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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…
ISO-SWS observations of Herbig Ae/Be stars: HI recombination lines in MWC1080 and CoD -42d 11721
Benedettini, M.; Lorenzetti, D.; Nisini, B. +4 more
ISO-SWS grating spectra are obtained towards the two Herbig Ae/Be stars MWC1080 and CoD -42(deg) 11721, showing hydrogen recombination lines of the Brackett, Pfund and Humphreys series. The observed line decrements in each spectral series are consistent with emission from ionized winds, as expected from these early-type stars. We compare the obser…
The strange mid-infrared spectrum of M 31: ISOCAM observations
Sauvage, M.; Pagani, L.; Lequeux, J. +3 more
We present observations of the mid-IR spectrum of 4 small regions of M 31. The spectrum of the central 3\arcmin is characterized by a strong, broad unidentified emission band (UIB) at 11.3 mu m while the other usual UIBs at 6.2, 7.7 and 8.6 mu m are absent or very faint. We present a map of this area in the 11.3 mu m band and compare it with optic…
An Ultraviolet Spectral Atlas of 10 Lacertae Obtained with the Goddard High Resolution Spectrograph on the Hubble Space Telescope
Savage, B. D.; Ebbets, D. C.; Carpenter, K. G. +16 more
Observations of the narrow-lined O-type star 10 Lacertae taken with the Goddard High Resolution Spectrograph in 1992 November are presented. The spectra cover the wavelength range 1181-1777 Å with a resolution of 15 km s^-1 and signal-to-noise ratio greater than 100:1. Absorption lines arising in the interstellar medium, the photosphere, and the s…
Probing nuclear starburst activity in a sample of nearby spiral galaxies
Alloin, D.; Pastoriza, M. G.; Bonatto, C. +1 more
As part of a systematic study of the UV properties of galaxies in the IUE library, we present in this paper an analysis of nuclear stellar populations in spiral galaxies with radial velocity <= 5000 km/s. In this sample of 60 galaxies the IUE aperture probes a mean 1.0 kpc x 2.1 kpc area. Prior to any comparison of galaxy spectra in the range c…
Spectral decomposition by genetic forward modelling
Judge, P. G.; Brown, J. C.; Charbonneau, P. +3 more
We discuss the analysis of real and simulated line spectra using a genetic forward modelling technique. We show that this Genetic Algorithm (GA) based technique experiences none of the user bias or systematic problems that arise when faced with poorly sampled or noisy data. An important feature of this technique is the ease with which rigid a prio…
Detection of the lensing galaxy for the double QSO HE 1104-1805
Surdej, J.; Grundahl, F.; Hjorth, J. +5 more
High angular resolution ground-based direct imaging ( V, R, Ic) of the double QSO HE 1104-1805 has been obtained with the NOT and NTT telescopes. Analysis of these data led to the first detection of the lensing galaxy. Direct imaging of HE 1104-1805 has subsequently been carried out with the Planetary Camera (WFPC2) through the F555W (n…