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this book describes selected problems in contemporary spectroscopy in the context of quantum mechanics and statistical physics. it focuses on elementary radiative processes involving atomic particles (atoms, molecules, ions), which include radiative transitions between discrete atomic states, the photoionization of ato... | atomic and molecular radiative processes: with applications to modern spectroscopy and the greenhouse effect |
the thermal radio and submillimetre (sub-mm) emission from the winds of massive stars is investigated and the contribution to the emission due to the stellar wind acceleration region and clumping of the wind is quantified. building upon established theory, a method for calculating the thermal radio and sub-mm emission ... | submillimetre free-free emission from the winds of massive stars in the age of atacama large millimeter/submillimeter array |
the first solar radio line attributed to atomic hydrogen was theoretically grounded by j.p. wild in 1952. its zeeman profile was calculated and reliably established in the radiation from quiet sun regions and activity features over sunspots in 2018 using observations with the ratan-600 radio telescope, leading to the d... | the possibility of observing several hydrogen radio lines in solar activity features over sunspots |
a new foe model for the auroral region is constructed; the model is based on an analysis of the models of auroral electron precipitations, the boundaries of the discrete and diffusive aurora, the main ionospheric trough, and measurements of the e-layer critical frequency foe. the model is an analytical model. it consis... | model of the e-layer critical frequency for the auroral region |
lightning discharges and radio transmitters emit low-frequency (∼3-300 khz) electromagnetic waves with large electric field strengths and stable phases. this phase stability makes it possible to map the source locations of lightning and transmitters in the sky. electromagnetic waves with smaller electric field strength... | first map of coherent low-frequency continuum radiation in the sky |
we analyze the physical conditions in the source region of a zebra structure, observed with the ondřejov radiospectrograph during the 1 august 2010 solar flare. to determine the gyro-frequency harmonic numbers of the observed zebra lines, we compute the magnetic field strength, the electron density, and their spatial s... | physical conditions in the source region of a zebra structure |
we present a polarization study towards the supernova remnant (snr) puppis a based on original observations performed with the australia telescope compact array. based on the analysis of a feature detected outside the snr shell (called `the tail' throughout the paper), it was possible to disentangle the emission with o... | new perspectives on the supernova remnant puppis a based on a radio polarization study |
we report new 5.5 ghz radio observations of the massive star cluster westerlund 1, taken by the australia telescope compact array, detecting nine of the ten yellow hypergiants (yhgs) and red supergiants (rsgs) within the cluster. eight of nine sources are spatially resolved. the nebulae associated with the yhgs wd1-4a,... | asymmetric ejecta of cool supergiants and hypergiants in the massive cluster westerlund 1 |
a search of the first data release of the vista variables in the via lactea (vvv) survey discovered the exceptionally red transient vvv-wit-01 (h - ks = 5.2). it peaked before march 2010, then faded by ∼9.5 mag over the following 2 yr. the 1.6-22 μm spectral energy distribution in march 2010 was well fit by a highly ob... | vvv-wit-01: highly obscured classical nova or protostellar collision? |
in this paper we give the first attempt to model the evolution of the spectrum of psr b1259-63 radio emission while the pulsar orbits the companion be star. as suggested by kijak et al. (mon. not. r. astron. soc. 418:l114, 2011a) this binary system can be useful in understanding the origin of the gigahertz-peaked spect... | modelling of the radio spectrum evolution in the binary pulsar b1259-63 |
mass-loss in massive stars plays a critical role in their evolution, although the precise mechanism(s) responsible - radiatively driven winds, impulsive ejection and/or binary interaction - remain uncertain. in this letter, we present atacama large millimetre/submillimeter array line and continuum observations of the s... | alma observations of the supergiant b[e] star wd1-9 |
we present a study of emission lines of small hydrocarbons c2h and c-c3h2, and coms precursors h2co and ch3oh in order to better understand the possible chemical link between the molecular abundances and uv radiation field in photodissociation regions (pdrs). we study two pdrs around extended and compact h ii regions w... | dark cloud-type chemistry in photodissociation regions with moderate ultraviolet field |
