bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sodart Telescope on Spectrum-Röntgen-Gamma and its Instrumentation
Authors: Schnopper Herbert W. 
Published: July 2016

AbstractSPECTRUM-RÖNTGEN-GAMMA (SRG) is one of a new series of large astronomical missions being planned by the Soviet Union and is scheduled for launch in mid-1993. The Space Research Institute (IKI) of the Academy of Sciences of the USSR and the Babakin Center (BC) are responsible for the scientific supervision and spacecraft construction, respectively. Mission objectives include broad and narrow band imaging spectroscopy over a wide range of energies from EUV through gamma rays with particular emphasis on extragalactic objects. The design of the Soviet Danish Röntgen Telescope (SODART) consists of two thin foil, conical shell approximations to Wolter 1 geometry. The reflectors are rolled aluminum foils which have been dipped in acrylic lacquer and coated with gold resulting in a super smooth surface. Each telescope has an aperture of 60 cm, a focal length of 8 m, a field of view of 1 deg and is designed to have a halfpower width of ≤2 arcmin. The conical geometry contributes 15 arcsec and manufacturing tolerances in the support structure and the quality of the figure of the foil the rest. The contribution from X-ray scattering is insignificant. Focal plane slides can position one of four instruments at the focus of each telescope. Images and spectra will be recorded with position sensitive proportional counters with spectral resolution as good as 13% at 6 keV. Spectral resolution of 2.5% at 6 keV is provided by an array of 19 cooled silicon detectors. A broad band polarimeter will be sensitive to residual polarization as low as 1%. An objective Bragg crystal panel, placed in front of one of the telescopes, will be capable of high resolution spectroscopic studies ((E/ΔE)) ~1000) of point- and extended sources.
An Overview of the Orbiting Solar Laboratory
Authors: Spicer D.S. 
Published: July 2016

AbstractThe Orbiting Solar Laboratory (OSL), which is a joint NASA/BMFT/ASI/ AFGL program, will be a free flying, polar orbiting complement of five scientific instruments operating as a facility and designed to observe the surface and upper atmosphere of the sun with high spatial and temporal resolution over a spectral range from the soft X-ray to the near Infrared. OSL’s primary scientific objectives are to study the coupling of velocity, magnetic, and radiation fields in the photosphere and chromosphere and to causally relate this coupling to activity in the overlying regions.To study the photosphere and chromosphere with a spatial resolution approaching 75 km OSL will utilize a 1 meter telescope, optimized for 2000–11,000 Å, to feed a narrow band tunable filter, a set of fixed broad-band filters, and a spectrograph. These three instruments share a common structure, share a unified science data and control system, and use a single-image stabilization system for their common fields of view to form a Coordinated Instrument Package (CIP). To study the transition zone a stigmatic High Resolution Telescope Spectrograph (HRTS) optimized for 1175–1700 Å, will be used capable of providing both images and spectroscopic information. A X-Ray Extreme Ultraviolet Imager and Spectroheliograph (XUVI) optimized for the 40–400 Å regime, will allow study of the corona and of multimillion degree solar transient events such as flares. Both the HRTS and the XUVI instruments will possess image stabilization systems and have a resolving power of 350 km. All OSL instruments will operate overlapping fields of view and be co-aligned. To achieve its goals the OSL will provide a total data stream of 20 M bits/s, nominally 4 M bits/s per instrument and has a planned operational lifetime of three years.
The Astrometric Imaging Telescope: Near-Term Discovery and Study of Other Planetary Systems
Authors: Levy Eugene H. , Gatewood George D. , Terrile Richard J. 
Published: July 2016

AbstractThe Astrometric Imaging Telescope (AIT) is a space-based 1.5 to 2 meter diameter telescope designed to discover and study planetary systems around other stars. The measurement objectives and instrument design aim at a definitive search for other planetary systems. The science program includes two planetary-system investigations, and the telescope carries two separate instruments: an astrometric instrument to measure the reflex motions of stars caused by the motions of unseen planets and an imaging coronagraph to directly image planets and other circumstellar matter.
Use of Libration-Point Orbits for Space Observatories
Authors: Farquhar Robert W. , Dunham David W. 
Published: July 2016

