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rolling bearings are universally adopted to serve as revolute joints in almost all mechanisms or machines, because they offer a convenient solution to the problem of minimizing friction and, simultaneously, providing a large load-carrying capacity at any kinematic regime, including slow or alternate rotations. however,... | an accelerated test stand to assess wear in offshore wind turbines rolling bearings |
it has long been the view that energetic charged particle radiation can darken ice. recent work on the inner saturnian satellites links levels of mev electron and proton bombardment with global brightness (hedman et al. 2020). at saturn, the subject lends itself to careful analysis as inner satellites like janus and mi... | weathering of ice on the jovian and saturnian satellites |
a surprisingly strong influx of organic-rich material into saturn's upper atmosphere from its rings was observed during the proximal obits of the grand finale of the cassini mission. measurements by the ion and neutral mass spectrometer (inms) gave insights into the composition of the material, but it remains to be res... | utilizing helium ion chemistry to derive mixing ratios of heavier neutral species in saturn's equatorial ionosphere |
planetary spin can inform our understanding of planet accretion histories, which determine final masses and atmospheric compositions, as well as the formation of moons and rings. at present, the physics behind how gas giant planets spin up is still very poorly understood. we know that when giant planets form, they accr... | the world is spinning: constraining the origin of supermassive gas giant planets at wide separations using planetary spin |
recent measurements of jupiter's gravitational moments by the juno spacecraft and seismology of saturn's rings suggest that the primordial composition gradients in the deep interior of these planets have persisted since their formation. one possible explanation is the presence of a double-diffusive staircase below the ... | rotation reduces convective mixing in jupiter and other cold gas giants |
the cassini-huygens mission ended in a science-rich blaze of glory on september 15, 2017. covering a period of roughly ten months, the grand finale and ring grazing orbits marked the final phases of cassini's 13-year mission, ending with the first time in-situ exploration of the region between the rings and planet. on ... | cassini's grand finale: discoveries and highlights one year later |
"purest anorthosite" (pan) are rocks of the lunar primary crust with over 98 vol% plagioclase. understanding the distribution and purity of pan on a local scale can help put constraints on the efficiency of plagioclase separation from the lunar magma ocean and help to illuminate the makeup of the moon's primary crust. ... | investigating local variations of lunar rock types at sites of "purest anorthosite" detection |
ductile and brittle deformation reshapes our planet as a consequence of plate tectonics. while the relative age of these processes can be inferred with field and petrographic relationships, absolute timing of these multiphase processes is usually unclear. most attempts to directly date these events have failed because ... | timing and duration of brittle deformational events. laser u-pb ssi ages on calcite (al hajar mountains, oman) |
the dawn spacecraft has been orbiting dwarf planet ceres since march 2015. images from the dawn's framing camera (fc) have been used to create shape models of ceres using stereophotogrammetry [1] and stereophotoclinometry [2,3] techniques. these shape models have since been used for orthorectifcation of the fc images a... | roughness of ceres from high-resolution shape models |
the cosmic facility was developed at nasa ames to study interstellar, circumstellar and planetary analogs in the laboratory [1]. cosmic stands for “cosmic simulation chamber” and is dedicated to the study of neutral and ionized molecules and nanoparticles under the low temperature and high vacuum conditions that are re... | advances in interstellar and planetary laboratory astrophysics with ames’ cosmic facility |
today, we believe that the onset of life requires free energy, water, and complex, probably carbon-based chemistry. in the interstellar medium, complex organic molecules seem to mostly form in reactions happening on the icy surface of dust grains, such that they are released into the gas phase when the dust is heated. ... | probing the water and co snow lines in the young protostar ngc 1333-iras4b |
planets form and obtain their compositions in gas-rich disks around young stars. the molecular gas and associated chemistry are directly tied to the resulting exoplanet architectures, including what types of planets form, their atmospheres, and potential habitability. while molecular line observations often provide the... | zooming in on the chemistry of planet formation: the alma view of molecular gas in protoplanetary disks |
