Search Publications
Planetary Camera Observations of NGC 1275: Discovery of a Central Population of Compact Massive Blue Star Clusters
Holtzman, J. A.; Faber, S. M.; Ewald, S. P. +10 more
We have discovered a population of bright blue pointlike sources within 5 kpc of the nucleus of NGC 1275 using HST Planetary Camera observations. The typical object has M_v_ ~ - 12 to - 14 (H_0_ = 75 km s^-1^ Mpc^-1^ ); the brightest has M_v_ ~ - 16. They are all blue, with V - R <~ 0.3. The color distribution and lack of excess Hα emission are…
The ULYSSES solar wind plasma experiment
McComas, D. J.; Goldstein, B. E.; Bame, S. J. +5 more
The scientific objectives of the Ulysses solar wind plasma experiment, termed the Solar Wind Observations Over the Poles of the Sun (SWOOPS) include measurements of the solar-wind global properties, the nonlinear MHD disturbances in the solar wind, the internal state of the solar wind plasma, and the solar-wind interaction with Jupiter's magnetic …
Intrinsic parameters of galactic luminous OB stars.
Butler, K.; Kudritzki, R. P.; Herrero, A. +3 more
We present the results of a spectroscopic analysis of 25 galactic luminous OB stars. The gravities are in general lower than previously assumed, especially for giants. The helium abundances are also higher than normal in many cases. Using data from the spectroscopic analysis, radii, luminosities and masses are derived. The observed wind terminal v…
The magnetic field investigation on the ULYSSES mission - Instrumentation and preliminary scientific results
Balogh, A.; Tsurutani, B. T.; Forsyth, R. J. +5 more
A fundamental feature of the heliosphere is the three-dimensional structure of the interplanetary magnetic field. The magnetic field investigation on Ulysses, the first space probe to explore the out-of-ecliptic and polar heliosphere, aims at determining the large-scale features and gradients of the field, as well as the heliolatitude dependence o…
The Solar Wind Ion Composition Spectrometer
Livi, S.; Balsiger, H.; Geiss, J. +21 more
The Solar Wind Ion Composition Spectrometer (SWICS) on Ulysses is designed to determine uniquely the elemental and ionic-charge composition, and the temperatures and mean speeds of all major solar-wind ions, from H through Fe, at solar wind speeds ranging from 175 km/s (protons) to 1280 km/s (Fe(8+)). The instrument, which covers an energy per cha…
Observations of Highly Ionized Gas in the Galactic Halo
Sembach, Kenneth R.; Savage, Blair D.
A sample of high-quality sight lines is studied by means of IUE spectra to study the formation of Si IV, C IV, and N V in the Galaxy and constrain the mechanisms of halo gas formation. High-dispersion IUE spectra are taken for 12 objects to give combined spectra for studying the halo gas along the sight lines. N V absorption is reported in 10 of t…
An Ionized Accretion Disk in Cygnus X-1
Done, C.; Mulchaey, J. S.; Mushotzky, R. F. +1 more
Results of an analysis of archival Exosat and HEAO 1-A2 observations of Cyg X-1 are presented. It is found, in agreement with Ebisawa (1991), that the X-ray spectrum of Cyg X-1 exhibits a 'high-energy excess' above 8 keV, similar to that seen in Ginga spectra of AGN. It is shown, on the basis of a likelihood ratio test, that the data are significa…
16. A tridimensional model of the galactic interstellar extinction.
Arenou, F.; Gomez, A.; Grenon, M.
The distribution of interstellar extinction has been mapped over the whole sky, using all available spectral and photometric data. The color excess distribution is modelled as a function of galactic latitude, longitude and distance within about 1 kpc from the sun. The model was used to predict the reddened Tycho and Johnson (B-V) colors, with the …
Large amplitude ion-acoustic solitons in a dusty plasma
Shukla, P. K.; Bharuthram, R.
Large amplitude ion-acoustic solitons in a plasma with a finite population of negatively charged dust grains are investigated. The effects of the dust grains on the soliton amplitude and Mach number are examined. It is found that both compressional and rarefactive solitons can occur.
Cometary dust trails I. Survey
Sykes, Mark V.; Walker, Russell G.
Cometary dust trails were first observed by the Infrared Astronomical Satellite and consist of large refractory particles ejected from short-period comets at low velocities. Consequently, they tend to be found near the orbital paths of their parent bodies, their long and narrow appearance reminescent of airplane contrails. An examination of the en…