bluuebunny/crossref_metadata_2025_split huggingface dataset:
Observations of Southern Dwarf Novae
Authors: Vogt N. 
Published: July 2016

Preliminary results of spectroscopic and photometric data for five dwarf novae are presented :
1) V 436 Cen. The orbital period of 0.0669 days was determined from radial velocity variations. The RV half amplitude of the primary, K1. = 159 km/s, implies very small masses of M1 ≲ 0.20 M⊙ and M2 = 0.18 M⊙ for the binary components.2) Z Cha. Broad emission (Hβ, Hγ, Hδ) and superimposed narrow absorption lines of Hβ-HII, HeI 4471, Cal 4427 and Call K characterize the spectrum during quiescence. Apparently, the cool, optically thin outer disc is seen on the background of a hot continuum, originating from the white dwarf or the inner disc. The RV half amplitude K1 = 87 km/s results in masses of M1 = 1.10 M⊙ and M⊙ = 0.21 M⊙.3) EX Hya. The RV half amplitude K1 = 68 km/s reveals masses of M1 = 1.4 M⊙ and M2 = 0.19 M⊙ The equivalent widths of the emission lines of H, HeI 4471 and HeII 4686 vary with the phase of the recently detected 67 minute cycle (maximal EW coincides nearly with maximal continuum intensity).4) 0Y Car is an eclipsing binary with an orbital period of 0.0631 days. The eclipses show strong variations in shape and amplitude in the course of an outburst, similar as those of Z Cha. The observations seem to confirm that the location of the eruption is the central part of the disc which increases in size and luminosity.5) EK TrA shows periodic superhumps (P = 0.0645 days) during supermaximum, and therefore belongs to the SU UMa sub-group of dwarf novae which are also characterized by a quasi-periodic occurence of super-maxima. The SU UMa sub-group comprises 70% of the ultra-short period cataclysmic binaries, and at least 18% of all dwarf novae.
Dwarf Nova EX Hydrae
Authors: Vogt N. , Krzeminski W. , Sterken C. 
Published: July 2016

AbstractExtensive photoelectric observations of EX Hya were obtained between 1962 and 1976 at different telescopes and observatories. Evaluation of the data reveals a decrease of the orbital period at the rate Ṗ = −5.2 × 10−12. This period change is likely caused by mass transfer with angular momentum exchange between orbital motion and disc rotation on a time scale which is considerably shorter than the corresponding Kelvin – Helmholtz time scale. A rough estimate of the mass transfer rate gives Ṁ ⋍ 2 × 10−9 M⊙/yr. Gravitational radiation losses are negligible in the evolution of EX Hya. Furthermore we report the detection of a periodic modulation of the light-curve with a period of 0.046546447 days and mean amplitudes between 0.2 and 0.4 mag. (“67-minute cycle”). This oscillation remained coherent over the 14 years covered by our observations. The 67-minute variability resembles superhumps seen at supermaxima in SU UMa-type stars with the difference that it shows a 2:3 commensurability to the orbital period. We mention either (i) asynchronous rotation or pulsations of the red component, or (ii) asynchronous rotation of the magnetic primary, or (iii) resonances in the outer regions of the accretion disc as possible sources for this periodicity.
Soft X-Ray Observations of Cataclysmic Variable Stars
Authors: Córdova France 
Published: July 2016

HEAO-1 observations of a large number of cataclysmic variable stars demonstrated that most of these objects are not bright X-ray sources, even during their eruptive phases.HEAO-1 scanned about 20 dwarf novae while they were undergoing optical outbursts, yet soft X-ray emission (0.18-0.43 keV) was detected only from SS Cyg and U Gem. The 3σ upper limits to the flux from the nondetected objects, several of which were observed by HEAO-1 during more than one outburst, range from 1 to 10% of U Gem’s mean flux of ∽ 1 × 10-10 erg cm-2 s-1. SS Cyg itself was detected during outburst at an intensity 20% of this value.
Ultraviolet Studies of Novae
Authors: Friedjung M. , Rocca B. 
Published: July 2016

High dispersion spectra of WZ Sagittae and Nova Cygni 1978, taken by IUE, have been studied by us.Of the two spectra of WZ Sagittae in our possession, the long wave region one shows little besides the interstellar Mg II doublet. The more interesting short wavelength region has relatively wide (130-250 km/s) resonance absorption lines sometimes at the center of wider emission. No clear sign of ejection is seen. The study of the profiles of the CIV, NV, OI, and SiIV resonance lines and of Hell 1640 Å indicates:a) The absorption lines are probably not interstellar (widths, depths).b) A standard accretion disk model can be used. The high ionization lines are probably formed in a region ionized by the boundary layer. The line width indicates that they are formed near the edge of the disk (top of raised edge?), illuminated by radiation from a radius a factor of 10 smaller.
The Hubble Space Telescope
Authors: Boggess Albert 
Published: July 2016