in september 2017, the cassini spacecraft entered saturn's atmosphere, providing new insights into the composition and structure of the planet's upper atmosphere. prior to atmospheric entry, cassini executed a series of 22 highly inclined orbits through the previously unexplored region between saturn and its rings, yie... | the composition and thermal structure of saturn's upper atmosphere from cassini/inms measurements |
high precision exoplanet light curves offer the opportunity for detailed characterization far beyond estimating the radius and orbital period of exoplanets and are now able to estimate parameters such as reflectivity and temperature. such details provide information about the planet's composition and potential habitabi... | thermal variations of extremely close-in exoplanets |
observations from the texas echelon cross echelle spectrograph (texes) on nasa"s irtf and the visir instrument on the vlt are used to characterize the saturn"s seasonal changes. radiative transfer modelling (using nemesis [8]) provides the northern hemisphere temperature progression of the atmosphere over 10 years, bot... | saturn's seasonal atmosphere: cassini cirs contrasts to vlt and irtf observations |
a strongly coupled unmagnetized rotating dust ring interacting through a yukawa potential has been observed in a laboratory rf-driven dusty plasma. radial confinement is provided by the plasma potential well that forms above a 70 mm (o.d.) groove with a center pedestal. it is well known that in magnetized plasmas the e... | unmagnetized rotating plasma dust ring |
it is now known that many spiral density waves in saturn's c ring are forced by resonant gravitational interactions with the planet's nonradial oscillations. observations of their periods have the power to reveal new information concerning subtle aspects of the planet's internal structure. the properties of a certain c... | nonradial oscillations of saturn: forcing of the slowest spiral density waves in the c ring by i-modes and r-modes and the implications for the internal structure |
tree rings from europe and north america show reduced growth from ~536 to 555 a.d. if the reduction were solely due to high aerosol optical depth produced by sulfate from explosive volcanic eruptions, ice cores should record intense sulfate deposition ~ every 3 years, the stratospheric residence time of sulfate from on... | what are the sources of 91 low latitude fossils found in the gisp2 ice core and dating from 535 to 542 a.d.? |
the molecular composition, haze abundance, and thermal structure of saturn's upper atmosphere is determined by the solar insolation. as with any planet, the amount of sunlight impinging on the atmosphere is determined by both the planet's distance from the sun in addition to seasonal effects cause by the planet's axial... | photochemistry and heating in saturn's atmosphere: ring shadow and ring reflection |
the saturn system possesses a number of small unique moons, including the coorbitals janus and epimetheus; the ring moons pan and daphnis; and prometheus, pandora, and atlas, which orbit near the edge of the main ring system. during the last phases of the cassini mission, when the spacecraft executed close passes to th... | five fabulous flybys of the small inner moons of saturn by the cassini spacecraft |
the surface of the moon was shaped by large-scale impact basins and 50-60 of such basins are identified with well-preserved morphologies. the formation of impact basins is influenced by target properties and most obviously by the size, composition (mass), and velocity of the impactor. beside the surface expression (cra... | formation of impact basins on the moon - insights from numerical modeling, gravity and remote sensing data |
photosynthesis has dominated the biological carbon cycle for 100s of millions of years. photorespiration, the process by which previously fixed glycine is carboxylated to co2 within the mitochondrion, is fundamental to all photosynthetic organisms and serves to decrease the overall efficiency of photosynthesis. increas... | using tree rings to quantify 100 years of photorespiration decline |
the cassini inms data set gathered during the grand finale phase of the mission provides information about the atmospheric composition that can be used to infer effects in the interior of saturn. the he/h2 ratio measured in the upper atmosphere can be used to infer information about the he/h2 in the well mixed interior... | implications from cassini ion neutral mass spectrometer (inms) grand finale measurements on atmospheric and interior processes at saturn |
titan's lakes and seas are composed of predominantly methane and ethane [1], however thermodynamic modeling suggests that various other molecules exist in the lakes at lower abundances. some of these molecules include: acetylene, ethylene, benzene, and acetonitrile e.g., [2-5]. as the lakes evaporate, they may leave be... | experimental study of evaporites on titan |