based on our high-spectral-resolution observations performed with the echelle spectrograph of the 6-m telescope, we have studied the peculiarities of the spectrum and the velocity field in the atmosphere and envelope of the optical counterpart of the infrared source iras 23304+6347. we have reached the conclusion about... | peculiarities of the atmosphere and envelope of a post-agb star, the optical counterpart of iras 23304+6347 |
aims: we present new measurements of the flux densities at submillimeter wavelengths based on alma band 7 (338 ghz, λ0.89 mm) and band 9 (679 ghz, λ0.44 mm) observations to better constrain the origin of the continuum emission of the mira ab binary system and to check its orbit.methods: we have measured the mira a and ... | the radio continuum spectrum of mira a and mira b up to submillimeter wavelengths |
we present results based on ${2{^{\prime \prime}_{.}}5}$-resolution observations using the atacama large millimeter/submillmeter array (alma) of the galactic center molecular cloud g-0.02-0.07, or the 50 km s-1 molecular cloud (50 mc), in the so (nj = 22-11) line and 86 ghz continuum emission, the combination of which ... | hot molecular core candidates in the galactic center 50 km s-1 molecular cloud |
several tens of massive binary systems display indirect, or even strong evidence for non-thermal radio emission, hence their particle accelerator status. these objects are referred to as particle-accelerating colliding-wind binaries (pacwbs). wr 133 is one of the shortest period wolf-rayet + o systems in this category,... | hints about the multiplicity of wr 133 based on multiepoch radio observations |
the ionosphere of titan hosts a complex ion chemistry leading to the formation of organic dust below 1,200 km. current models cannot fully explain the observed electron temperature in this dusty environment. to achieve new insight, we have re-analyzed the data taken in the ionosphere of titan by the cassini langmuir pr... | re-analysis of the cassini rpws/lp data in titan's ionosphere: 2. statistics on 57 flybys |
the massive binary system wr 11 (γ2-velorum) has recently been proposed as the counterpart of a fermi source. if this association is correct, this system would be the second colliding wind binary detected in gev γ-rays. however, the reported flux measurements from 1.4 to 8.64 ghz fail to establish the presence of nonth... | investigation of the wr 11 field at decimeter wavelengths |
a 22 ghz water-maser survey was conducted towards 178 o-rich asymptotic giant branch (agb) stars with the aim of identifying maser emission associated with the sagittarius stellar stream. in this survey, maser emissions were detected in 21 targets, 20 of which were new detections. we studied the galactic distributions ... | water-maser survey towards off-plane o-rich agbs around the orbital plane of the sagittarius stellar stream |
all transparent high-performance solar-blind n-ito/p-nio/n-zno ultraviolet heterojunction bipolar phototransistors (hbpts) were fabricated using a low-cost radio frequency magnetron sputtering system. in the hbpt structure, ito, nio, and zno were employed as the emitter, base, and collector, respectively. the applied v... | all transparent high-performance solar-blind n-ito/p-nio/n-zno ultraviolet heterojunction bipolar phototransistor |
yellow hypergiants are rare and represent a fast evolutionary stage of massive evolved stars. that evolutionary phase is characterised by a very intense mass loss, the understanding of which is still very limited. here we report alma compact array observations of a 50''-mosaic toward the fried egg nebula, around one of... | alma compact array observations of the fried egg nebula. evidence for large-scale asymmetric mass-loss from the yellow hypergiant iras 17163-3907 |
jupiter's disc is bright in x-rays as h2 molecules in the atmosphere are very effective at scattering solar x-rays. k-shell fluorescence from carbon atoms in atmospheric methane is thought to also provide a minor contribution. xmm-newton has now observed jupiter over a span of nearly two solar cycles from 2003 to 2021,... | jupiter's equatorial x-ray emissions over two solar cycles |
we studied a number of solar active regions using two-dimensional spatially resolved microwave observations. data from the nobeyama radioheliograph and the siberian solar radio telescope together with observations by the michelson doppler imager (mdi) onboard the solar and heliospheric observatory (soho) have allowed u... | intersunspot microwave sources |
an analysis of the dependence of the local annual asymmetry r index on local time and solar activity has been performed for 1963-2013 based on the data of the medians of the maximum electron density of f2-layer nmf2 at the pair of the ionospheric stations boulder-hobart where the r index is the january-july ratio of th... | dependence of nmf2 local annual asymmetry index on local time and solar activity |
aims: we present a multiwavelength analysis of the infrared dust bubble s 24 and the extended ir sources g341.220-0.213 and g341.217-0.237 located in its environs. we aim to investigate the characteristics of the molecular gas and the interstellar dust linked to them and analyze the evolutionary state of the young stel... | molecular gas and star formation toward the ir dust bubble s 24 and its environs |
