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Interplanetary shocks observed by ULYSSES in the ecliptic plane as a function of the heliocentric distance

Balogh, A.; Pantellini, F.; Forsyth, R. J. +5 more

During its mission in the ecliptic plane, the Ulysses spacecraft crossed many heliospheric large-scale structures. Several interplanetary (IP) shocks were identified and characterized using the radio receiver, magnetometer and proton analyser aboard. The spectroscopy of the thermal noise measured by the radio receiver gives the plasma electron den…

Evidence for Mass Outflow from the Nucleus of M101: Knots, Rings, and a Geyser

Geisler, D.; Moody, J. W.; Joner, M. D. +5 more

Hα on-line and off-line CCD images of M101 obtained with the Canada-France-Hawaii 3.6 m telescope show the presence of two Hα bright, filled knots paired linearly across the nucleus in a north-south orientation. The knots are centered 2.4" (85 pc, assuming a distance to M101 of 7.4 Mpc) from the nucleus and lie roughly perpendicular to an east-wes…

A multiwavelength study of the classical nova V4169 Sagittarii.

de Martino, D.; Evans, A.; Rawlings, J. M. C. +8 more

We present multiwavelength observations of V4169 Sgr (Nova Sgr 92#2) from 1000A to 2cm for the first year following visual maximum. V4169 Sgr was an `Fe II' type nova, and evolved from P^0^_fe_ to N_0_ in the Tololo nova classification scheme. The ultraviolet spectrum was very similar to that of nova PW Vul, and the near infra-red spectrum was dom…

The Threshold for Stellar Winds in Hot Main-Sequence Stars

Morrison, Nancy D.; Grigsby, James A.

The profiles of ultraviolet resonance lines of C IV were surveyed in a sample of 29 cluster and association members in the spectral type range O9-B2 III-V, together with a few field stars of interest. The temperatures and gravities of the stars were taken from the model atmosphere analysis by Grigsby, Morrison, & Anderson (1992), and the lumin…

TYCHO astrometry from half of the mission

Makarov, V. V.; Pedersen, H.; Lindegren, L. +8 more

The Hipparcos satellite's star mapper gives photon counts in two spectral channels simultaneously, close to Johnson B and V. The transit times and the signal amplitudes for each star across two groups of four slits are derived and used for astrometry and photometry, respectively, and this constitutes the Tycho project. The present paper describes …

Long-term Cosmic-Ray Modulation along the Ulysses Trajectory: A Numerical Simulation

Wibberenz, G.; Potgieter, M. S.; Haasbroek, L. J.

The Ultraviolet Spectrum of the Gravitational Lens Candidate UM 425 = QSO 1120+019: Evidence for Broad Absorption Line (BAL) Structure

Michalitsianos, A. G.; Oliversen, R. J.

The UV line profile structure of high-ionization resonance lines found with the International Ultraviolet Explorer (IUE) in the brightest of four multiply imaged sources (image-A) in the `candidate gravitational lens UM 425 = QSO 1120+019 indicates broad absorption line (BAL) structure. The deep-broad trough associated with the O VI line extends t…

ROSAT pointed observations of four X-ray bright DA white dwarfs.

Reimers, D.; Wolff, B.; Jordan, S. +1 more

We present pointed observations of four hot DA white dwarfs with the ROSAT satellite. Measurements with the Position Sensitive Proportional Counter (PSPC) and the Wide Field Camera (WFC) were analyzed in the framework of pure hydrogen model atmospheres. The results fit well into the picture of previous studies that objects between about 20000 and …

Electron-impact ionization of interstellar hydrogen and helium at interplanetary shocks

Isenberg, Philip A.; Feldman, William C.

We investigate the ionization of interstellar hydrogen and helium due to electron impact by shock-heated electrons. Taking the electron distributions measured at four interplanetary shocks at 1 AU, we show that the electrons in the downstream region of strong shocks can ionize interstellar atoms at rates matching or exceeding the nominal photoioni…

Potential flow downstream of the heliospheric terminal shock: A non-spherical shock

Suess, S. T.; Nerney, Steven

We have solved for the potential flow down-stream of the terminal shock of the solar wind in the limit of small departures from a spherical shock due to a latitudinal ram pressure variation in the supersonic solar wind. The solution connects anisotropic streamlines at the shock to uniform streamlines down the heliotail because we use a non-slip bo…