AbstractThe Sun-Earth libration points, L1 and L2, are located 1.5 million kilometers from the Earth towards and away from the Sun. Halo orbits about these points have significant advantages for space observatories in terms of viewing geometry, thermal and radiation environment, and delta-V expediture.
An X-Ray All Sky Monitor for a Japanese Experimental Module on the Space Station
Authors: Matsuoka M. , Kawai N. , Imai T. , Yamauchi M. , Yoshida A. , Kohno T. , Yoneda A. , Tsunemi H. 
Published: July 2016

AbstractWe propose an X-ray all sky monitor for Japanese Experimental Module (JEM) on the space station. Considering practical circumstances, we show as a case study that the all sky monitor with slit hole cameras is most promising for monitoring the short-term and long-term X-ray transients. We call this all sky monitor as MAXI (Monitor of All-sky X-ray Image). Position determination of gamma-ray bursts could be achieved with accuracy less than one degree observing the X-ray component of the burst. Weak X-ray sources such as active galactic nuclei could be also monitored with time resolution less than one day. The X-ray all sky monitor will work to discover X-ray novae and transient phenomena and give us the alarm for further detailed observations. The obtained data will be also used for archival study.
Transport of Solar Energetic Particles
Authors: Dröge Wolfgang 
Published: July 2016

AbstractNew developments in the understanding of the interplanetary transport of solar cosmic rays are reviewed. Based on carefully analyzed solar particle events observed on the Helios and ISEE 3 spacecraft, the relation of transport parameters to the structure of the interplanetary magnetic field is discussed. Special emphasis is given to a comparison of particle mean free paths determined from fits to intensity and anisotropy profiles with theoretical predictions derived from magnetic field spectra measured at the time of the solar particle event. Different aspects of the turbulence and wave models for the magnetic fluctuations are considered, including the effects resulting from the finite temperature of the plasma and of resonance broadening. It is found that a modified quasi-linear theory of particle scattering taking into account the effects of plasma waves propagating with respect to the average solar wind flow and the proper treatment of the dispersion relation at high wavenumber gives results which are in several cases in good agreement with particle observations in the interplanetary medium between 0.3 and 1 AU, indicating that quasi-linear theory is probably a good approximation to a full theory of solar particle transport. This has important implications for other astrophysical problems where quasi-linear theory is often used, such as the propagation and acceleration of Galactic cosmic rays and particle acceleration at shock waves.Subject headings: acceleration of particles — cosmic rays — interplanetary medium — MHD — solar wind — Sun: particle emission
Solar Hard X-Ray and Gamma-Ray Observations from GRANAT
Authors: Vilmer N. 
Published: July 2016

AbstractHard X-rays and gamma-rays are the most direct signature of the energetic electrons and ions which are accelerated during solar flares. Since the beginning of 1990 the PHEBUS instrument and the SIGMA anticoincidence shield aboard GRANAT have provided hard X-ray and gamma-ray observations of solar bursts in the energy range 0.075-124 and 0.200-15 MeV, respectively. After a brief description of the experiments, we present some results obtained on solar bursts recorded in 1990 and 1991 June. Special emphasis is given to the results related with particle acceleration during solar flares.The first part of the review is devoted to the constraints obtained on the electron acceleration timescale through the analysis of the temporal characteristics of the bursts. Combined studies of hard X-ray and gamma-ray emissions from PHEBUS and radio emissions from the Nançay Multifrequency Radioheliograph are used to infer constraints on the coronal magnetic topology involved in flares. The characteristics (location, spectrum) of the radio-emitting sources are found to vary within a flare from one hard X-ray peak to the other. Hard X-ray and gamma-ray burst onsets and rapid increases of the > 10 MeV emission are coincident with changes in the associated radio emission pattern. These results will be discussed in the context of the flare energy release.The second part of the paper concerns the heliocentric angle distribution of > 10 MeV events and presents more detailed observations of some of the largest flares in the gamma-ray line and the high-energy domains produced by ultrarelativistic electrons and > 100 MeV nucleon−1 ions. The PHEBUS observations of the gamma-ray line flare of 11 June 1991 have been used to deduce the hardness of the accelerated ion spectrum. The link between the main part of the flare and the late long-lasting >50 MeV emission detected by EGRET/COMPTON is discussed. Finally some observations of the large 1990 May 24 flare which produced a large neutron event at ground level are presented.Subject headings: acceleration of particles — Sun: flares — Sun: radio radiation — Sun: X-rays, gamma rays
Energetic-Particle Abundances in Impulsive Solar Flare Events
Authors: Reames D. V. , Meyer J. P. , von Rosenvinge T. T. 
Published: July 2016