we report the result of a systematic methanol observation toward iras 19312+1950. the properties of the sio, h2o, and oh masers of this object are consistent with those of mass-losing evolved stars, but some other properties are difficult to explain in the standard scheme of stellar evolution in its late stage. interes... | methanol observation of iras 19312+1950: a possible new type of class i methanol maser |
we present submillimeter array (sma) molecular-line observations in two 2-ghz wide bands centred at 217.5 and 227.5 ghz, towards the massive star-forming region w51 north. we identified 84 molecular-line transitions from 17 species and their isotopologues. the molecular gas distribution of these lines mainly peaks in t... | complex molecules in the w51 north region |
it has been speculated that technological civilizations evolve along an energy consumption scale first formulated by kardashev, ranging from human-like civilizations that consume energy at a rate of ∼1019 erg s-1 to hypothetical highly advanced civilizations that can consume ∼1044 erg s-1. since the transmission power ... | jumping the energetics queue: modulation of pulsar signals by extraterrestrial civilizations |
a study of the plasma conditions in the atmosphere and ionosphere of the hot jupiter hd 209458b and for an hd 209458b-like planet at orbit locations of 0.2-1 au around a sun-like star is presented. it is discussed how these conditions influence the radio emission expected from the planet's magnetosphere. we find that t... | on the cyclotron maser instability in magnetospheres of hot jupiters - influence of ionosphere models |
coronal mass ejections (cmes) mostly affect the geomagnetic field. these structures are observed and studied with coronagraphic images therefore we don't see the corona in the plane of the sky and the measurements of the propagation speed for solar disk events are not accessible to coronagraphic observations. this sugg... | microwave emission of solar flares: coronal mass ejections and shock waves |
context. several massive early-type binaries exhibit non-thermal emission which has been attributed to synchrotron radiation from particles accelerated by diffusive shock acceleration (dsa) in the wind-collision region (wcr). if the magnetic field in the strong shocks is ordered, its component parallel to the shock fro... | synchrotron radiation and absence of linear polarization in the colliding wind binary wr 146 |
radio observations of young stellar objects (ysos) enable the study of ionized plasma outflows from young protostars via their free-free radiation. previous studies of the low-mass young system t tau have used radio observations to model the spectrum and estimate important physical properties of the associated ionized ... | a lofar detection of the low-mass young star t tau at 149 mhz |
we present a phenomenological study of co(1-0) and co(2-1) emission from the circumstellar envelope (cse) of the asymptotic giant branch (agb) star rs cnc. it reveals departures from central symmetry that turn out to be efficient tools for the exploration of some of the properties of the cse. we use a wind model includ... | on the central symmetry of the circumstellar envelope of rs cnc |
we present the results of a single dish interstellar maser survey toward ∼200 molecular clouds (mcs) in the extreme outer galaxy (eog) possibly lying in the outer scutum-centaurus (osc) arm. the observations resulted in the detections of two new 22.2 ghz water masers, two new 6.7 ghz class ii methanol masers, and one n... | discovery of h2o, ch3oh, and oh masers in the extreme outer galaxy |
this paper is a study of the spatial dynamics of microwave emission (data from the nobeyama radioheliograph) from two active regions noaa 12673 and noaa 11261 for several hours prior to powerful class m x-ray flares. the spatial distribution of the radio brightness and emission intensity in certain parts of the active ... | preflare dynamics of microwave and ultraviolet emission in active regions of the sun |
core-collapse sne (ccsne): systematic searches of radio emission from ccsne are still lacking, and only targeted searches of radio emission from just some of the optically discovered ccsne in the local universe have been carried out. optical searches miss a significant fraction of ccsne due to dust obscuration; ccsn ra... | core-collapse and type ia supernovae with the ska |
black holes, anywhere in the stellar-mass to supermassive range, are often associated with relativistic jets. models suggest that jet production may be a universal process common in all black hole systems regardless of their mass. although in many cases observations support such hypotheses for microquasars and seyfert ... | scale invariant jets: from blazars to microquasars |
we present x-ray and radio observations of what may be the closest type iax supernova (sn) to date, sn 2014dt (d = 12.3-19.3 mpc), and provide tight constraints on the radio and x-ray emission. we infer a specific radio luminosity $l_r\lt (1.0\!-\!2.4)\times 10^{25}\, \rm {erg\, s^{-1}\, hz^{-1}}$ at a frequency of 7.5... | constraints on the sub-pc environment of the nearby type iax sn 2014dt from deep x-ray and radio observations |