we present and discuss the characteristics and the capabilities of the laboratory facility, cosmic, that was developed at nasa ames to generate, process and analyze interstellar, circumstellar and planetary analogs in the laboratory [1]. cosmic stands for “cosmic simulation chamber” and is dedicated to the study of neu... | laboratory astrophysics studies with the cosmic facility: interstellar and planetary applications. |
understanding how astrophysical processes like diffusion, evaporation, and condensation of volatile ices affects the ratios of isotopes can help us better understand observations of isotopic variation in astrophysical systems. for example, the sublimation of water-ice from astrophysical and planetary surfaces such as i... | mulit-isotopic fractionation of water from sublimation at low temperatures |
we show existence of energetic quasi-sunward o+ ion jets (~10 kev or higher) reflected below the martian bow shock by analyzing ion velocity distribution functions (vdfs) measured by the superthermal and thermal ion composition (static) instrument on the mars atmosphere and volatile evolution mission (maven). in the so... | sunward o+ ion jets reflected below the martian bow shock: maven observations |
the cassini-huygens mission ended in a science-rich blaze of glory on september 15, 2017. covering a period of roughly ten months, the grand finale and ring grazing orbits marked the final phases of cassini's 13-year mission, ending with the first time in-situ exploration of the region between the rings and planet. on ... | new discoveries in cassini's grand finale year |
the morphology and composition of star and inner disk also have an impact on the disk structure at larger radii. in fact, the shadows, spirals, rings that have been recurrently imaged at >5 au can be traced back to stellar mass and metallicity as well as to the presence of a misaligned inner belt within a disk cavit... | the outer disk knows about the inner disk |
we study the plasma interactions of galilean satellites by means of multi-species global hybrid simulations. we consider multi-species background plasma composed of oxygen and sulphur ions and multi-component neutral atmospheres. the neutral atmospheres via several ionization processes then represents a source of dense... | global multi-species hybrid modelling of plasma interactions at galilean moons |
for cassini's grand finale, the spacecraft completed 22 orbits that passed between saturn and the d ring from north to south. prior to these orbits, it was expected that the ion neutral mass spectrometer (inms) would observe only h2 and he from saturn's atmosphere. instead, mass surveys early in the grand finale detect... | cassini ion neutral mass spectrometer measurements of d ring influx to saturn's atmosphere |
the floors of large impact structures are largely flat and contain one or more morphological rings. the formation of the innermost topographic ring, the so-called peak ring, and the causes of target rock weakening leading to observed flat crater floors are not well understood. constraining these mechanisms is the prime... | target-rock fluidization during peak-ring formation of the chicxulub crater inferred from expedition 364 drill core |
the innermost narrow ringlet in saturn's ring system is located around 67,630 km from saturn's center and is designated d68. observations of this ringlet early in the cassini mission showed that it was composed primarily of small particles and was roughly the same brightness all the way around the planet. however, imag... | what has been happening to saturn's innermost ringlet? |
seismology has been the premier tool of study for understanding the interior structure of the earth. the sun, and even other stars. in this thesis we develop the framework for the first ever seismic inversion of a rapidly rotating gas giant planet. we extensively test this framework to ensure that the inversions are ro... | seismic inferences of gas giant planets: excitation & interiors |
in the final phase of the cassini mission in 2016-2017, the spacecraft will first move to orbits with periapse outside the f-ring and then to orbits grazing the upper atmosphere of saturn. these trajectories will provide the unique opportunity to sample the structures and composition of saturn's ionosphere but also tho... | ion composition of the thermal plasma in the f-ring region of saturn |
we review the different key findings made by the cassini-huygens spacecraft that allowed to shed light on the formation conditions of saturn, its rings and surrounding satellite system. among them, cassini's measurements of the enceladus' plumes isotopic composition show that this satellite likely agglomerated from bui... | origin of the saturnian system after the cassini-huygens mission |
dawn xm2 high resolution imaging of 92-km diameter occator crater on ceres at better than 10-m pixel scales provides an opportunity to test hypotheses based on earlier lamo mapping at 35 m scales. among these are the origins of the extensive lobate floor deposits (post-impact volcanism or impact "melt"), of bright carb... | occator crater at 35 km altitude: dawn xm2 mapping of a pristine impact basin on a hydrous dwarf planet |