AbstractWe report on the abundances of energetic particles from impulsive solar flares, including those from a survey of 2283He-rich events, with3He/4He > 0.1, observed by theISEE 3spacecraft from 1978 August through 1991 April. The rate of occurrence of these events corresponds to ~1000 events yr−1on the solar disk at solar maximum. Thus the resonant plasma processes that enhance3He and heavy elements are a common occurrence in impulsive solar flares. To supply the observed fluence of3He in large events, the acceleration must be highly efficient and the source region must be relatively deep in the atmosphere at a density of more than 1010atoms cm−3.3He/4He may decrease in very large impulsive events because of depletion of3He in the source region.The event-to-event variations in3He/4He, H/4He,e/p, and Fe/C are uncorrelated in our event sample. Abundances of the elements show a pattern in which, relative to coronal composition,4He, C, N, and O have normal abundance ratios, while Ne, Mg, and Si are enhanced by a factor ~2.5 and Fe by a factor ~7. This pattern suggests that elements are accelerated from a region of the corona with an electron temperature of ~3-5 MK, where elements in the first group are fully ionized (Q/A =0.5), those in the second group have two orbital electrons (Q/A~ 0.43), and Fe hasQ/A~ 0.28. Ions with the same gyrofrequency absorb waves of that frequency and are similarly accelerated and enhanced. Further stripping may occur after acceleration as the ions begin to interact with the streaming electrons that generated the plasma waves.Subject headings: Sun: abundances — Sun: flares — Sun: particle emission
Solar Simple Bursts Observed with High Spectral Resolution in the 18-23 GHz Range
Authors: Sawant H. S. , Rosa R. R. , Cecatto J. R. , Gopalswamy N. 
Published: July 2016

AbstractFor the first time, solar bursts in the frequency range of (18-23) GHz have been observed with high-time (0.6-1.2 s) and high-frequency resolution (1 GHz), by using the Itapetinga 13.7m diameter antenna. Here, we investigate the microwave type “simple low level (< 10 SFU) bursts” associated with the impulsive phase of solar flares. Observed properties of these simple bursts are: rise time tr ~3 s, decay time td ~ 5 s and spectral index ranging between −1 and −4. These bursts were found to be associated with SF or SN flares as seen in Hα. The above properties suggest that they are likely to be a microwave counterpart of elementary flare bursts. In the majority of the cases the spectral evolution is soft-hard-soft. This suggests a nonthermal gyrosynchrotron mechanism for generating these elementary flare bursts. Estimated parameters of these simple burst sources are height (h ~ 2400 km), electron density (Nє < 8.8 × 109 cm−3 ), and magnetic field (B ~ 300 G).Subject headings: radiation mechanisms: nonthermal — Sun: radio radiation
Efficiency for Electron Acceleration in Solar Energy Release Region as Estimated in the Context of Plasma Mechanism of Radio Emission
Authors: Levin B. N. , Fridman V. M. , Sheiner O. A. 
Published: July 2016

AbstractThe paper is devoted to the interpretation of spectrographic data within the frequency range 8-12 GHz. Some spectral characteristics of weak solar steplike radio bursts are reported. To explain some parameters of the emission the ability to keep superthermal electrons in a magnetic trap with dense inhomogeneous plasma is theoretically studied. On the basis of this model we estimate the energy and number of accelerated electrons, and the flux density of precipitating electrons which are the source of enhanced plasma radiation. For the obtained efficiency of electron acceleration the calculated intensity of gyrosynchrotron emission proves to be less than the observed one.Subject headings: acceleration of particles — radiation mechanisms: nonthermal — Sun: flares — Sun: radio radiation
Radiation-Driven Acceleration in Photospheres of Nonaccreting Magnetic White Dwarfs
Authors: Zheleznyakov Vladimir V. , Serber A. V. 
Published: July 2016