the unprecedented quality of the observations available from the atacama large millimetre/sub-millimetre array (alma) calls for analysis methods making the best of them. reconstructing in space the morphology and kinematics of radio sources is an underdetermined problem that requires imposing additional constraints for... | space reconstruction of the morphology and kinematics of axisymmetric radio sources |
context. fragmentation and feedback are two important processes during the early phases of star formation.aims: massive clumps tend to fragment into clusters of cores and condensations, some of which form high-mass stars. in this work, we study the structure of massive clumps at different scales, analyze the fragmentat... | probing the initial conditions of high-mass star formation. iii. fragmentation and triggered star formation |
we conducted radio-interferometric observations of the well-known binary cataclysmic system am herculis. this particular system is formed from a magnetic white dwarf (primary) and a red dwarf (secondary), and it is the prototype of so-called polars. our observations were conducted with the european vlbi network (evn) i... | another look at am herculis - radio-astrometric campaign with the e-evn at 6 cm |
we present observations of the cygnus ob2 region obtained with the giant metrewave radio telescope (gmrt) at frequencies of 325 and 610 mhz. in this contribution we focus on the study of proplyd-like objects (also known as free-floating evaporating gas globules or freggs) that typically show an extended cometary morpho... | radio observations of evaporating objects in the cygnus ob2 region |
relativistic jets of plasma are a key ingredient of many types of active galactic nuclei (agn). today we know that agns are powered by the accretion of interstellar material into the gravitational field of a super massive black hole, and that this process can release as much power as an entire galaxy the size of the mi... | relativistic plasmas in agn jets. from synchrotron radiation to γ-ray emission |
using the karl g. jansky very large array (vla), we have conducted a survey for 22 ghz, 61,6-52,3 h2o masers toward the serpens south region. the masers were also observed with the very long baseline array following the vla detections. we detect for the first time h2o masers in the serpens south region that are found t... | discovery of 22 ghz water masers in the serpens south region |
stellar masses are fundamental but often difficult to measure. thanks to the atacama large millimeter array (alma) and gaia, dynamical masses of pre-main sequence stars can be precisely measured using the keplerian rotation of protoplanetary disks. we used alma co(2-1) and co(3-2) observations of ct cha and ds tau to d... | dynamical masses of young stars inferred from two transitions of co with alma |
we present a systematic search for radio counterparts of novae using the australian square kilometer array pathfinder (askap). our search used the rapid askap continuum survey, which covered the entire sky south of declination $+41^{\circ}$ ( $∼$ $34000$ square degrees) at a central frequency of 887.5 mhz, the variable... | classical novae in the askap pilot surveys |
context. class ii methanol masers at 6.7 ghz originate close to high-mass young stellar objects (hmysos). their high sensitivity to local condition variations makes them a useful marker of the activity of the emerging massive stars.aims: we aim to closely examine the variability of the 6.7 ghz ch3oh masers in cep a hw2... | discovery of recurrent flares of 6.7 ghz methanol maser emission in cepheus a hw2 |
we report the first comprehensive observations of jovian synchrotron radiation (jsr) and h3+ emission from the jovian thermosphere to investigate the generation process of short-term (days to weeks) variations in the jovian radiation belt. the observations were made by the giant metrewave radio telescope and nasa infra... | relation between the short-term variation of the jovian radiation belt and thermosphere derived from radio and infrared observations |
supra-arcade downflows (sads) are infrequent, wiggly, and low-emission structures observed to descend through the solar corona, mostly in euv and soft x-ray frequencies. based on their physical characteristics, sads have been interpreted as low-density bubbles and are related to magnetic reconnection processes during l... | estimating the coronal supra-arcade downflow radio emission: from centimeter through submillimeter wavelengths |
an experimental study was made of the dependence of the electron-density perturbations in the d-regions of the midlatitude ionosphere during solar flares on the spectral composition of x-ray radiation in the wavelength range from 0.01 to 0.4 nm, i.e., outside the measurement range of the goes satellite. for this, the v... | dependence of d-region perturbations of the midlatitude ionosphere on the spectral composition of the x-ray radiation of solar flares according to experimental data |