charles beichman (ipac/nasa exoplanet science institute), natalie batalha (nasa ames research center), elodie choquet (jet propulsion laboratory), camilla danielski (observatoire de meudon), andras gaspar (university of arizona), tom greene (nasa ames research center), sasha hinkley (university of exeter), klaus hodapp... | finding and characterizing exoplanets with the james webb space telescope (jwst) |
the cosmic facility was developed at nasa ames to study interstellar, circumstellar and planetary analogs in the laboratory [1, 2]. cosmic stands for “cosmic simulation chamber” and is dedicated to the study of molecules, ions and nanoparticles under the low temperature and high vacuum conditions that are required to s... | nasa ames’ cosmic laboratory astrophysics facility: recent results and progress |
using alma we detect for the first time co gas in a debris disc around a solar-type star. we find the gas is of secondary origin and we probe the co/rock composition of exocomets in the disc, finding it matches with solar system comets. the dust continuum is resolved in an axisymmetric ring that that is consistent with... | alma: exocometary gas in the hd 181327 debris ring |
"snow lines", marking regions where abundant volatiles freeze out onto the surface of dust grains, play an important role for planet growth and bulk composition in protoplanetary disks. however, they can already be observed in the envelopes of the much younger, low-mass class 0 protostars that are still in their early ... | probing the methanol and co snow lines in young protostars |
the cassini radar's altimetry mode has been successfully used for probing the depth and composition of titan's hydrocarbons seas. in may 2013, during the spacecraft's 91stflyby of titan (t91), the instrument demonstrates its capabilities as a radar sounder, presenting a unique opportunity to constrain direct measuremen... | an overview of the bathymetry and composition of titan's hydrocarbon seas from the cassini radar altimeter |
we develop a 2-d io torus physical chemistry model that combines latitudinal and radial variations assuming azimuthal symmetry. we model the distribution along the magnetic field and solve the radial fokker-planck equation to model the radial transport of the plasma out past the orbit of europa. our model includes ioni... | a 2d io plasma torus physical chemistry model and comparisons with remote and in situ observations |
chiron is an active centaur object of radius ~110 km orbiting between saturn and uranus. its size and orbital elements are similar to those of the largest centaur known to date, chariklo (radius~120 km). in 2013, a stellar occultation revealed the surprising presence of two narrow and dense rings around the latter body... | search for material around chiron |
the gemini planet imager (gpi) is a near-infrared imaging instrument used with the gemini south telescope in chile to provide direct imaging and integral field spectroscopy of exoplanetary systems. one of the central goals of the gpi mission is to gain an improved understanding of debris disks, which are remnants of th... | the gemini planet imager view of the hd 32297 debris disk system |
the obliquity, or angular separation between spin and orbit poles, of asteroid (16) psyche is currently 95 degrees. we are interested in knowing how much that angular separation varies, on time scales of 104 to 106 years. to answer that question, we have done several related analyses. on short time scales, the orbital ... | secular orbit and spin variations of asteroid (16) psyche |
v582 mon (kh 15d) is a binary t tauri star, composed of a k1 and k7 star embedded in a circumbinary ring that is inclined to the binary orbit. the age of the stars is 1-3 myr and their total mass is about 1.3 solar masses. physics of the precession indicates that the center of the ring is at about 3.8 au from the cente... | an update on the v582 mon (kh 15d) binary t tauri system |
we present and discuss the characteristics and the capabilities of the laboratory facility, cosmic, that was developed at nasa ames to generate, process and analyze interstellar, circumstellar and planetary analogs in the laboratory [1]. cosmic stands for “cosmic simulation chamber” and is dedicated to the study of neu... | recent progresses in laboratory astrophysics with ames’ cosmic facility |
cassini observations have found that the plasma and magnetic field conditions upstream of titan are far more complex than they were thought to be after the voyager encounter. rymer et al., (2009) used the cassini plasma spectrometer (caps) electron observations to classify the plasma conditions along titan's orbit into... | the effects of upstream plasma properties on titan's ionosphere |
"rbspice in the classroom: changing magnetic fields and electrical currents" is a hands-on exercise for middle school and high school science classrooms. students build a ballistic galvanometer using inexpensive common items that can be purchased at any craft store, and make qualitative observations of changing magneti... | rbspice in the classroom: building a ballistic galvanometer using common household products |