AbstractRadiation transfer in a pure hydrogen, fully ionized, isothermal photosphere of an isolated white dwarf with dipole magnetic field is considered, and the radiation pressure force, both in the continuum and in the cyclotron line, is determined with the line saturation effect taken into account. It is shown that the magnetic field can reduce the critical luminosity for white dwarfs. This leads to the possibility of photospheric plasma ejection driven by the radiation in the cyclotron line and the formation of radiation-driven winds from sufficiently hot isolated magnetic white dwarfs.It is shown that cyclotron radiation pressure plays a significant role in the force balance of the photospheres of the magnetic white dwarfs GD 229, GrW +70° 8247, and PG 1031+234. The strong unidentified depression in the UV spectrum of GD 229 is attributed to cyclotron scattering by the radiation-driven plasma envelope with density N ≳ 108 cm−3 .Subject headings: radiative transfer — stars: atmospheres — stars: magnetic fields — white dwarfs
Hubble Space Telescope Observations of Synchrotron Jets
Authors: Sparks W. B. , Biretta J. A. , Macchetto F. 
Published: July 2016

AbstractThe Hubble Space Telescope for the first time enables optical and UV images of jets to be obtained with spatial resolution comparable to radio interferometric techniques. Because synchrotron emission at these wavelengths is a diagnostic of particles several orders of magnitude higher in energy and correspondingly shorter in lifetime than those probed by radio, the sites of particle acceleration may be more readily identified in the optical and UV. Short-lifetime optical synchrotron emission in the SE inner radio lobe of M87 argues strongly for the presence of an invisible counterjet. A detailed comparison of HST and VLA images of the M87 jet shows there are very strong similarities in overall morphology, but that there are also significant differences. The optical and UV radiation is more localized within the knots than the radio emission and appears more confined toward the jet center. These differences may arise from localized shocks, sited at the optical knots with diffusion of relativistic particles away from those knots, or else they may be due to nonuniform magnetic fields and distributed acceleration processes. The UV fluxes of the knots are consistent with a single power law from optical to X-ray. Optical jets in other radio galaxies show diverse properties—the jet of PKS 0521–36 is smoothly resolved by HST while that of 3C 66B shows previously unsuspected filmentary structure. Likewise, the jet of 3C 273 shows newly observed optical filaments and an intensity distribution quite unlike that of the radio emission. Like M87, the optical jet of 3C 273 is narrower than the radio jet. The serendipitous discovery of a new optical synchrotron jet in 3C 264 suggests that optical jets may be relatively common.Subject heading: galaxies: jets
MONET: a MOnitoring NEtwork of Telescopes
Authors: Hessman Frederic V. 
Published: July 2016

AbstractIn an age of 8m-class telescopes, we should rethink the way we use small telescopes. While 2-4m telescopes are still needed and will continue to be operated largely in the traditional fashion, new 1m-class telescopes operated robotically in global networks will enable a wide range of new and exciting scientific and educational projects, both by themselves and in conjunction with much larger telescopes. I describe our plans for such a global network of two 1m-class robotic telescopes.
The STARBASE Network of Telescopes and the Detection of Extrasolar Planets
Authors: McGruder Charles H. , Everett Mark E. , Howell Steve B. 
Published: July 2016

AbstractA network of longitudinally spaced imaging telescopes is described. Due to the limitations of the radial velocity method extrasolar planets have only been found around bright stars (less than 10 mag). Employment of the network and the photometric method to detect extrasolar planets will lead to the discovery of extrasolar planets at much fainter magnitudes (less than 19 mag).
YSTAR: Yonsei Survey Telescopes for Astronomical Research
Authors: Byun Yong-Ik , Han Won-Yong , Kang Yong-Woo , Chun Moo-Young , Yu Sung-Yeol , Park Sun-Youp , Kim Sang-Chul , Moon Hong-Kyu , Shin Jong-Seop , Lee Kyu-Baek 
Published: July 2016

AbstractThe YSTAR program is a general sky survey looking for variability. The main equipments are three 0.5-m telescopes. These telescopes have fast F/2 optics covering nearly 3.5 square degree field onto a 2K CCD. They also have very fast slew capability, which exceeds 10 degrees per second. These two factors make them most suitable for rapid target acquisition and wide-field surveys of various kinds. Our primary objective is to identify and monitor variable stars down to 18th R-magnitude, and our observing mode allows the same data set to be also useful in identifying asteroids. Our first telescope has just begun regular automated operation, and the second telescope will be installed in South Africa within this year to provide coverage of the southern sky.
Progress Report for the KAO 1.0 meter Robotic Telescope
Authors: Mack Peter , Han Wonyong , Bradstreet Matthew , Borstad Anthony , Park Jang-Hyun , Jin Ho , Lee Woo-Baik , Lee Chung-Uk 
Published: July 2016