aims: we present here a study of the cold dust in the close environs of the ring nebula gum 31. we aim at deriving the physical properties of the molecular gas and dust associated with the nebula, and investigating its correlation with the star formation in the region, which was probably triggered by the expansion of t... | 870 μm continuum observations of the bubble-shaped nebula gum 31 |
in this article we treat the non-adiabatic photon-to-axion resonant conversion of curvature radiation, synchrotron emission and inverse compton scattering dominating the spectral density function of pulsars. first, we introduce emission models and benchmark observational data. we adopt a state-of-the-art density profil... | superdense beaming of axion dark matter in the vicinity of the light cylinder of pulsars |
we present a catalog of radio sources of the m17 region based on deep x-band radio observations centered at 10 ghz obtained with the jansky very large array in the a configuration. we detect a total of 194 radio sources, 12 of them extended and 182 compact. we find that a significant fraction (at least 40% in our catal... | the population of compact radio sources in m17 |
we compiled observations of solar radio spikes (rss) reported in the literature. the compilation spans a wide range in frequency from 0.01 mhz to 8.4 ghz. we also compiled available information of energetic solar events that may be related to rss. using this compilation, though the rs events are associated with other e... | study of solar radio spikes and their relation to energetic solar events |
we present new observations of the nebula around the magellanic candidate luminous blue variable s61. these comprise high-resolution data acquired with the australia telescope compact array (atca), the atacama large millimetre/submillimetre array (alma), and the vlt imager and spectrometer for mid infrared (visir) at t... | new atca, alma and visir observations of the candidate lbv sk -67 266 (s61): the nebular mass from modelling 3d density distributions |
lrll 54361 is an infrared source located in the star-forming region ic 348 sw. remarkably, its infrared luminosity increases by a factor of 10 over roughly one week every 25.34 days. to understand the origin of these remarkable periodic variations, we obtained sensitive 3.3 cm jvla radio continuum observations of lrll ... | radio monitoring of the periodically variable ir source lrll 54361: no direct correlation between the radio and ir emissions |
context. massive binaries have stellar winds that collide. in the colliding-wind region, various physically interesting processes occur, leading to enhanced x-ray emission, non-thermal radio emission, as well as non-thermal x-rays and gamma-rays. non-thermal radio emission (due to synchrotron radiation) has so far been... | variable millimetre radiation from the colliding-wind binary cygnus ob2 #8a |
we present a multi-wavelength investigation of the h ii region g25.8700+0.1350, located in the inner part of the galaxy. in radio continuum emission, the region is seen as a bright arc-shaped structure. an analysis of the h i line suggests that g25.8700+0.1350 lies at a distance of 6.5 kpc. the ionized gas is bordered ... | a multi-wavelength analysis of the diffuse h ii region g25.8700+0.1350 |
the x-ray solar flare emissions penetrate down into the d region of the ionosphere (60-90 km of altitude) and affect the propagating very low frequency (vlf) radio signal. in this paper, we will present the effect of the solar flares on the signal mode composition of the nrk-alg path during the period from 2007 to 2013... | study of the solar flares effect on vlf radio signal propagating along nrk-alg path using lwpc code |
the reactive radio-frequency (rf) magnetron sputtering and spin coating fabrication techniques were used to fabricate y2-xo3:bix=0.5% phosphor thin films. the two techniques were analysed and compared as part of investigations being done on the application of down-conversion materials for a si solar cell. the morpholog... | comparison of y2o3:bi3+ phosphor thin films fabricated by the spin coating and radio frequency magnetron techniques |
context. asymptotic giant branch (agb) stars go through a process of strong mass loss that involves pulsations of the atmosphere, which extends to a region in which the conditions are adequate for dust grains to form. radiation pressure acts on these grains which, coupled to the gas, drive a massive outflow. the detail... | interferometric observations of sio thermal emission in the inner wind of m-type agb stars ik tauri and irc+10011 |
observations of 12co(3-2) emission of the circumbinary envelope of mira ceti, made by atacama large millimetre/sub-millimetre array, are analysed. the observed doppler velocity distribution is made of three components: a blueshifted south-eastern arc, which can be described as a ring in slow radial expansion, ∼1.7 km s... | morphology and kinematics of the gas envelope of mira ceti |
early-b stars, much less energetic than o stars, may create an h ii region that appears as radio-quiet. we report the identification of new early-b stars associated with the radio-quiet h ii region g014.645-00.606 in the m17 complex. the radio-quiet h ii region g014.645-00.606 is adjacent to three radio-quiet wise h ii... | new massive contact twin binary in a radio-quiet h ii region associated with the m17 complex |