tobias chant owen (toby) was a graduate student of g. p. kuiper, receiving his ph.d. in the dept. of astronomy, university of arizona, in 1965. his thesis was broadly titled "studies of planetary spectra in the photographic infrared", and primarily presented a study of the composition and other properties of jupiter, a... | the early planetary research of tobias c. owen |
evaluating the potential habitability of the icy ocean worlds of the outer planets requires an understanding of three main components, the chemistry and composition of the material making up the body, the sources of chemical disequilibrium available for potential metabolic processes, and the geology that drives the int... | gaining insight into surface geologic processes on europa through geologic mapping at global and regional scales |
planets form out of disks around young stars that are composed of dust and gas. the dust in these disks grows and forms planetesimals that go on to become rocky planets or cores which accrete disk gas, creating giant planets. as planets form, they create a footprint in the shape of ring-like gaps in the protoplanetary ... | multiwavelength characterization of planet formation environments |
the ice giant planets, uranus and neptune, are priority targets for future exploration because they challenge our understanding of how planets form and evolve, unique physical properties are on display in their rings, satellites, and magnetospheres, and because ice giants are common around other stars. nasa and esa rec... | a study on exploring uranus and neptune: science objectives and mission requirements |
the lower mantle makes up more than a half of our planet's volume. mineralogical and petrological experiments on realistic bulk compositions under high pressure-temperature (p-t) conditions are essential for understanding deep mantle processes. such high p-t experiments are commonly conducted in a laser-heated diamond ... | development of high-pressure multigrain x-ray diffraction forexploring the earth's interior |
the historic encounters of the new horizons spacecraft with the pluto system in 2015 and arrokoth in 2019 have yielded a wealth of new information about the physical and chemical makeup of these remarkably diverse members of the kuiper belt. i review the properties of both systems and examine their formation within the... | a unified model for the formation of bi-lobate arrokoth and the pluto-charon binary |
analyses of data from cassini's ion and neutral mass spectrometer (inms) taken during several close flybys of enceladus suggest the presence of a potentially habitable ocean underneath the ice shell [1,2]. proper identification of the molecular species sampled from enceladus' plumes by inms is of utmost importance for ... | quantitative chemical analysis of enceladus' plume composition. |
the deep geological and geophysical studies of the continents and oceans have revealed a number of well-defined new regularities in the structure of the crust and upper mantle that do not find a clear explanation in the modern geodynamic concepts. - the earth is divided into two hemispheres with different structure of ... | unsolved problems of the global tectonics and a possibility of their solution |
we describe the discovery of a bright, young kuiper belt-like debris disk around hd 115600, a ∼ 1.4--1.5 m_{⊙}, ∼ 15 myr old member of the sco-cen ob association. our h-band coronagraphy/integral field spectroscopy from the gemini planet imager shows the ring has a (luminosity scaled) semi major axis of (∼ 22 au) ∼ 48 ... | extreme exoplanet direct imaging: new results with gpi and scexao and the path to imaging another earth |
the new horizons flyby of mu69 has yielded a wealth of new data on the physical structure and surface chemistry of this cold classical kbo (cckbo). one surprising discovery is the flattened shape of each lobe. another is the low spin rate. this means that the lobes must have lost orbital angular momentum, prior to merg... | can the sublimation of dry ice explain the flattened, bilobate structure and spin rate of 2014 mu69 |
the origin and evolution of saturn's rings is critical to understanding the saturnian system as a whole. here, we discuss the physical and chemical composition of the rings, as a foundation for evolutionary models described in subsequent chapters. we review the physical characteristics of the main rings, and summarize ... | the composition of saturn's rings |
extreme adaptive optics instruments have revealed exquisite details on debris discs, allowing to extract the optical properties of the dust particles such as the phase function, the degree of polarisation and the spectral reflectance. these are three powerful diagnostic tools to understand the physical properties of th... | insight from laboratory measurements on dust in debris discs |
the kepler-51 system consists of three known "super-puff" exoplanets - ultra-low density objects that challenge current theories of planet formation and evolution, with masses measured exclusively from transit timing variations (ttvs). the transmission spectra of kepler-51b and d were observed with jwst to investigate ... | the discovery of a fourth low-mass planet in an unusual super-puff system |
