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The Supergiant Binary BM CAS
Evans, N. R.; Fernie, J. D.
Attracted by an earlier claim (Thiessen 1956) that BM Cas is an eclipsing binary with one component a classical Cepheid, we have obtained new photometry and IUE ultraviolet spectra of the system. While we verify that there is variability in addition to the eclipses, we conclude that there is no classical Cepheid present. The variability is irregul…
A Transition Disk Model Fit for the Broadband X-Ray Spectrum of Cygnus X-1
Rao, A. R.; Misra, R.; Melia, F. +1 more
The broadband (2-500 keV) data for Cygnus X-1 from observations by EXOSAT, OSSE, and the XMPC balloon, have been fitted to the transition disk model. In this model the emission is from the inner region of an accretion disk where the temperature is a rapidly varying function of radius and the radiative mechanism is saturated Comptonization. We fit …
Far-Ultraviolet Imaging of the Large Magellanic Cloud Populous Cluster NGC 1978 with WFPC2
Casertano, Stefano; Cole, Andrew A.; Ballester, Gilda E. +13 more
We have imaged the ∼2.2 billion-year-old Large Magellanic Cloud populous cluster NGC 1978 in the far-ultraviolet and visible with the second Wide Field/Planetary Camera (WFPC2) on the Hubble Space Telescope. The far-ultraviolet images show a sparse stellar field with little apparent density enhancement in the cluster core. The visible images are d…
Far-Ultraviolet Observations with the Voyager Ultraviolet Spectrometer: New Evidence for Interacting Winds in Symbiotic Systems
Leahy, D. A.; Li, P. S.
The interacting winds model has been used to explain many observational phenomena of symbiotic systems and planetary nebulae successfully. New observational results on seven symbiotic systems, obtained by the ultraviolet spectrometer (UVS) on board of spacecrafts Voyager 1 and Voyager 2, provide strong new evidence supporting the interacting winds…
The Luminosity Function for L > L* Galaxies at z > 3
Bershady, Matthew A.; Majewski, Steven R.; Koo, David C. +2 more
Through the use of multiband (U,BJ,RF,IN) photometry we have isolated high-redshift (3.0<z<3.5) galaxy candidates in surveys of 1.27 deg2 to RF=21.25 and 0.02 deg2 to RF=23.5. Our pool of candidates constrains the nature of the 3.0<z<3.5 luminosity function ov…
Impact of Magnetic Environment on the Generation of High-Energy Neutrons at the Sun
Torsti, J.; Usoskin, I. G.; Kocharov, L. G. +3 more
This paper demonstrates the important interplanetary manifestation of strongly tilted magnetic fields at the flare site. We start with analysis of Big Bear Solar Observatory (BBSO) observations of magnetic structures at sites of two flares responsible for >100 MeV neutron events. Based on these observations, a model of neutron production is con…
The Galactic Cosmic Ray 36Cl Clock: ULYSSES HET Results
Simpson, J. A.; Du Vernois, M. A.; Connell, J.
Chemical vapor deposited silicon carbide mirrors for extreme ultraviolet applications
Saha, Timo T.; Leviton, Douglas B.; Fleetwood, Charles M. +5 more
Advances in optical coating and materials technology have made possible the development of instruments with substantially improved efficiency in the extreme ultraviolet (EUV). For example, the development of the chemical vapor deposition (CVD) SiC mirrors provides an opportunity to extend the range of normal-incidence instruments dow to 60 nm. CVD…
The Program to Link the HIPPARCOS Reference Frame to an Extragalactic Reference System Using the Fine Guidance Sensors of the Hubble Space Telescope
Benedict, G. F.; Franz, O. G.; Hemenway, P. D. +19 more
The Hipparcos Satellite Mission has produced positions, proper motions, and parallaxes of unprecedented accuracy for 118,000 stars. For the positions and proper motions to represent true directions and physical motions in space, they must refer to an accurate realization of a nonrotating (inertial) reference frame. One of the major problems confro…
The Jet Driven Motions in the Narrow Line Region of NGC 1068
Robinson, Andrew; Axon, David J.; Marconi, A. +2 more
We have obtained HST FOC f/48 long-slit spectroscopy of the central 2 arcseconds of the Narrow Line Region of NGC 1068 between 3500-5400\OA with a spectral resolution of 1.78\OA/pixel. At a spatial scale of 0″.0287 per pixel these data provide an order of magnitude improvement in resolution over previous ground based spectra and allow us to trace …