AbstractThe Hubble Space Telescope was launched from the Kennedy Space Center on April 24, 1990. Its initial check-out indicates that all sub-systems of the satellite are working very well, with two key exceptions: The line-of-sight pointing is subject to occasional jitter apparently induced by thermal stresses in the solar arrays; this is expected to be overcome. The telescope mirrors are found to contain approximately 0.5 wave rms of spherical aberration which cannot be overcome by any controls on board the satellite. This defect will limit the scientific performance of the telescope in the short run. However, the aberration can be fully corrected in the optical designs of future replacement instruments, and the delivery schedules of these instruments are being accelerated.
Early Results From the Cosmic Background Explorer (COBE)
Authors: Mather J. C. , Hauser M. G. , Bennett C. L. , Boggess N. W. , Cheng E. S. , Eplee R. E. , Freudenreich H. T. , Isaacman R. B. , Kelsall T. , Lisse C. M. , Moseley S. H. , Shafer R. A. , Silverberg R. F. , Spiesman W. J. , Toller G. N. , Weiland J. L. , Gulkis S. , Janssen M. , Lubin P. M. , Meyer S. S. , Weiss R. , Murdock T. L. , Smoot G. F. , Wilkinson D. T. , Wright E. L. 
Published: July 2016

AbstractThe Cosmic Background Explorer, launched November 18, 1989, has nearly completed its first full mapping of the sky with all three of its instruments: a Far Infrared Absolute Spectrophotometer (FIRAS) covering 0.1 to 10 mm, a set of Differential Microwave Radiometers (DMR) operating at 3.3, 5.7, and 9.6 mm, and a Diffuse Infrared Background Experiment (DIRBE) spanning 1 to 300 µm in ten bands. A preliminary map of the sky derived from DIRBE data is presented. Initial cosmological implications include: a limit on the Comptonization y parameter of 10−3, on the chemical potential μ parameter of 10−2, a strong limit on the existence of a hot smooth intergalactic medium, and a confirmation that the dipole anisotropy has the spectrum expected from a Doppler shift of a blackbody. There are no significant anisotropies in the microwave sky detected, other than from our own galaxy and a cosθ dipole anisotropy whose amplitude and direction agree with previous data. At shorter wavelengths, the sky spectrum and anisotropies are dominated by emission from ‘local’ sources of emission within our Galaxy and Solar System. Preliminary comparison of IRAS and DIRBE sky brightnesses toward the ecliptic poles shows the IRAS values to be significantly higher than found by DIRBE at 100 μm. We suggest the presence of gain and zero-point errors in the IRAS total brightness data. The spacecraft, instrument designs, and data reduction methods are described.
The Advanced X-Ray Astrophysics Facility
Authors: Weisskopf M.C. 
Published: July 2016

AbstractThe Advanced X-Ray Astrophysics Facility (AXAF) is a remarkable and unique scientific endeavor. It will be a space-based earth orbiting X-ray observatory, designed to address fundamental questions in astronomy and astrophysics. It is remarkable in that it represents enormous advances in observational capability. It is unique in that it will be the best means of obtaining high resolution, spectrally resolved X-ray images of astronomical objects for the rest of this century and beyond.
The X-Ray Timing Explorer
Authors: Bradt H. V. , Levine A. M. , Morgan E. H. , Remillard R. A. , Swank J. H. , Dingus B. L. , Holt S. S. , Jahoda K. M. , Rothschild R. E. , Gruber D. E. , Hink P. L. , Pelling R. M. , Jernigan J. G. 
Published: July 2016

AbstractThe capabilities of the X-ray Timing Explorer (XTE) are described with particular attention paid to current scientific problems it will address from galactic neutron star systems to active galactic nuclei. It features a low-background continuous 2-200 keV response with large apertures (a 0.63-m2 proportional counter array and a 0.16-m2 dual rocking NaI/CsI scintillation array). Rapid response (in hours) to temporal phenomena, e.g. transients, is obtained by virtue of a scanning all-sky monitor and rapid maneuverability. XTE will carry out detailed energy-resolved studies of phenomena close to neutron stars (e.g. QPO’s) because of its sub-millisecond timing (to 10 μs), its high telemetry rates (to 256 kb/s), and the high throughput of its data system (to ≳ 2 × 105 c s−1).
Far and Extreme Ultraviolet Astronomy with Orfeus
Authors: Krämer G. , Barnstedt J. , Eberhard N. , Grewing M. , Gringel W. , Haas C. , Kaelble A. , Kappelmann N. , Petrik J. , Appenzeller I. , Krautter J. , Mandel H. , Östreicher R. , Bowyer S. , Hurwitz M. 
Published: July 2016