we use a three-dimensional hybrid plasma model to study the global aspects of jovian plasma interaction with ganymede. ganymede, the largest moon of jupiter, is a unique body for several reasons: (1) it is the only known moon that has its own intrinsic magnetic field, (2) its dipole magnetic moment is large enough to f... | jovian plasma interaction with ganymede's magnetosphere |
uranus and saturn share similarities in terms of their atmospheric composition, which is primarily made up of hydrogen and helium, as well as their ring systems. uranus has 13 known rings, which are divided into narrow main rings, dusty rings, and outer rings. unlike saturn's broad ring system, uranus' inner narrow mai... | infalling of nano-dust because of air drag on uranus |
context. t tauri stars are low-mass young stars whose disks provide the setting for planet formation, which is one of the most fundamental processes in astronomy. yet the mechanisms of this are still poorly understood. su aurigae is a widely studied t tauri star and here we present original state-of-the-art interferome... | imaging the warped dusty disk wind environment of su aurigae with mirc-x |
alkaline-carbonatite complexes are a primary resource for rees and act as efficient sequesters of deep carbon, however their origin and structure remains widely debated and poorly understood. the arkansas alkaline province, an area of northeast trending igneous intrusions of lamproites, diamond-bearing kimberlites, and... | structural interpretation of an alkaline-carbonatite complex at magnet cove, arkansas using gravity and magnetic methods |
exo-planets are common, and they span a large range of compositions. the origins of the observed diversity of planetary compositions is largely unconstrained, but must be linked to the planet formation physics and chemistry. among planets that are earth-like, a second question is how often such planets form hospitable ... | the chemistry of planet formation |
the ζ ring is the innermost component of the uranian ring system. it is of scientific interest because its morphology changed significantly between the voyager 2 encounter in 1986 and subsequent earth-based observations around 2007. it is also of practical interest because some uranus mission concepts have the spacecra... | examining uranus' ζ ring in voyager 2 wide-angle camera observations: quantifying the ring's structure in 1986 and its modifications prior to the year 2007 |
the gas-and dust rich disks that surround all young solar type stars are characterised by holes, gaps, rings and warps, that are believed to be signposts of on-going planet formation. exoplanet surveys show a remarkable diversity in exoplanet properties, and in exoplanetary system architectures. what are the processes ... | planet forming disks: the promise of jwst, and science cases for a next generation ir facility |
a stellar occultation of gaia dr3 2646598228351156352 by the centaur (2060) chiron was observed from the south african astronomical observatory on 2018 november 28 ut. here we present a positive detection of material surrounding chiron from the 74-inch telescope for this event. additionally, a global atmosphere is rule... | material around the centaur (2060) chiron from the 2018 november 28 ut stellar occultation |
io's intense volcanic activity results in one of the most colorful surfaces in the solar system. ultraviolet and visible-wavelength observations of io are critical to uncovering the chemistry behind its volcanic hues. here, we present global, spatially resolved ultraviolet-visible spectra of io from the space telescope... | spectroscopic mapping of io's surface with hst/stis: so2 frost, sulfur allotropes, and large-scale compositional patterns |
we report the first near-infrared detection of uranus's tiny moon mab, the presumed source of the blue and diffuse μ ring, using the nirc2 instrument at keck observatory. the detection was permitted by an updated shift-and-stack procedure allowing us to integrate on mab as it moved across the detector in 23 separate ex... | keck near-infrared detections of mab and perdita |
we present the fuv phase curves of saturn's rings as a function of radius relative to the center of the planet, for both the lit and unlit side of the rings. this updated analysis expands on our previous work (elliott and esposito 2021, dps) by examining the phase curves of the rings at a finer granularity. each of the... | cassini uvis fuv phase curve maps and the age of saturn's rings as a function of radius |
in the last five years alma revolutionised our comprehension of planet formation. the first breakthrough was delivered by the impacting image of the rings in the disk of hl tau, suggesting that planet formation occurs early, in disks of less than 1 myr. alma is revolutionising also our comprehension of the disk chemist... | alma-dot: the alma chemical survey of disk-outflow sources in taurus |
