope facility on maunakea, hi, to observe jupiter-family comet (jfc) 45p/honda-mrkos-pajdušáková. we report water production rates, as well as production rates and abundance ratios relative to h2o, for eigh... | hypervolatiles in a jupiter-family comet: observations of 45p/honda-mrkos-pajdušáková using ishell at the nasa-irtf |
the -ch-nh2 moiety represents the fundamental building block of all proteinogenic amino acids, with the cyclic amino acid proline being a special case (-ch-nh- in proline). exploiting a chemical retrosynthesis, we reveal that methylamine (ch3nh2) and/or ethylamine (ch3ch2nh2) are essential precursors in the formation o... | formation of methylamine and ethylamine in extraterrestrial ices and their role as fundamental building blocks of proteinogenic α-amino acids |
we present a summary of the more than 3000 sungrazing and near-sun comets discovered in coronagraph images returned by the solar and heliospheric observatory (soho), since its launch in december 1995. we address each of the four main populations of objects observed by soho: kreutz (sungrazing) group, meyer group, marsd... | soho comets: 20 years and 3000 objects later |
understanding the cosmogonic record encoded in the parent volatiles stored in cometary nuclei requires investigating whether evolution (thermal or otherwise) has modified the composition of short-period comets during successive perihelion passages. as the most volatile molecules systematically observed in comets, the a... | probing the evolutionary history of comets: an investigation of the hypervolatiles co, ch4, and c2h6 in the jupiter-family comet 21p/giacobini-zinner |
context. in june 2021, the discovery of an unusual comet c/2014 un271 (bernardinelli-bernstein) was announced. its cometary activity beyond the orbit of uranus has also refreshed interest in similar objects, including c/2017 k2 (panstarrs). another peculiarity of these objects is the long interval of positional data, t... | the influence of individual stars on the long-term dynamics of comets c/2014 un271 and c/2017 k2 |
context. class i protostars are a bridge between class 0 protostars (≤105 yr old), and class ii (≥106 yr) protoplanetary disks. recent studies show gaps and rings in the dust distribution of disks younger than 1 myr, suggesting that planet formation may start already at the class i stage. to understand what chemistry p... | chemical survey of class i protostars with the iram-30 m |
earth occasionally crosses the debris streams produced by comets and other active bodies in our solar system. these manifest meteor showers that provide an opportunity to explore these bodies without a need to visit them in-situ. observations of meteor showers provide unique insights into the physical and dynamical pro... | comets and meteor showers |
plasma treatment constitutes an efficient method for chemical-free disinfection. a spray-based system for dispensing plasma-activated aerosols onto surfaces would facilitate disinfection of complex and/or hidden surfaces inaccessible to direct line-of-sight (for example, uv) methods. the complexity and size of current ... | nanoscale plasma-activated aerosol generation for in situ surface pathogen disinfection |
in situ images of the 67p/churyumov-gerasimenko nucleus acquired by the civa cameras on-board philae revealed a rough landscape dominated by consolidated materials. these data provide a unique view to constrain the past and present conditions prevailing at the surface of the comet. a quantitative analysis of microscopi... | origin of the local structures at the philae landing site and possible implications on the formation and evolution of 67p/churyumov-gerasimenko |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.