AbstractORFEUS (Orbiting and Retrievable Far and Extreme Ultraviolet Spectrometer) is a 1 m normal incidence telescope for spectroscopic investigations of cosmic sources in the far and extreme ultraviolet spectral range. The instrument will be integrated into the freeflyer platform ASTRO-SPAS. ORFEUS-SPAS is scheduled with STS ENDEAVOUR in September 1992. We describe the telescope with its two spectrometers and their capabilities i.e. spectral range, resolution and overall sensitivity. The main classes of objects to be observed with the instrument are discussed and two examples of simulated spectra for the white dwarf HZ43 and an O9-star in the LMC are shown.
IRTS: Infrared Telescope in Space
Authors: Matsumoto Toshio 
Published: July 2016

AbstractIRTS is a small cryogenically cooled telescope onboard the small space platform SFU (Space Flyer Unit). SFU will be launched with the new Japanese HII rocket on January 1994 and retrieved by the space shuttle.The IRTS telescope has an aperture of only 15 cm diameter, but is optimized to observe diffuse extended infrared sources. Four focal plane instruments are being developed under collaboration between Japan and the U.S.A. IRTS covers a wide wavelength range from near-infrared to submillimeter region, and has a capability for the spectroscopic measurement. Due to newly developed detectors, the sky will be surveyed with very high sensitivities. IRTS will provide valuable data on cosmology, galactic structure, cosmic dust, etc.
The Submillimeter Wave Astronomy Satellite
Authors: Melnick G.J. 
Published: July 2016

AbstractThe Submillimeter Wave Astronomy Satellite (SWAS) is a NASA Small-Explorer Class experiment whose objective is to study both the chemical composition and the thermal balance in dense (NH2 > 103 cm−3) molecular clouds and, by observing many clouds throughout our galaxy, relate these conditions to the processes of star formation. To conduct this study SWAS will be capable of carrying out both pointed and scanning observations simultaneously in the lines of four important species: (1) the H2O (110–101) 556.963 GHz ground-state ortho transition, (2) the O2 (3,3–1,2) 487.249 GHz transition, (3) the CI (3P1 – 3P0) 492.162 GHz ground-state fine structure transition, and (4) the 13CO (J = 5–4) 550.926 GHz rotational transition. These atoms and molecules are predicted to be among the most abundant within molecular clouds and, because they possess low-lying transitions with energy differences (ΔE/k) between 15 and 30K (temperatures typical of many molecular clouds), these species are believed to be dominant coolants of the gas as it collapses to form stars and planets. A large-scale survey in these lines is virtually impossible from any platform within the atmosphere due to telluric absorption.
VSOP, A Space VLBI Programme
Authors: Hirabayashi H. 
Published: July 2016

AbstractVSOP, VLBI Space Observatory Programme, is an approved space VLBI programme of ISAS for the study of very compact radio sources with the synthesized aperture of 30,000 km diameter, by connecting an orbiting radio observatory with ground radiotelescopes. The VSOP satellite carrying 10 m antenna with 1.6, 5, and 22 GHz band receivers will be launched in early 1995 by M-V rocket of ISAS into an eccentric orbit with 20,000 km in apogee height. The tracking network will be formed for the satellite orbit determination, phase transfer and IF down-link. VSOP aims imaging capability with best resolution of 0.0001 arc second in 22 GHz band. Imaging of active galactic nuclei, star forming regions and stellar objects, and radioastrometry are main scientific targets.
VLBI with TDRSS
Authors: Linfield R. P. 
Published: July 2016

AbstractVLBI observations using a satellite in earth orbit and ground antennas in Japan and Australia were conducted in 1986, 1987, and 1988. Sources were detected on space-ground baselines at both observing frequencies: 2.3 and 15 GHz. The coherence on space-ground baselines for 340 s was 90% at 2.3 GHz and 76% at 15 GHz. Brightness temperatures in the range 1–4×1012 K were measured for 10 sources at 2.3 GHz and 6 sources at 15 GHz.
The Planetenteleskop Mission
Authors: Neukum G. 
Published: July 2016