planetary organic hazes can play a significant role in influencing a planet's radiative balance and climate, with their impact determined by the optical properties of the haze. the optical properties, in turn, are partly influenced by particle composition. our previous work, reed et al., demonstrated that trace amounts... | the influence of hydrogen sulfide on the optical properties of planetary organic hazes: implications for exoplanet climate modeling |
earth's space environment system is comprised of a myriad of plasma populations. these populations encompass characteristic energies ranging over 6 orders of magnitude; from sub-ev plasma in the ionosphere, to 10-100 kev plasma in the ring current, and mev and higher particles in the radiation belts. further complicati... | global modeling of the drivers and impacts of storm-time plasma composition |
scientists have long believed that there may be billions to trillions of rogue planets drifting through our galaxy, unattached to any host star. a recent study has now identified one such candidate potentially the first terrestrial-mass world weve spotted on the run.severing attachmentsartists impression of a free-floa... | a terrestrial-mass planet on the run? |
the role of the pre-solar chemistry in the chemical composition of solar system bodies is far to be understood. did they inherit at least part of their composition from the earliest stages of star formation? during each step of the process leading to the formation of a sun-like star and its planetary system, the molecu... | complex organics in protostellar disks: the first stage of a long chemical journey to planetary systems |
duo to the large magnetic reynolds number, the magnetic helicity originating from the solar interior can be carried away through the photosphere into the corona. however, the relationship between the accumulated magnetic helicity flux through the photosphere and the magnetic helicity in the corona is still unclear. by ... | comparison of two methods for calculating magnetic helicity in the solar corona |
polar faculae are the footpoints of magnetic-field lines near the sun's poles that are seen as bright regions along the edges of granules. the time variation in the number of polar faculae has been shown to correlate with the strength of the polar magnetic field and to be a predictor of the subsequent solar cycle. due ... | two new methods for counting and tracking the evolution of polar faculae |
we study the relation between stellar dynamo-wave propagation and the structure of the stellar magnetic field. modeling dynamo waves by the well-known parker migratory dynamo, we vary the intensity of dynamo drivers in order to obtain activity-wave propagation toward the equator (as in the solar-activity cycle) or towa... | migrating dynamo waves and consequences for stellar current sheets |
we are conducting a comprehensive investigation of v815 her using photometric and spectroscopic data to understand the origin of the activity and what influences it in the short and long term. using tess photometry we performed light curve modeling in order to derive astrophysical and orbital parameters for the eclipsi... | a star under multiple influences. magnetic activity in v815 her, a compact 2+2 hierarchical system |
the ubiquitousness of solar inter-network horizontal magnetic field has been revealed by the space-borne observations with high spatial resolution and polarization sensitivity. however, no consensus has been achieved on the origin of the horizontal field among solar physicists. for a better understanding, in this study... | does the variation of solar inter-network horizontal field follow sunspot cycle? |
the sunspot number record covers over three centuries.these numbers measure the activity of the sun. this activity follows the solar cycle of about eleven years. in the dynamo-theory, the interaction between differential rotation and convection produces the solar magnetic field. on the surface of sun, this field concen... | sunspot cycles are connected to the earth and jupiter |
exoplanet hunting surveys, including kepler and k2, have begun a new era for stellar magnetic activity studies, particularly for white light flares. continuous light curves with months to years baselines, and unmatched photometric precision, has led to discoveries including "superflares" on solar-type stars, the evolut... | combining kepler and tess: 10 years of stellar flare studies from space |
we present the results of our observations of the maser radio emission source g188.946+0.886 in hydroxyl (oh) molecular lines with the radio telescope of the nançay observatory (france) and in the h2o line at λ = 1.35 cm with the rt-22 radio telescope at the pushchino observatory (russia). an emission feature in the 17... | investigation of oh and h2o masers in the star-forming region g 188.946+0.886 |
ground level enhancements (gles) are extreme solar energetic particle (sep) events that are of particular importance in space weather. in solar cycle 24, two gles were recorded on 2012 may 17 (gle 71) and 2017 september 10 (gle 72), respectively, using a range of advanced modern instruments. here we conduct a comparati... | effects of coronal magnetic field configuration on particle acceleration and release during the ground level enhancement events in solar cycle 24 |
