Search Publications

Toward the HIPPARCOS link: astrometry of stars and extragalactic sources in the field of the spiral galaxy M51.

Brosche, P.; Odenkirchen, M.

We present absolute proper motions of 14 Hipparcos stars from ground based photographic astrometry in a 2x2deg field around the spiral galaxy Messier 51. These are part of a catalogue of 340 stars with B<=16, for which positions, proper motions, and B magnitudes have been derived from a series of 16 photographic plates. Due to large epoch diffe…

A Search for Stellar Flares in Gamma-Ray Bursts Observed by BATSE and ULYSSES

Hurley, K.; Fishman, G. J.; Kouveliotou, C. +2 more

We have searched for gamma-ray bursts during stellar flares using Ulysses and BATSE/CGRO data and for a correlation between flare star positions and burst positions. More than 3000 stellar flares have been identified optically, but neither BATSE nor Ulysses observed any gamma-ray bursts which could be attributed to them. Using the BATSE trigger th…

Variations of the High Energy Electron Flux Along the ULYSSES Trajectory

Sierks, H.; Kunow, H.; Wibberenz, G. +7 more

We describe for the first time the analysis of high energy electrons (above 240 MeV) from the COSPIN/KET experiment onboard Ulysses. The electron time profiles in four energy windows are presented from Oct. 90 to the end of March 94, up to a maximum heliographic latitude of 57 °S. The recovery rates we derived for the electrons are compared to the…

Radio Occultation Studies with Solar Corona Sounders

Pätzold, M.; Neubauer, F. M.; Bird, M. K.

Solar Corona Sounders (SCS), a mission designed to utilize the radio occultation technique for investigations of the inner heliosphere, was submitted to ESA in response to a call for new mission concepts. The SCS platforms are two small multifrequency transmitters placed at the “anti-Earth” position (superior solar conjunction) for continuous radi…

Evolution of the Electron/Proton Ratios Between 1 and 7 GV Measured at Ulysses, as a Function of Time and Latitude

Sierks, H.; Kunow, H.; Wibberenz, G. +10 more

A photoionization model of the nebula around the WC11 star M4-18

Rao, N. Kameswara; Surendiranath, R.

A photoionization code has been developed incorporating provision for the presence of dust mixed with gas. M4-18 has been modelled utilizing optical CCD spectra and other observations ranging from UV to radio wavelengths. T_e and N_e from the model are 6600K and 6050 cm^-3, respectively. The abundances of C, N and Ne are found to be the same as th…

Radiation Hydrodynamic Models of Eclipsing Low-Mass X-Ray Binaries

McKee, Christopher F.; Murray, Stephen D.; Woods, D. Tod +2 more

We present the results of self-consistent two-dimensional radiation hydrodynamic models of winds and coronae above accretion disks in low-mass X-ray binaries. The numerical method combines adaptive mesh refinement for the hydrodynamics with combined ray tracking/flux-limited diffusion for the radiation. The results of the models are compared with …

Tomography/Power Spectrum Techniques for Removal of Fixed Pattern Noise from Hubble Space Telescope Spectra

Smith, Andrew M.; Bruhweiler, Frederick C.; Lyu, Cheng-Hsuan

We have developed tomography/power spectrum algorithms to differentiate the intrinsic stellar spectrum from the pronounced fluctuations in the spectrum counts due to photocathode granularity and diode-to-diode gain variations. We have presented the results of four typical high signal-to-noise (S/N) and high-resolution data sets, obtained from the …

A particle event at 5 AU and 20° southern latitude from measurements with the EPAC instrument on Ulysses

Krupp, N.; Fränz, M.; Balogh, A. +9 more

In November 1992, the Ulysses spacecraft observed a multiple solar particle event and a CME event at 5.2 AU and a heliographic latitude of 20° S which were superimposed to the recurrent corotating interacting region. Distinct particle flux increases caused by these events were observed in all energy channels of the EPAC experiment. The experimenta…

Interaction Between Whistler-Mode Waves and Electrons in the Vicinity of Interplanetary Shocks as Seen by Ulysses: A Preliminary Study

Balogh, A.; Forsyth, R. J.; Bame, S. J. +5 more

We present a study of wave particle interaction in the vicinity of interplanetary shocks in the ecliptic plane, as observed by the Ulysses spacecraft. We focus here on some events, for which electromagnetic waves are observed, mainly down-stream of the shock. The whistler mode waves are studied by means of the Unified RAdio and Plasma wave experim…