protostellar jets are one of the primary signposts of star formation. a handful of protostellar objects exhibit radio emission from ionized jets, of which a few display negative spectral indices, indicating the presence of synchrotron emission. in this study, we characterize the radio spectra of hh80-81 jet with the he... | modeling of thermal and non-thermal radio emission from hh80-81 jet |
we investigate high time resolution data obtained by the gravitational wave high-energy electromagnetic counterpart all-sky monitor (gecam) during the flare event on 2022 april 21 at 01:52 ut. several subpeaks with durations of 4-6s have been detected in the hard x-ray precursor phase, and the key feature is that they ... | paired quasi-periodic pulsations of hard x-ray emission in a solar flare |
we present the discovery of neutral gas detected in both damped lyα absorption (dla) and h i 21 cm emission outside of the stellar body of a galaxy, the first such detection in the literature. a joint analysis between the cosmic ultraviolet baryon survey and the meerkat absorption line survey reveals an h i bridge conn... | discovery of a damped lyα absorber originating in a spectacular interacting dwarf galaxy pair at z = 0.026 |
we present a comprehensive multiwavelength investigation of a likely massive young cluster "iras 05100+3723" and its environment with the aim to understand its formation history and feedback effects. we find that iras 05100+3723 is a distant (~3.2 kpc), moderate-mass (~500 m ⊙), young (~3 myr) cluster with its most mas... | a comprehensive study of the young cluster iras 05100+3723: properties, surrounding interstellar matter, and associated star formation |
context. linear acceleration emission is one of the mechanisms that might explain intense coherent emissions of radio pulsars. this mechanism is not well understood, however, because the effects of collective plasma response and nonlinear plasma evolution on the resulting emission power must be taken into account. in a... | linear acceleration emission of pulsar relativistic streaming instability and interacting plasma bunches |
we conducted an sio maser survey towards 221 o-rich agb stars, with the aim of identifying maser emission associated with the sagittarius stellar stream. in this survey, maser emission was detected in 44 targets, of which 35 were new detections. all of these masers are within 5 kpc of the sun. we also compiled a galact... | sio maser survey towards off-plane o-rich agbs around the orbital plane of the sagittarius stellar stream |
based on the comparison of solar activity indices (annual average values of the relative number of sunspots rz 12 and solar radio emission flux at a wavelength of 10.7 cm f 12) with the ionospheric index of solar activity ig 12 for 1954-2013, we have found that the index f 12 is a more accurate (than rz 12) indicator o... | solar activity index for long-term ionospheric forecasts |
this paper presents a multiwavelength investigation of the galactic h ii region iras 17149 - 3916. using the giant meterwave radio telescope, india, first low-frequency radio continuum observations at 610 and 1280 mhz for this region are presented. the ionized gas emission displays an interesting cometary morphology, w... | galactic h ii region iras 17149 - 3916 - a multiwavelength study |
a study of quasi-periodic fluctuations of solar microwave emission at the preflare stage is presented. data from daily solar observations by the nobeyama radioheliograph at a frequency of 17 ghz are used. five flares are analyzed based on synthesized two-dimensional radio images. all of the considered events are charac... | solar-flare precursors in the microwave range |
a forward-looking facility such as the next generation very large array (ngvla) requires forward-looking science. the ngvla will enable stellar wind detections or robust constraints on upper limits sufficient to bridge the gap between current radio upper limits on cool stellar mass loss and current indirect estimates o... | quantifying the ngvla's contribution to exo-space weather: results of a community studies report next generation vla memo #31 |
remote inspection can supplement instrumentation to holistically characterize vehicle state, but for space vehicles in flight, inspection is often either risky or costly. we propose using passive inspection cubesats (pics) to reliably and affordably image the launch vehicle with fine resolution, moderate coverage, and ... | passive cubesats for remote inspection of space vehicles |
we have studied the effect of sputtering process parameters; substrate temperature, deposition pressure and sputtering power on structural and optical properties of cadmium sulfide (cds) thin films. cds thin films were deposited on glass substrate by radio frequency (rf) magnetron sputtering technique at various sputte... | effect of sputtering process parameters on structural and optical properties of cds thin films |