AbstractThe scientific focus of the Planetenteleskop project will be on time-variable solar system phenomena (planet-magnetosphere-satellite interactions, active processes of cometary nuclei, atmospheric circulation and dynamics), on time-invariant solar system phenomena (geochemical provinces on planetary and satellite surfaces, global characteristics of primitive bodies), on planetary environments of other stars, and on general astronomical and astrophysical applications. The proposed Planetenteleskop in elliptical 24 h earth orbit will combine near-simultaneous, high-resolution spectroscopic observations, diffraction-limited imaging quality, long integration times (< 10 h) and excellent target tracking accuracy (nominally 0.05 arc sec/10 h, up to 0.02 arc sec). The excellent tracking accuracy and stability on extended objects and features is provided by a novel real-time on-board image correlation scheme. The Planetenteleskop has been studied in prephase A and phase A by industry and the involved science community in Germany in cooperation with American colleagues.
Future Solar System Missions
Authors: Briggs Geoffrey A. 
Published: July 2016

After a decade long hiatus in launches beyond Earth orbit, NASA’s planetary exploration program is again moving forward, beginning with the Magellan launch to Venus in May 1989 and the Galileo launch to Jupiter in October 1989. These spacecraft will reach their targets in August 1990 and December 1995, respectively. Both are missions of longstanding priority, Magellan to provide the first global high resolution mapping of the cloud-shrouded Venus surface, Galileo to make comprehensive measurements of the Jovian system in follow-up to the 1979/1980 Voyager flybys.Beyond these two missions there are other already approved missions: the Mars Observer for launch in 1992, the Comet Rendezvous and Asteroid Flyby CRAF mission (Fig. 1) for launch in 1995, and the Cassini mission (Figs. 2 and 3) to Saturn and its moon Titan for launch in 1996. The very diversity of these five missions and their targets (Venus, the Jovian system, Mars, comet Kopff, asteroids Gaspra and Ida by Galileo, Hamburga by CRAF, and Maja by Cassini, and the Saturnian system, is indicative of the strategy being pursued in the program: one of deliberate breadth that seeks to explore all three main classes of solar system bodies (the terrestrial planets, the outer giants and their moons, and the primitive small bodies).
The Ulysses Mission in the High Latitude Heliosphere
Authors: Page D.E. , Marsden R.G. , Smith E.J. , Wenzel K.-P. 
Published: July 2016

AbstractUlysses, a joint ESA/NASA mission launched in October 1990, will be the first to explore the high latitude heliosphere. Launch will be from the Shuttle and a Jupiter gravity assist will be used to send the spacecraft first over the southern solar pole approximately three and one half years after launch and then over the northern solar pole one year later. Instruments will be carried to study the solar wind, the heliospheric magnetic field, energetic solar particles, galactic cosmic rays, solar X- rays, cosmic gamma rays cosmic dust and interstellar neutral helium. The radio signals used to track and transmit spacecraft data will be used also to sound the corona and to search for gravitational waves.
Launch Vehicles of the Future: Earth to Near-Earth Space
Authors: Keyworth G. A. 
Published: July 2016

None of us thought, when this colloquium was scheduled, that the timing would enable it to become a celebration as well. The launch, after years of postponements, of the Hubble Space Telescope, has cast a galactic glow over the proceedings here this week. But at the same time, the frustrating delays caused by the collapse in 1986 and very slow regeneration of the U.S. space launch capabilities since then make this discussion of near-earth access very pointed.As we know, the sheer momentum of the U.S. Space Shuttle Program has dominated our perceptions of space launch for a decade and a half. It reached its peak in the early 1980s when our national policy placed nearly total reliance on the Shuttle as our means of access to space. It was a policy doomed to fail, for obvious and not-so-obvious reasons.
SIXA: The Solid State Spectrometer Array Onboard Spectrum-X-Gamma
Authors: Vilhu O. , Sipilä H. , Kämäräinen V.J. , Taylor I. , Laegsgaard E. , Leppelmeier G. , Schnopper H.W. 
Published: July 2016

