Search Publications
Propagation of three-dimensional Alfvén waves in a stratified, thermally conducting solar wind
Orlando, S.; Peres, G.; Rosner, R. +1 more
We model the propagation of three-dimensional, adiabatic, linear Alfvén waves in the solar atmosphere and wind, taking into account relevant physical effects, including gravity stratification, thermal conduction, radiative losses, and heating (via a phenomenological term). Our magnetohydrodynamic solar wind model also accounts for the momentum dep…
Hubble Space Telescope Counts of Elliptical Galaxies: Constraints on Cosmological Models?
Driver, Simon P.; Windhorst, Rogier A.; Phillipps, Steven +1 more
The interpretation of galaxy number counts in terms of cosmological models is fraught with difficulty because of uncertainties in the overall galaxy population (mix of morphological types, luminosity functions, etc.) and in the observations (loss of low surface brightness images, image blending, etc.). Many of these can be overcome if we use deep …
Luminosity Evolution in Cluster Galaxies From z=0.41 to z=0.02
Barrientos, L. Felipe; Schade, David; Lopez-Cruz, Omar
HST archive images of the cluster CL 0939+4713 (z = 0.41), together with ground-based images of Coma (z = 0.02), have been used to make a direct comparison of the structural properties of the early-type galaxies in these clusters. This well-matched pair of images has similar rest-frame filter passband, nearly identical resolution in physical units…
Evidence for Supersonic Turbulence in the Upper Atmosphere of Jupiter
Clarke, John T.; Emerich, Claude; Ben Jaffel, Lotfi +4 more
Spectra of the hydrogen Lyman α (Ly-α) emission line profiles of the jovian dayglow, obtained by the Goddard High Resolution Spectrograph on the Hubble Space Telescope, appear complex and variable on time scales of a few minutes. Dramatic changes occur in the Ly-α bulge region at low latitudes, where the line profiles exhibit structures that corre…
ULYSSES observations of open and closed magnetic field lines within a coronal mass ejection.
Balogh, A.; Forsyth, R. J.; Goldstein, B. E. +7 more
During the rapid passage from the Sun's south to north polar regions, the Ulysses spacecraft encountered in February 1995, at 24°S, a coronal mass ejection (CME) exactly at the time when it crossed from high speed solar wind coronal hole flow into low speed streamer belt flows. We have investigated this CME, which was superimposed on an energetic …
MWC 314: a high-luminosity peculiar Be star.
Miroshnichenko, A. S.
New broad-band multicolor photometry and optical spectroscopy of the emission-line star MWC 314= BD +14deg3887 as well as a study of its ultraviolet spectrum are reported. It is shown that the star exhibits photometric variability with a quasi-regular component. Main parameters of the star and its envelope are determined from both the spectral ene…
A Possible X-Ray Counterpart to SGR 1900+14
Hurley, K.; Kouveliotou, C.; Bowyer, S. +9 more
The location of the soft gamma repeater SGR 1900+14 was recently reduced to two ~5 arcmin2 alternate error boxes by the network synthesis method. We have used the ROSAT High Resolution Imager to observe the error box that is closest to the supernova remnant G42.8+0.6. A quiescent, steady, point X-ray source was found at alpha (2000) = 19h07m14.s15…
Study of Time Varitions of UV Continuum and Emission Lines in 3C 390.3
Zheng, Wei
Based on the IUE SWP spectra obtained between 1978 and 1994, the variations of the UV continuum and the Lyα and C IV emission lines of the broad-line radio galaxy 3C 390.3 are studied. The UV continuum between 1220 and 1990 A has varied considerably. In 1991 August, the flux at 1360 A reached a maximum level of 1.3 x 10^14^ erg cm^-2^ s^-1^ A^-1^,…
Flare energetics: analysis of a large flare on YZ Canis Minoris observed simultaneously in the ultraviolet, optical and radio.
Doyle, J. G.; Pagano, I.; Linsky, J. L. +7 more
The results of coordinated observations of the dMe star YZ CMi at optical, UV and radio wavelengths during 3-7 February 1983 are presented. YZ CMi showed repeated optical flaring with the largest flare having a magnitude of 3.8 in the U-band. This flare coincided with an IUE exposure which permits a comparison of the emission measure curves of YZ …
Coronal Gas in the Halo. II. ORFEUS Observations of Galactic Halo Stars
Hurwitz, M.; Bowyer, S.
We present new intermediate-resolution spectra (λ/Δλ = 3300) of fourteen early-type halo stars near the O VI resonance doublet at 1031.93 and 1037.62 These spectra were obtained with the Berkeley extreme and far-ultraviolet (EUV/FUV) spectrometer in the ORFEUS telescope aboard the space platform ASTRO-SPAS during the mission of space shuttle Disco…