Search Publications
Analysis of the Si IV Ultraviolet Spectra of U Sagittae
Richards, Mercedes T.; Kempner, Joshua C.
Archival IUE spectra of U Sge have been used to study hot (~105 K) circumstellar gas in this system. The observed spectra contain several UV resonance lines, of which the Si IV lines (λλ1394 and 1405) are the strongest. These lines are observed in absorption, so we must remove the photospheric absorption line contribution to the spectra…
Distance and absorption of the tails in the CG 30/CG 31/CG 38 complex. an application of a (V-I)_0 - M_V main sequence relation derived from the HIPPARCOS and TYCHO catalogues
Knude, J.; Nielsen, A. S.; Jønch-Sørensen, H.
From a mosaic of rather deep V and I images of the CG 30/CG 31 region we report distances and absorptions of these and other interesting interstellar features, the distances and absorptions estimates are based on shifting a new (V-I)_0 - M_V relation obtained from nearby, presumably unreddened Hipparcos stars with luminosity class V classification…
Orbits of Five Visual Double Stars
Docobo, J. A.; Ling, J. F.
This paper revises and discusses the orbits and other parameters of the double stars WDS 01497-1414, WDS 05413+1632, WDS 11136+5525, WDS 20311+3333, and WDS 20494+1124.
X-Ray Properties of the Weak Seyfert 1 Nucleus in NGC 4639
Ho, Luis C.; Kunieda, Hideyo; Serlemitsos, Peter J. +4 more
Low-luminosity active galactic nuclei (AGNs), of which NGC 4639 is a good example, constitute an important but poorly understood constituent of the nearby galaxy population. We obtained observations of NGC 4639 with ASCA in order to investigate its mildly active Seyfert 1 nucleus at hard X-ray energies. Koratkar et al. have previously shown that t…
HST Detection of H 2 Raman Scattering in the Jovian Atmosphere
Yelle, Roger V.; Bétremieux, Yan
Raman scattered features by molecular hydrogen have been detected in Hubble Space Telescope (HST) Faint Object Spectrograph (FOS) observations of Jupiter. The measurements were obtained with the G190H grating and red detector combination spanning 158.0-232.0 nm at about 0.3 nm resolution. The data were corrected for scattered light, and careful mo…
Infrared Spectral Imaging of Martian Clouds and Ices
Bell, James F.; Howell, Robert R.; Klassen, David R. +4 more
Multispectral images of Mars, taken at the NASA Infrared Telescope Facility (IRTF) near and at the 1995 opposition, are used to identify and track its atmospheric clouds and ground ices. Band depth mapping is used to help distinguish between the composition of volatiles and provide a check for the techniques of principal components analysis (PCA) …
Current sheet control of recurrent particle increases at 4-5 AU
Lario, D.; Balogh, A.; Maksimovic, M. +5 more
We examine the relation between the current sheet as derived from observations of the Sun's neutral line, and recurrent particle increases associated with co-rotating interactions regions (CIR) at 4 to 5 AU radial distance as observed by the Ulysses spacecraft during its first out-of-ecliptic orbit around the Sun. We compare observations during th…
Infrared spectroscopy of Nova Cassiopeiae 1993 - III. ISO observations
Eyres, S. P. S.; Salama, A.; Evans, A. +2 more
The [Oiv]lambda25.89 fine-structure line has been detected in Nova Cassiopeiae 1993 (V705 Cas) by the Short Wavelength Spectrometer on the Infrared Space Observatory (ISO). Preliminary analysis using cloudy suggests that oxygen is overabundant relative to solar by at least 25 (by number), and that the abundance of neon is 0.5 x solar at most; the …
The ultraviolet variations of the post-AGB star HD 89353
Parthasarathy, M.; Monier, R.
Based on an analysis of all low resolution spectra of HD 89353 (HR 4049) obtained with the International Ultraviolet Explorer (IUE) over several years and uniformly reprocessed, we report on large ultraviolet variations for this star whose amplitude increases towards long wavelengths. Ultraviolet maximum and minimum occur respectively at phase 0.5…
ISOPHOT observations of narrow line Seyfert 1 galaxies
Polletta, M.; Courvoisier, T. J. -L.
Broad infrared spectra (7-200 mu m) of four NLSy1 galaxies, obtained with the imaging photo-polarimeter (ISOPHOT) on-board ISO, are presented. ISOPHOT data have been analyzed applying a (non standard) method that is described in details. The infrared spectra of the four selected NLSy1 galaxies have been analyzed in order to derive the distribution…