AbstractKorea Astronomy Observatory (KAO) is working to rebuild a 1.0-m robotic telescope in collaboration with a company (Astronomical Consultants & Equipment, Inc. or ACE). The telescope is being totally refurbished to make a fully automatic telescope which can operate in both interactive an fully autonomous robotic modes. This paper describes the design concepts and the work completed. The telescope is an f/7.5 Ritchey-Chretien system mounted on an equatorial fork with friction drives capable of high slewing (5°/s2) and high resolution tracking. The control software manages the entire telescope, instruments and observatory. In interactive local and remote modes the observer can manually enter coordinates or retrieve them from a database. In robotic mode the telescope controller downloads requests from users and creates a schedule. The telescope will be equipped with a CCD camera and will be available over the internet.
The Beijing Astronomical Observatory Supernova Survey
Authors: Qiu Yulei , Hu Jingyao , Li Weidong 
Published: July 2016

AbstractWe present here the Beijing Astronomical Observatory Supernova Survey (BAOSS). The motivation and the strategy of the survey are briefly discussed, and the hardware and the software of the system are described. BAOSS started in 1996 and has discovered 40 supernovae (SNe) in four years, thus playing an important role in the search for nearby supernovae. The results of several well-observed SNe discovered by BAOSS, SNe 1996W, 1996cb, 1997br, and 1998S, are reported.
High Speed CCD Photometry of Flare Stars
Authors: Park Sun-Youp , Byun Yong-Ik 
Published: July 2016

AbstractPreviously, flare stars have been observed by fast two channel photoelectric photometry. We have started an observing program to monitor flare stars using a normal CCD camera via a method called “trailed mode photometry”. For this program, we developed a fully automated trail photometry software.
Blazhko Cycles of ω Centauri RRab Stars
Authors: Jurcsik Johanna 
Published: July 2016

AbstractThe present observational strategy of globular cluster variables does not favour long observational runs, which are needed to study the modulation properties of Blazhko type RR Lyrae stars. The only globular cluster for which we have enough data (both photographic and CCD) to determine modulation cycles of RRab stars is ω Centauri. Any connection between the modulation periods and other stellar or cluster parameters may serve as a new clue to the explanation of the Blazhko phenomenon.
The Taiwan-America Occultation Survey for Kuiper Belt Objects
Authors: King Sun-Kun 
Published: July 2016

AbstractThe purpose of the TAOS project is to directly measure the number of Kuiper Belt Objects (KBOs) down to the typical size of cometary nuclei (a few km). In contrast to the direct detection of reflected light from a KBO by a large telescope where its brightness falls off roughly as the fourth power of its distance to the sun, an occultation survey relies on the light from the background stars thus is much less sensitive to that distance. The probability of such occultation events is so low that we will need to conduct 100 billion measurements per year in order to detect the ten to four thousand occultation events expected. Three small (20 inch), fast (f/1.9), wide-field (3 square degrees) robotic telescopes, equipped with a 2,048 × 2,048 CCD camera, are being deployed in central Taiwan. They will automatically monitor 3,000 stars every clear night for several years and operate in a coincidence mode so that the sequence and timing of a possible occultation event can be distinguished from false alarms. More telescopes on a north-south baseline so as to measure the size of an occultating KBO may be later added into the telescope array. We also anticipate a lot of byproducts on stellar astronomy based on the large amount (10,000 giga-bytes/year) of photometry data to be generated by TAOS.
The True Colors of KBOs
Authors: Hsu Hui-Chun , Ip Wing-Huen 
Published: July 2016

AbstractThe existence of a population of large planetoids outside the orbit of Neptune predicted by GP Kuiper, KE Edgeworth and JA Fernandez has been confirmed by ground-based observations.The physical properties of these Kuiper Belt Objects (KBOs) remain elusive. Photometric measurements have indicated that they have diverse color variations. A theoretical model is formulated to simulate the evolution of the surface materials of the KBOs under the influence of cosmic ray irradiation and meteoroid impacts. The long-term goal is to couple this theoretical model to observations and laboratory experiments such as LARA (Laboratory Astrochemistry and Astrophysics).