aims: the cyg ob2 #5 system is thought to consist of a short-period (6.6 d) eclipsing massive binary orbited by an ob-star with a period of 6.7 yr; these stars in turn are orbited by a distant early b-star with a period of thousands of years. however, while the inner binary has been studied many times, information is m... | quest for the tertiary component in cyg ob2 #5 |
we present the results of high-resolution near-ir spectroscopy toward the multiple outflows around the herbig be star lkhα 234 using the immersion grating infrared spectrograph. previous studies indicate that the region around lkhα 234 is complex, with several embedded young stellar objects and the outflows associated ... | igrins near-ir high-resolution spectroscopy of multiple jets around lkhα 234 |
radioheliograph images are essential for the study of solar short term activities and long term variations, while the continuity and granularity of radioheliograph data are not so ideal, due to the short visible time of the sun and the complex electron-magnetic environment near the ground-based radio telescope. in this... | generating a radioheliograph image from sdo/aia data with the machine learning method |
undisturbed galaxy clusters are characterized by a massive and large elliptical galaxy at their centre, i.e. the brightest cluster galaxy (bcg). how these central galaxies form is still debated. according to most models, a typical epoch for their assembly is $z$ ∼ 1-2. we have performed a detailed multiwavelength analy... | multiple agn activity during the bcg assembly of xdcpj0044.0-2033 at z ∼ 1.6 |
we report the detection of 15 ghz radio continuum emission associated with the classical cepheid variable star δ cephei (δ cep) based on observations with the karl g. jansky very large array. our results constitute the first probable detection of radio continuum emission from a classical cepheid. we observed the star a... | first detection of radio emission associated with a classical cepheid |
we present radio observations made towards the exoplanets qatar-1b and wasp-80b near 150 mhz with the giant meterwave radio telescope (gmrt). these targets are relatively nearby irradiated giant exoplanets, a hot jupiter and a hot saturn, with sizes comparable to jupiter but different masses and lower densities. both t... | search for radio emission from the exoplanets qatar-1b and wasp-80b near 150 mhz using the giant metrewave radio telescope |
we observed h2o (616→523) maser emission associated with the high-mass star-forming region iras 23139+5959 using the kava, a combination of very long baseline interferometry (vlbi) arrays between the korean vlbi network and the vlbi exploration of radio astrometry (japan). through multi-epoch kava observations, we dete... | proper motions of water masers in the star-forming region iras 23139+5939 |
atomic ionized regions with strong continuum emission are often associated with regions of high-mass star formation and low-frequency (<2 ghz) observations of these regions are needed to help build star formation models. the region toward the vela supernova remnant is particularly interesting as it is a complex stru... | a low-frequency pilot survey of southern h ii regions in the vela constellation |
we theoretically investigate the recovery of the global spectrum (monopole) from visibilities (cross-correlation only) measured by an interferometer array and the feasibility of extracting the 21 cm signal of the cosmic dawn. in our approach, the global spectrum is obtained by solving the monopole and higher-order comp... | on measuring the 21 cm global spectrum of the cosmic dawn with an interferometer array |
for the first time we present simulation results of the focusing effect of the ionospheric plasma density irregularities, namely, medium-scale traveling ionospheric disturbances (mstids), on solar radio emission by applying a ray tracing method to the earth's ionosphere with mstids. with this technique we investigate t... | simulation of focusing effect of traveling ionospheric disturbances on meter-decameter solar dynamic spectra |
many early-type stars are in systems; some of them have been indicated as putative high-energy emitters. the radiation would be produced at the region where two stellar winds collide. compelling evidence of such emission was found only for the colliding-wind binary (cwb) eta car, which was associated to a gev source. v... | is the stellar system wr 11 a gamma-ray source? |
we have analysed the emission-line properties of 6019 type ii active galactic nuclei (agns) at redshifts in the range 0.4-0.8 with [o iii] luminosities greater than 3 × 10^8 l_{\odot }, characteristic of the type ii quasars first identified in population studies by zakamska et al. the agns are drawn from the cmass samp... | emission-line properties of the most luminous agns in massive galaxies at intermediate redshifts |
this dissertation uses radio observations with the karl g. jansky very large array (vla) to investigate the mechanisms that power and shape accreting white dwarfs (wd) and their ejecta. we test the predictions of both simple spherical and steady-state radio emission models by examining nova v1723 aql, nova v5589 sgr, s... | radio observations as a tool to investigate shocks and asymmetries in accreting white dwarf binaries |
