Search Publications
Large amplitude IMF fluctuations in corotating interaction regions: Ulysses at midlatitudes
Tsurutani, Bruce T.; Goldstein, Bruce E.; Balogh, Andre +2 more
Corotating Interaction Regions (CIRs), formed by high-speed corotating streams interacting with slow speed streams, have been examined from -20° to -36° heliolatitudes. The high-speed streams emanate from a polar coronal hole that Ulysses eventually becomes fully embedded in as it travels towards the south pole. We find that the trailing portion o…
The albedo spectrum of Europa from 2200 Å to 3300 Å
Weaver, H. A.; Noll, Keith S.; Gonnella, A. M.
We obtained a spectrum of Europa from 2224 to 3302 Å with high signal to noise and a resolution of 6.3 Å with the Hubble space telescope faint object spectrograph. We detect a broad absorption feature centered at 2800 Å, seen previously at lower signal to noise in International Ultraviolet Explorer spectra of Europa. No additional absorption featu…
Ultraviolet Observations of SN 1987A with the IUE Satellite
Pun, Chun S. J.; Cassatella, Angelo; Gilmozzi, Roberto +12 more
Ultraviolet (λ: 1150-3300 A) observations of SN 1987A with the IUE satellite provide a unique data set. Observations started the day after discovery, 1987 February 24 (day 1.6), and a total of 751 spectra were obtained through 1992 June 9 (day 1567). The data have been processed to generate a complete catalog of SN 1987A ultraviolet spectra. The d…
Hubble Space Telescope Observations of White Dwarfs in the Globular Cluster M4
Bond, Howard E.; Ibata, Rodrigo A.; Stetson, Peter B. +9 more
With the Wide Field Planetary Camera 2 (WFPC2) on the Hubble Space Telescope, we have discovered in M4 (NGC 6121, C1620-264) the first extensive sequence of cooling white dwarfs seen in a globular cluster. Adopting a distance modulus of (m - M)V = 12.65 and a reddening of E(B - V) = 0.37, we show that the sequence, which extends over 9 < MU <…
MG 0414+0534: A Dusty Gravitational Lens
Lawrence, C. R.; Elston, Richard; Turner, E. L. +1 more
The gravitational lens system MG 0414+0534 has an unexceptional four- image lensing geometry; however, the optical counterparts of the radio images are exceedingly red, with spectra unlike that of any previously observed active nucleus. New infrared spectra reveal broad Balmer lines at a redshift of 2.639+/-0.002. We use these spectra, in combinat…
Corotating Variations of Cosmic Rays Near the South Heliospheric Pole
Jokipii, J. R.; Kota, J.
Three-dimensional simulations of the heliospheric modulation of galactic cosmic ray protons show that corotating variations in the intensity can persist to quite high heliographic latitudes. Variations are seen at latitudes considerably higher than the maximum latitude extension of the heliographic current sheet, in regions where the solar wind ve…
ROSAT observations of γ Velorum (WC8+O9I). I. The discovery of colliding-wind X-ray emission.
Willis, A. J.; Schild, H.; Stevens, I. R.
We present an analysis of 13 X-ray (0.1-2.5keV) observations of γ Velorum obtained with the XRT+PSPC on the ROSAT satellite. The first set of 10 observations were obtained in our Guest Observer AO2 programme, with 9 at roughly 8-day intervals in the 78^d^.5 binary period, providing nearly complete phase coverage. Of these, the last two (secured at…
Identification of faint radio sources with optically luminous interacting disk galaxies
Griffiths, R. E.; Fomalont, E. B.; Windhorst, R. A. +5 more
THE question of when galaxies and stars started to form in the early Universe is one of the most fundamental in cosmology. Faint radio sources (with fluxes of a few microjanskys or less) may be these early galaxies; radio surveys have shown them to be increasingly common as fainter levels are reached1-7, suggesting that they are an impo…
Composition of Interstellar Clouds in the Disk and Halo. III. HD 149881
Fitzpatrick, Edward L.; Spitzer, Lyman, Jr.
The spectrum of HD 149881, a halo star 1300 pc above the Galactic plane, has been analyzed, based on high-resolution GHRS data from Hubble Space Telescope (HST) together with 21 cm emission observations and profiles of Na I and Ca II features. The results reveal 11 absorption components, of which nine are produced in H I regions, with log N(H…
Ellipticals with Kinematically Distinct Cores: WFPC1 Imaging of Nearby Ellipticals
Franx, Marijn; Illingworth, Garth D.; Forbes, Duncan A.
Ground-based spectroscopy of nearby ellipticals has revealed many to have cores that are kinematically distinct from the rest of the galaxy. Spectroscopic line analysis suggests that these kinematically distinct cores form a disk-like structure. A variety of mechanisms have been proposed to explain such cores. Here we present high resolution WFPC1…