Search Publications
Energetic and relativistic nuclei and electron experiment of the SOHO mission
Valtonen, E.; Peltonen, J.; Peltonen, P. +17 more
The design of the ERNE experiment of the ESA and NASA collaborative SOHO mission is described. ERNE will investigate the sun by measuring energetic particles. Starting from the design objectives, as determined by the scientific goals of the experiment, and from the adopted basic solutions, the design and structure of the instrument are presented i…
RY Persei: an Early-Type Interacting Close Binary
Olson, Edward C.; Plavec, Mirek J.
We have analyzed photometric and spectroscopic data for the totally-eclipsing binary RY Persei. It is a semidetached binary of the Algol type. However, both the gainer (B4: V) and the loser (F7: II-III) are significantly more massive (6.25 and 1.6 M_sun), hotter, and more luminous (Mbol about -3.3 and -0.2 mag, respectively) than a typi…
Using photochemistry to explain the formation and observation of C 2 in comets
Weaver, Harold A.; A'Hearn, Michael F.; Sorkhabi, Osman +4 more
Laboratory data taken from the laser-induced fluorescence (LIF) spectrum of C 2(X 1Σg+) radicals produced during the 193 nm laser photolysis of C 2H 2 has been used to explain the band profiles of the Hubble Space Telescope (HST) on nucleus spectra of the C 2 Mulliken sys…
High-Resolution Hubble Space Telescope Observations of Zn II and CR II Absorption toward the Magellanic Clouds
Roth, Katherine C.; Blades, J. Chris
We present high-resolution (3.5 km s-1) spectra of Zn II and Cr II absorption obtained with the Hubble Space Telescope toward four Magellanic Cloud stars. We have detected absorption from the full extent of the Milky Way disk + halo with an average depletion measure of [Cr/Zn] = -1.07 +/- 0.05. In addition, we identify absorption from t…
Models of optical/UV continuum in AGN: constraints from the NGC 5548 monitoring campaign
Czerny, B.; Loska, Z.
We analyse the data from the International Ultraviolet Explorer (IUE) observational campaign on the Seyfert galaxy NGC 5548 in the context of 10 phenomenological models. On the basis of the optical/UV data, as well as of constraints from the X-ray observations, we can favour one model of the nucleus: an accretion disc with an inner radius cut-off …
Hubble Space Telescope observations of M31 associations
Magnier, Eugene A.; Lewin, Walter H. G.; van Paradijs, Jan +2 more
We have used HST WFPC-2 observations of five fields along the eastern spiral arm regions of M31 to study the stellar populations. We use fits to stellar models to determine extinction individually for the stars in OB associations in these fields. The range of extinction within each cluster is the major constraint on our ability to determine accura…
Mass determination of astrometric binaries with Hipparcos. I. Theory and simulation
Mignard, F.; Martin, C.; Froeschle, M.
The analysis of the observations of double stars made by the ESA satellite Hipparcos has involved a very specific processing to derive the relevant astrometric parameters. This required to distinguish between several categories of double stars according to the separation and orbital motion. We show that for close pairs with orbital period less tha…
Far-Ultraviolet Absorption Lines in the Remnant of SN 1006
Sarazin, Craig L.; Crenshaw, D. Michael; Fesen, Robert A. +3 more
We have obtained a far-ultraviolet spectrum (1150-1600 Å) of a hot subdwarf star behind the remnant of supernova 1006 with the Faint Object Spectrograph (FOS) on the Hubble Space Telescope. The high-quality spectrum is used to test previous identifications of the strong absorption features discovered with the International Ultraviolet Explorer. Th…
The Mass of the Classical Cepheid S Muscae
Carpenter, Kenneth; Robinson, Richard; Beck-Winchatz, Bernhard +2 more
A good determination of the mass-luminosity relation for evolved stars on blue loops can determine the degree of excess mixing in the interiors of their main-sequence companions. In this study we determine the dynamical mass of the Cepheid binary S Muscae. This can be combined with its known luminosity and be fitted on evolutionary tracks to deter…
Extreme Ultraviolet Photometry and Spectroscopy of BL Hydri
Vennes, Stéphane; Szkody, Paula; Howell, Steve B. +2 more
We have analyzed Extreme Ultraviolet Explorer (EUVE) observations of BL Hyi obtained during a high-accretion state in 1995 October. The light curve obtained with the Deep Survey instrument reveals a broad hump covering the phases in which both poles have been known to be active in X-ray emission. In contrast to the X-ray, both poles contribute a c…