the 2021 extreme precision radial velocity (eprv) working group's report, and the more recent 2022 sag21 findings, emphasizes that stellar activity is a primary hurdle to confirming and characterizing earth analogs (earth mass planets orbiting in the habitable zones of sun-like stars). as such, scientific interest has ... | starspot: a space-based spectrophotometric platform for stellar activity characterization |
in this study, new photometric observations of shallow contact binary cn andromedae (cn and) were performed and multi-color (bv r) ccd light curves (lcs) were obtained. simultaneous analysis of new lcs and published radial velocity (rv) data reveals that the system is an early contact binary in which both components ha... | cn andromedae: a shallow contact binary with a possible tertiary component |
the sun is a g2v star with an effective temperature of 5780 k. as the nearest star to earth and the biggest object in the solar system, it serves as a reference for fundamental astronomical parameters such as stellar mass, luminosity, and elemental abundances. it also serves as a plasma physics laboratory. a great deal... | solar photosphere |
the existence of magnetic activity on the eclipsing binary dv psc has been known for almost two decades. however, until recently, no evidence of periodic behaviour relevant to this activity had been found. in this study, long-term photometric observations of dv psc are used to analyze the system's magnetic activity, se... | temporal evolution of the magnetically active eclipsing binary dv psc |
surface acoustic waves (saws) propagate along material surfaces or at solid-air, solid-liquid, solid-solid, and solid-vacuum interfaces. saws are confined to surfaces within the depth of one wavelength, and the saw velocity depends on the elastic properties of the material. hence saws can be used to determine thermomec... | probing thermomechanical properties of two-dimensional van der waals architectures using surface acoustic waves |
miura-ori pattern is seen in nature be it the unfolding of a leaf or opening and closing of insect wings. similar patterns in the form of wrinkles and ridges are also observed in biaxially compressed rigid thin films supported on soft substrates. we have investigated the formation of wrinkles and ridges in graphene pla... | dynamics of wrinkle-ridge transition in graphene supported on a polymer: quantum molecular dynamics simulations |
photodissociation studies in molecular beams that employ position-sensitive particle detection to map product recoil velocities emerged thirty years ago and continue to evolve with new laser and detector technologies. these powerful methods allow application of tunable laser detection of single product quantum states, ... | invited review article: photofragment imaging |
context. one of the main challenges for polarimetric observations of active galactic nuclei (agn) is to properly estimate the amount of parasitic light that contaminates the polarization signal. removing this unpolarized flux is a complex task that has only been achieved in a couple of objects.aims: in this fifth paper... | modeling optical and uv polarization of agns. v. dilution by interstellar polarization and the host galaxy |
the origin of terrestrial bioorganic homochirality is one of the most important and unresolved problems in the study of chemical evolution prior to the origin of terrestrial life. one hypothesis advocated in the context of astrobiology is that polarized quantum radiation in space, such as circularly polarized photons o... | origin of terrestrial bioorganic homochirality and symmetry breaking in the universe |
linear polarization has been measured in several gamma-ray burst (grb) afterglows. after a few days, polarization arises from the forward shock emission that depends on the post-shock magnetic field. the latter can originate both from compression of existing fields, here the interstellar medium (ism) magnetic field, an... | impact of the ism magnetic field on grb afterglow polarization |
magnetic fields are crucial in numerous astrophysical processes within the interstellar medium (ism). however, the detailed determination of magnetic field geometry is notoriously challenging. based on the modern magnetohydrodynamic (mhd) turbulence theory, we introduce a novel statistical technique, the 'y-parameter',... | diagnosis of 3d magnetic field and mode composition in mhd turbulence with y-parameter |
aims: the optical emission of black hole transients increases by several magnitudes during the x-ray outbursts. whether the extra light arises from the x-ray heated outer disc, from the inner hot accretion flow, or from the jet is currently debated. optical polarisation measurements are able to distinguish the relative... | evolving optical polarisation of the black hole x-ray binary maxi j1820+070 |
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