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Hubble Space Telescope Fine Guidance Sensor Astrometry of the Low-Mass Binary L722-22

Hershey, John L.; Taff, L. G.

The M dwarf star L722-22 (LHS 1047, GJ 1005) was discovered to be a binary in 1979. Analysis of ground-based data indicated a mass near 0.06 M_⊙ for the secondary star, well below the nominal stellar mass limit of 0.08 M_⊙. The close, faint binary was near the limit for ground-based astrometry and was approved for Hubble Space Telescope Fine Guida…

Discovery of a new 170 S X-ray pulsar 1SAX J1324.4-6200

Parmar, A. N.; Mineo, T.; Angelini, L. +2 more

We report the discovery with BeppoSAX of a new 170.84 +/- 0.04 s X-ray pulsar, XB 1323-619b, found serendipitously in the field of the X-ray binary XB 1323-619 in 1997 August. The source and periodicity are also detected in archival ASCA data taken in 1994. The X-ray spectrum is modeled by a power-law with a photon index of 1.0 +/- 0.4 and absorpt…

Spatial Interpolation for Four Spacecraft: Theory

Chanteur, Gérard

Multiplicity among peculiar A stars. I. The AP stars HD 8441 and HD 137909, and the AM stars HD 43478 and HD 96391

Carrier, F.; Udry, S.; North, P. +2 more

We present the first results of a radial-velocity survey of cool Ap and Am stars. HD 8441 is not only a double system with P = 106.357 days, but is a triple one, the third companion having an orbital period larger than 5000 days. Improved orbital elements are given for the classical Ap star HD 137909 = beta CrB by combining our radial velocities w…

The symmetry of the heliospheric current sheet as observed by Ulysses during the Fast Latitude Scan

Balogh, André; Erdős, Géza

The position of the heliospheric current sheet is investigated, based on Ulysses observations during the fast latitude scan from the South pole (in September, 1994) to the North pole (in July, 1995). The location of the current sheet on the source surface was calculated by mapping back the magnetic field vectors measured by Ulysses along the solar…

Spatially resolved optical spectroscopy of the Herbig Ae/Vega-like binary star HD 35187

Crawford, I. A.; Dunkin, S. K.

We report on observations of the young binary system HD 35187 (SAO 77144). For the first time, we have obtained spatially resolved optical spectra of the individual stars. Analysis of their effective temperatures indicates that the stars have spectral types of A2 (HD 35187B) and A7 (HD 35187A). Analysis of the Hγ Balmer line indicates a luminosity…

Analyzing short-term X-ray variability of Cygnus X-1 with Linear State Space Models

Pottschmidt, Katja; Wilms, Joern; Koenig, Michael +1 more

Cyg X-1 exhibits irregular X-ray variability on all measured timescales. The usually applied shot noise models describe the typical short-term behavior of this source by superposition of randomly occuring shots with a distribution of shot durations. We have reanalyzed EXOSAT ME observations of Cyg X-1\ using the more general Linear State Space Mod…

Recurrent Solar Modulation of the Galactic Cosmic Rays and the Anomalous Nuclear Component in Three Dimensions of the Heliosphere

Simpson, J. A.

Ulysses Mission investigations, extending from pole-to-pole of the Sun and inner heliosphere in the period 1993-1996, have led to discoveries that will change dramatically models to account for the physical phenomena underlying the 26-day modulation of galactic cosmic rays and anomalous nuclear components and their propagation modes. These new fin…

Numerical simulation of observations with GOLF on board SOHO

Roca Cortes, T.; Garcia, R. A.; Regulo, C.

The main objective of the GOLF Experiment (Global Oscillations at Low Frequencies) on-board the SOHO (Solar and Heliospheric Observatory) space mission is the quantitative knowledge of the internal structure of the Sun by measuring the spectrum of its global oscillations in a wide frequency range (30 nHz to 6 mHz). There is special interest in det…

A comparison of the fast timing behaviour of 4U 1705-44 to that of 4U 1608-52 and Cygnus X-1

van der Klis, M.; Berger, M.

We studied the fast timing behaviour of the atoll source \leavevmode4U 1705-44 using the entire \mboxEXOSAT dataset, four observations covering a total of 230 000 seconds of 1-20 keV spectral and timing data. In one of the observations, \leavevmode4U 1705-44 was in a low intensity ``island'' state and had an unusually hard spectrum. The fast timin…