AbstractThe SPECTRUM - X-GAMMA mission is being developed by the Space Research Institute (IKI), USSR, together with many other countries and is scheduled for launch in 1993 ( Sunyaev,1990; Schnopper,1990). Mission objectives include broad and narrow band imaging spectroscopy over a wide range of energies from the EUV through gamma rays, with an emphasis on studying galactic and extragalactic X-ray sources. The Danish Space Research Institute (DSRI) and IKI will provide two thin-foil X-ray telescopes (SODART), each with an aperture of 60 cm and focal length of 8 m. They are designed to have a half-power width of less than 2 arc minutes and will have collecting areas of 1700, 1200 and 100 cm2 at 1, 8 and 20 keV, respectively. Images and polarization will be recorded by position-sensitive proportional counters. Moderate resolution spectroscopy will be done by the segmented solid state detector SIXA (Silicon X-ray Array), designed and to be constructed by a consortium in Finland, Denmark and USSR. Finland will have the main responsibility in financing and delivering the detector. The Institute of Electromechanics in Moscow will provide its passive cooling system (110 K). The detector will consist of 19 segments (Si(Li)), each with a diameter of about 8 mm. The spectral resolution of 160 eV (at 6 keV), combined with the large collecting area, provide good opportunities for time-resolved iron line spectroscopy ( 6-8 keV). The potential observing program includes stellar coronae, cataclysmic variables and X-ray binaries, accretion discs and coronae of neutron stars and black hole candidates, supernova-remnants, active galactic nuclei, clusters of galaxies and the diffuse cosmic X-ray background. We demonstrate the instrument’s power through some astrophysical simulations.
The Astro Mission
Authors: Gull T.R. 
Published: July 2016

AbstractThe Astro Mission, an attached payload dedicated to astronomy, is now scheduled to fly May 9, 1990 in the shuttle Columbia. Four instruments make up the complement. Broad Band X-Ray Telescope (BBXRT, Peter Serlemitsos, Principal Investigator GSFC) utilizes the Two Axis Pointing System (TAPS). The three ultraviolet instruments are Hopkins Ultraviolet Telescope (HUT, Arthur Davidson, JHU), Ultraviolet Imaging Telescope (UIT, Ted Steccher, GSFC) and Wisconsin Ultraviolet Photopolarimeter Experiment (WUPPE, Art Code, UWI). The instruments are co-aligned in the Spacelabs Instrument Pointing System (IPS). Five of the seven astronauts are professional astronomers. Mission Specialists Mike Lounge, Jeff Hoffman, and Robert Parker, and Payload Specialists Samuel Durrance and Ron Parise. During the planned ten-day mission, over 290 shuttle manoeuvres will enable approximately 1000 individual instrument observations of 230 separate astronomical objects. The Astro mission is designed for multiple flights.
An Observatory for Mapping the Far UV Diffuse Galactic Emission Line Background
Authors: Roesler F.L. , Harlander J. , Reynolds R.J. 
Published: July 2016

AbstractA new instrumental concept for interference spectroscopy called Spatial Heterodyne Spectroscopy (SHS) is described. This instrument as currently demonstrated could provide important information on the structure, excitation, and dynamics of the ≃ 105 K component of the interstellar medium by providing velocity-resolved (20 km s−1) maps of the faint FUV emission line background over a hemisphere of the sky within a 5-6 year observation period. We are currently studying concepts expected to reduce this time by at least an order of magnitude.In the SHS technique, an all-reflection dispersive interferometer produces a Fourier transform of the spectrum as two-dimensional spatial frequencies on an imaging detector. The system does not require scanning, and measures its own internal alignment state. Although the system suffers the conventional Fourier transform multiplex disadvantage associated with the photon noise in the background FUV continuum, we estimate that for a broad-band survey Spatial Heterodyne Spectroscopy as currently demonstrated can provide 4-5 fold gains over practical grating spectrometers of similar dimensions and spatial and spectral resolution. Field widened methods currently being studied promise additional gains of two orders of magnitude.
Edison: A Second Generation Infrared Space Observatory
Authors: Thronson H.A. , Hawarden T.G. , Mountain C.M. , Davies J.K. , Lee T.J. , Longair M. 
Published: July 2016

AbstractEDISON is a large-aperture telescope under study for the second generation of infrared space observatories, whether in orbit or on the moon. The optics equilibrate via radiative cooling to temperatures between 40 and 80 K, depending upon, for example, telescope structure and location. At these temperatures, telescope emission is below that of the astronomical background at all wavelengths shortward of 20-40 μm. The detector components can be cooled via mechanical refrigerators now in an advanced stage of development. A mixture of radiative and mechanical cooling means that there is no natural limit to EDISON’s lifetime. In addition, the upper stage rocket fairing can be almost filled with light-collecting optics and alternative low-emissivity optical designs, such as off-axis systems, can be easily engineered. We are presently evaluating a design for a 2.5 m observatory to be launched in collaboration with European astronomers as part of the NASA Explorer program. In this presentation, we describe possible spectroscopic and spectrophotometric studies of very faint infrared sources that will require large-aperture space telescopes working at the celestial background limit.