Search Publications
Missions
Journals
Publication Years
Precise measurement of the right ascension of the Geminga pulsar using COS-B data.
Li, T. P.; Cheng, L. X.; Ma, Y. Q. +2 more
We have obtained a more precise value of the right ascension and a new spin evolution law of the Geminga pulsar using COS-B data on the assumption 0r high stability of the absolute phase. The new value is a(1950)=6h30m59s .057, with error about 0.5 arcsec, compared with the 3.2 arcsecs from the Einstein HRI result.…
Comparisons of IUE & HST ultraviolet spectra of extragalactic H II regions.
Terlevich, E.; Terlevich, R.; Garnett, D. R. +5 more
The authors compare recently obtained HST FOS and IUE SWP ultraviolet spectra of two extragalactic H II regions: SBS 0335-052 and 30 Doradus in the LMC. They also present IUE SWP NEWSIPS processed spectra of I Zw 18, which show significant improvements in the data quality, suggesting that reprocessed IUE archival spectra will offer enhanced scienc…
Model Atmospheres: Tool for Identifying Interstellar Features
Frisch, P. C.; Slojkowski, S. E.; Rodriguez-Bell, T. +1 more
Model atmosphere parameters are derived for 14 early A stars with rotation velocities, from optical spectra, in excess of 80 km/s. The models are compared with IUE observations of the stars in regions where interstellar lines are expected. In general, with the assumption of solar abundances, excellent fits are obtained in regions longward of 2580 …
The Ultraviolet Spectrum of the Binary System Ty-Pyxidis
Danezis, E.; Theodossiou, E.; Antonopoulou, E.
A detailed list and analysis of line identifications of five UV spectra of the RS CVn-type binary system TY Pyxidis are presented. These spectra are recorded at different phases with the International Ultraviolet Explorer (IUE). Two of them are in the wavelength rangeλλ1235–1950 Å while the other three in the rangeλλ2700–3110 Å. The far-UV spectru…
Anisotropy measurements and spectra from a solar proton event in March 1991
Balogh, A.; Forsyth, R. J.; Cowley, S. W. H. +2 more
We use observations from the Anisotropy Telescopes on the Ulysses spacecraft to determine the omnidirectional flux profile of protons in the energy range 0.7 - 1.3 MeV, during the solar proton event that began on 23 Mar 1991. We also show the spectral index throughout the event at 0.7 - 2.2 MeV and at 2.2 - 6.5 MeV, with three example spectra, one…
Gas dynamics of solar wind interaction with interstellar gas: theory and experiment.
Baranov, V. B.
A survey of the current situation in gas dynamic models of solar wind interaction with the local interstellar medium (LISM) is presented. The role of these models in interpreting a number of observed physical phenomena is investigated. Attention is concentrated on the self-consistent gas dynamic model of solar wind interaction with the supersonic …
Interstellar extinction: a parametrical study by using laboratory data.
Mennella, V.; Colangeli, L.; Rotundi, A. +2 more
The authors present a comparative study between laboratory data, astronomical observations and theoretical models in order to provide a contribution to the characterization of cosmic-dust properties. In particular, they propose a parametrization of the amorphous-carbon extinction curve. The laboratory extinction measurements, performed in the extr…
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…
Ulysses-its status and prospects
Wenzel, K. -P.
The Ulysses spacecraft is in a high-inclination solar orbit to reach the south polar regions of the Sun in mid-1994 and the north polar regions about one year later. The spacecraft and its nine scientific instruments are in good health. An extended mission, i.e. a second orbit with polar passes about half an 11-year solar cycle later, is scientifi…
Theoretical Modes Fitting on Miras Light Curves
Barthes, D.; Mennessier, M. O.; Mattei, J. A. +1 more
Visual observations of long period variable stars over 20 years were provided by the American Association of Variable Stars Observers (AAVSO), and were analyzed as part of the preparation of the HIPPARCOS mission. A set of frequencies is extracted from the light curve by using Fourier transform, preliminary Van Cittert deconvolution and comparison…