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The hot prominence periphery in EUV lines
Wiehr, E.; Stellmacher, G.; de Boer, C. R.
Two sets of He I and metallic lines were observed with the EUV spectrograph SUMER in a quiescent prominence. H, He, and Ca II lines were observed simultaneously with both German telescopes on Tenerife. The visible lines from elements with different atomic weights yield thermal and non-thermal broadening parameters of 7500 <= Tkin <…
Ultraviolet Spectroscopy of AB Doradus with the Hubble Space Telescope: Impulsive Flares and Bimodal Profiles of C IV lambda1549 in a Young Star
Collier Cameron, A.; Huovelin, J.; Hakala, P. +3 more
We observed AB Doradus, a young and active late-type star (K0-K2 IV-V, P = 0.514 days), with the Goddard High Resolution Spectrograph of the post-COSTAR Hubble Space Telescope with time and spectral resolutions of 27 s and 15 km s^-1, respectively (1994 November 14.08-14.30 UT). The wavelength band (1531-1565 Å) included the strong C iv doublet (1…
Confirmation of previous ground-based Cepheid P-L zero-points using HIPPARCOS trigonometric parallaxes
Sandage, Allan; Tammann, G. A.
Comparisons show agreement at the 0.1-mag level between the calibration of the Cepheid period-luminosity (P-L) relation by Feast & Catchpole (FC) using the early release of Hipparcos data and four previous ground-based calibrations, three of which are either largely or totally independent of the distance to the Large Magellanic Cloud (LMC). Ea…
Three-dimensional Solar Modulation of Cosmic Ray and Anomalous Components in the Inner Heliosphere
McKibben, R. B.
Our picture of modulation in the inner heliosphere has been greatly affected by observations from the Ulysses mission, which since 1992 has provided the first comprehensive exploration of modulation as a function of latitude from 80 deg S to 80 deg N heliographic latitude. Among the principal findings for the inner heliosphere are: a) the cosmic r…
Radiometric calibration tracking of the vacuum-ultraviolet spectrometer SUMER during the first year of the SOHO mission
Wilhelm, Klaus; Schühle, Udo; Brekke, Pål +3 more
Small-Scale Structure in the Lyα Forest at High Redshift
Impey, C. D.; Petry, C. E.; Foltz, C. B.
We have obtained spectra of the four components of the system B1422+231 with HST's Faint Object Spectrograph in order to study spatial inhomogeneities and velocity variations in the absorbers which are pierced by the four lines of sight. The four images are well resolved, and the spectra clearly show the system is a lensed quasar; a new redshift b…
Classical Cepheid Masses: U Aquilae
Evans, Nancy Remage; Carpenter, Kenneth; Robinson, Richard +2 more
We have obtained medium-resolution spectra (λ/Δλ ~ 20,000) of the hot binary companion to the classical Cepheid U Aql with the Goddard High Resolution Spectrograph on the Hubble Space Telescope (HST). These have been used to determine the orbital velocity amplitude. Combining this with the orbital velocity amplitude of the Cepheid from the ground-…
A Realistic Grid of Models for the Gravitationally Lensed Einstein Cross (Q2237+0305) and Its Relation to Observational Constraints
Turnshek, David A.; Chae, Kyu-Hyun; Khersonsky, Valery K.
A detailed study of a power-law lens model is presented for the gravitational lens system Q2237+0305, also known as the Einstein Cross. The adopted three-dimensional distribution for the mass of the lens is more realistic than in previous models and is described by ρ(X, Y, Z) = ρ0[1 + (X/a)2 + (Y/b)2 + (Z/c)2<…
Stereoscopic Observations of Solar Hard X-Ray Flares Made by ULYSSES and YOHKOH
Hurley, K.; Boer, M.; Niel, M. +4 more
The Solar X-Ray/Cosmic Gamma-Ray Burst Experiment aboard the interplanetary spacecraft Ulysses has provided extensive observations of solar hard X-ray flares from a variety of angles with respect to the Sun-Earth line. During the period 1991 October-1993 June, Ulysses observed 13 flares that were also observed by the X-ray instruments aboard the J…
Peaks and Troughs in Helioseismology: The Power Spectrum of Solar Oscillations
Rosenthal, C. S.
I present a matched-wave asymptotic analysis of the driving of solar oscillations by a general localized source. The analysis provides a simple mathematical description of the asymmetric peaks in the power spectrum in terms of the relative locations of eigenmodes and troughs in the spectral response. It is suggested that the difference in measured…