the importance of constructing wide-area sensor networks for holistic environmental state evaluation has been demonstrated. a general structure of such a network has been presented with distinction of three segments: local (based on zigbee, ethernet and modbus techniques), core (base on cellular technologies) and the s... | telecommunication platforms for transmitting sensor data over communication networks—state of the art and challenges |
vanadium oxide thin films on silicon (si) substrate are grown by pulsed radio frequency (rf) magnetron sputtering technique at rf power in the range of 100-700 w at room temperature. deposited thin films are characterized by field emission scanning electron microscopy (fesem), x-ray diffraction (xrd) and x-ray photoele... | low reflectance sputtered vanadium oxide thin films on silicon |
we present a multiwavelength study of the cometary h ii region g12.21-0.10 using the vla and ovro. both radio continuum (0.3, 0.7, 2 and 3.6 cm) and spectral lines of h41α, 13cs(2-1) & (1-0), and nh3(2,2) & (4,4) observations are included. we find two 3 mm continuum peaks toward g12.21-0.10; one of them is spat... | unveiling the hot molecular core in the ultracompact h ii region with extended emission g12.21-0.10 |
we present the results of a search for h i 21 cm line emission from the circumstellar environments of four galactic cepheids (rs pup, x cyg, ζ gem, and t mon) based on observations with the karl g. jansky very large array. the observations were aimed at detecting gas associated with previous or ongoing mass loss. near ... | a search for mass loss on the cepheid instability strip using h i 21 cm line observations |
stellar bow shocks result from relative motions between stars and their environment. the interaction of the stellar wind and radiation with gas and dust in the interstellar medium produces curved arcs of emission at optical, infrared, and radio wavelengths. we recently proposed a new two-dimensional classification sche... | bow shocks, bow waves, and dust waves. iv. shell shape statistics |
a transformative science case for the proposed next-generation very large array (ngvla) is resolving the surfaces of nearby stars, both spatially and temporally, enabled by the combination of milliarcsecond-scale resolution and unprecedented sensitivity to thermal radio emission. in a previous study, we demonstrated th... | evaluation of the ngvla revision d array configuration for stellar imaging |
in this contribution we explore the new science that a next generation very large array (ngvla) would be able to perform on the topics of the youngest hii regions and (proto)stellar jets. free-free continuum and radio recombination line (rrl) emission are often the only way of peering into the dense envelopes surroundi... | resolving the structure and kinematics of the youngest hii regions and radio jets from young stellar objects |
we observed the brackett α emission line (4.05 μm) within the nuclear starburst of ngc 253 to measure the kinematics of ionized gas, and distinguish motions driven by star formation feedback from gravitational motions induced by the central mass structure. using nirspec on keck ii, we obtained 30 spectra through a 0.5 ... | unveiling kinematic structure in the starburst heart of ngc 253 |
aims: cyg ob2 #8a is a massive o-type binary displaying strong non-thermal radio emission. owing to the compactness of this binary, emission of non-thermal x-ray photons via inverse compton scattering is expected.methods: we first revised the orbital solution for cyg ob2 #8a using new optical spectra. we then reduced a... | search for non-thermal x-ray emission in the colliding wind binary cygnus ob2 #8a |
we show that if young low-mass stars are subject to vigorous x-ray driven disc winds, then such winds may be rendered detectable in cluster environments through their interaction with ionizing radiation from massive stars. in particular we argue that in the orion nebula cluster (onc) one expects to see of order tens of... | probing x-ray photoevaporative winds through their interaction with ionizing radiation in cluster environments: the case for x-ray proplyds |
the paper aims to consider the strength gradient force as the dynamic of astrophysical jets, explaining the movement phenomena of astrophysical jets. j. c. maxwell applied the quaternion analysis to describe the electromagnetic theory. this encourages others to adopt the complex quaternion and octonion to depict the el... | dynamic of astrophysical jets in the complex octonion space |
we present optical, radio and x-ray data that confirm a new supernova remnant (snr) in the large magellanic cloud (lmc) discovered using our deep hα imagery. optically, the new snr has a somewhat filamentary morphology and a diameter of 56 × 64 arcsec (13.5 × 15.5 pc at the 49.9 kpc distance of the lmc). spectroscopic ... | optical discovery and multiwavelength investigation of supernova remnant mcsnr j0512- 6707 in the large magellanic cloud |
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