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  • 1
    Publication Date: 2011-08-17
    Description: Observations of ultraviolet variability in Wolf-Rayet stars have been made with the ANS satellite Ultraviolet Photometer Experiment. Significant variations are detected in several of the observed stars, the timescale of the variability ranging from a few minutes to several months.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society; vol. 183
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  • 2
    Publication Date: 2011-08-18
    Description: The variability of HD76536 was observed by IUE. Photometric variability is confirmed by measurements with the IUE fine error sensor. Profile changes in the ultraviolet emission lines and stellar wind absorptions were studied. Data favor a binary model with a low luminosity (perhaps compact) secondary.
    Keywords: ASTROPHYSICS
    Type: ESA 3rd European IUE Conf.; p 269-271
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  • 3
    Publication Date: 2011-08-17
    Description: Measurements of absorption at 2200 A for Sco X-1 indicate an E(B-V) of approximately 0.28. The distance to Sco X-1 is estimated to be 350 pc while the X-ray luminosity is thought to be 5 times 10 to the 36th ergs/sec. It is found that the de-reddened ultraviolet flux distribution closely resembles a blackbody at 26,000 K. Brightness variations and their relation to flickering phenomena are considered.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 227
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  • 4
    Publication Date: 2011-08-17
    Description: The first UV spectroscopic measurements of binary X-ray sources with IUE show highly variable emission from a photoionized plasma in the object HZ Her, and give evidence for localized circumsystem material in the binary source Cygnus X-1. In addition, a substantial stellar wind is found in one of the brightest identified X-ray sources HD153919. This system may be surrounded by an extensive H II region unusual in its content of high excitation ion species.
    Keywords: ASTROPHYSICS
    Type: Nature; 275; Oct. 5
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  • 5
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    In:  Other Sources
    Publication Date: 2011-08-18
    Description: Four low-resolution UV spectra of v1 Sgr (cK2) were obtained with the IUE satellite to investigate the nature of the hot component in this object, which was detected in the Astronomical Netherlands Satellite UV photometric data. The IUE results show that the spectral energy distribution of v1 Sgr in the FUV is comparable to that of a B9 star. FUV flux level, when compared with that of the mid-ultraviolet flux level, indicates that the luminosity of the hot component is roughly equivalent to that of a main-sequence star, assuming that the mid-ultraviolet flux is dominated almost entirely by a K2 I object. No discernible spectral features are present in the FUV, contrary to what may be expected in a star of B9 spectral type. Two possible interpretations are suggested: the hot component is a rapidly rotating star, or an accretion disk surrounding a central object which could be a collapsed star is being observed.
    Keywords: ASTROPHYSICS
    Type: Astronomical Society of the Pacific; vol. 94
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  • 6
    Publication Date: 2019-06-28
    Description: Ion pickup by the solar wind is a topic of current interest. In situ observations and theoretical studies establish a fairly good understanding of the physics of the ion-pickup process. In a weakly turbulent solar wind, hydromagnetic waves that are either intrinsic or excited by the newborn ions can lead to pitch-angle diffusion which can be approximately described by the quasi-linear theory with or without incorporating the resonance-broadening mechanism due to weak turbulence. According to the weak turbulence theory, the pickup ions do not form a complete spherical shell distribution in the time-asymptotic state unless the wave field is sufficiently strong. In some cases the ions only possess a partial or incomplete shell. When the solar wind is highly turbulent, direct interaction between the wave fields and the newborn ions can result in rapid pitch-angle scattering leading to swift formation of a spherical shell distribution on the time scale of an ion gyro-period.
    Keywords: ASTROPHYSICS
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  • 7
    Publication Date: 2019-06-28
    Description: The very strong, broad absorption lines of a sdOB star continuum shown in the International Ultraviolet Explorer spectrum of the Schweizer-Middleditch star projected near the center of supernova remnant SNR 1006 are investigated. It is found that strong Fe(+) resonance absorption lines are present whose centers show zero radial velocity while their profiles are broadened by approximately 5000-6000 km/s. Also identified are redshifted Si(+), Si(2+), and Si(3+) lines at velocities of approximately 5000 km/s. Results show that the absorptions must occur in the ejecta of the supernova. The strength and symmetric width of the Fe(+) line indicates that the bulk of the ejecta is iron, in agreement with the current theory for the origin of Type I supernova. It is suggested that the previous failure to detect strong Fe emission lines in the X-ray spectra of this and other young Type I SNRs may be a result of the ejecta not having had time to interact significantly with the ambient medium. In addition, the presence of redshifted adsorption lines due to supernova ejecta in its spectrum shows that this star is located behind the SNR and is not physically associated with it.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 269; June 1
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  • 8
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    In:  Other Sources
    Publication Date: 2019-06-28
    Description: Ultraviolet observations of three dwarf Cepheids (VZ Cnc, SX Phe, and AI Vel) are presented. The UV light curves are consistent with those in the visual region. When compared to standard stars, all three dwarf Cepheids exhibit flux deficiencies at the shortest observed wavelengths. The most extreme deficiencies appear for SX Phe; these may be related to the other properties previously noted for this star, including low metallicity, high space motion, and low luminosity.
    Keywords: ASTROPHYSICS
    Type: Astronomical Society of the Pacific, Publications (ISSN 0004-6280); 95; March 19
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  • 9
    Publication Date: 2019-06-28
    Description: Ultraviolet observations of nearby galaxies with the ANS are used to derive ultraviolet spectra for different galaxy types. These spectra are used with existing visible spectrophotometry to calculate K-corrections, and to predict colors and magnitudes for various galaxy types as a function of redshifts, to z = 2. No evolutionary effects are considered. It appears that the first-ranked cluster galaxies on blue emulsions should be spirals for z greater than or approximately equal to 0.5.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal Supplement Series; 43; July 198
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  • 10
    Publication Date: 2019-06-27
    Description: The paper presents photometry of the prototype W UMa binary system in three ultraviolet bands with the ANS satellite. It was found that W UMa has low-gravity darkening beta of 0.03; that temperature differences between the components not established by gravity darkening are insignificant; and that the bolometric albedo is not very large. It was also found that W UMa is limb-darkened in the ultraviolet region, and that the inner hemisphere of the less massive component is hotter than that predicted by gravity darkening and the reflection effect. It was concluded that about 20% of the surface area of the component responsible for large gravity darkening is covered by dark spots distributed uniformly in the longitudinal direction. An observational value of the convective darkening exponent of 0.054 plus or minus 0.02 is proposed.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 239
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