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Alice: The rosetta Ultraviolet Imaging Spectrograph
Parker, Joel Wm.; Stern, S. A.; Feldman, P. D. +8 more
We describe the design, performance and scientific objectives of the NASA-funded ALICE instrument aboard the ESA Rosetta asteroid flyby/comet rendezvous mission. ALICE is a lightweight, low-power, and low-cost imaging spectrograph optimized for cometary far-ultraviolet (FUV) spectroscopy. It will be the first UV spectrograph to study a comet at cl…
The AM CVn Systems: A Bibliographic Search for Clues to Their Cataclysmic Nature
Ulla, A.
The nature of AM CVn, GP Com, CR Boo, and V803 Cen is investigated in detail on the basis of a comprehensive review of all that to-date is known about these systems. They are classified as cataclysmic variables, within these forming the subclass of AM CVn systems; their distinguishing characteristic is an extreme H-deficiency. Besides, they are ve…
The atmospheric composition, extinction and luminosity of the LBV star R71
Stahl, O.; Lennon, D. J.; Kudritzki, R. -P. +1 more
ESO 3.6m Caspec spectra of the LMC luminous blue variable (LBV) taken at minimum have been analysed using NLTE model atmospheres and line formation calculations to derive atmospheric parameters and chemical composition. Using the silicon ionization balance and the hydrogen Balmer lines we deriveT eff =17250, log g=1.80 and a microturbu…
Doppler tomography of O-type binaries: The physical properties of seven systems
Gies, D. R.; Penny, L. R.; Bagnuolo, W. G.
We have analyzed UV photospheric lines of seven O-type binaries, by means of crosscorrelation and Doppler tomographic methods, with the goal of estimating the physical properties of the individual stars. These systems are HD 1337 (AO Cas), HD 47129 (Plaskett's star), HD 57060 (29 UW CMa), HD 37043 (Iota Ori), HD 215835 (DH Cep), HD 152218, and HD …
Massive star distribution in external galaxies and starburst regions
Conti, Peter S.
Counts of hot and luminous stars in a number of associations in the Galaxy and Magellanic Clouds enable one to directly investigate the numbers and types of massive stars. There seems to be little, if any, dependence of the slope of the Intial Mass Function, or theM upper on the initial composition of the stars. Indirect estimates of n…
Line blanketing by iron group elements in non-LTE model atmospheres of hot stars
Dreizler, Stefan; Werner, Klaus
We report on our recent progress in modeling non-LTE atmospheres of O-stars including blanketing by lines from the iron group elements. The numerical method to account for the huge number of atomic levels and line transitions is presented. Results of exploratory model calculations examining the effects on the temperature structure, the hydrogen an…
Stellar winds of massive stars in M31
Hutchings, John; Bianchi, Luciana
We have obtained the first UV high resolution spectra of hot luminous stars in M31 with the FOS onHubble Space Telescope. The spectra, combined with optical spectroscopic and photometric observations, enable us to study their stellar winds and photospheric parameters. We derive mass-loss rates and velocity laws from the wind line profiles, with th…
Aspects of data flow for an Edison-type observatory
Penny, Alan
The design of the flow of data for an Edison-type space mission, involving a large diameter telescope for use in the near-infrared and having a mission lifetime of 10-20 yrs, is discussed. Relevant lessons on data flow that can be learned from the IUE, HST, ground-based observatories, IRAS, and SOHO are briefly considered. Future design developmen…
Structure, luminosity, and dynamics of the Venus thermosphere
Bougher, S. W.; Fox, J. L.
We review here observations and models related to the chemical and thermal structures, airglow and auroral emissions and dynamics of the Venus thermosphere, and compare empirical models of the neutral densities based in large part on in situ measurements obtained by the Pioneer Venus spacecraft. Observations of the intensities of emissions are imp…
The Cataclysmic Variable Ss-Cygni
Giovannelli, F.; Martinez-Pais, I. G.
In this work we will try to give the most general panorama, comparatively with the conciseness, on SS Cygni which is the brightest dwarf nova. The dwarf novae form a sub-class of the more vaste panorama of the Cataclysmic Variables (CVs). For this reason firstly we will describe in general the CVs and the current theories which attempt to describe…