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Absolute measurements of trigonometric parallaxes with astrometric satellites

Makarov, V. V.

The concept of absolute trigonometric parallax measurements is formulated in strict mathematical terms, in connection with the widely discussed plans for a future astrometric space mission. The parallaxes determined for a large number of stars spread all over the sky are absolute if the expected error (accidental or systematic) of the zero-point, …

HIP 60350: an extreme runaway star

Paunzen, E.; Maitzen, H. M.; Wagner, R. M. +2 more

Using Hipparcos proper motion as well as published and our own radial velocity data we identify HIP 60350 as fastest young B-type runaway star ejected 20 Myr ago or slightly less from the galactic plane, probably at a distance from the galactic center corresponding to spiral arm -II. Both the LSR velocity (417 kms(-1) ) and the mass of the star po…

Spectroscopic binary orbits from ultraviolet radial velocities. Paper 29: V Puppis (HD 65818)

Stickland, D. J.; Lloyd, C.; Pachoulakis, I. +1 more

ORFEUS-SPAS II Observations of the Ultraviolet-bright Star Barnard 29 in M13

Hurwitz, Mark; Dixon, W. Van Dyke

The UV-bright star Barnard 29 in the globular cluster M13 was observed with the Berkeley spectrometer on the ORFEUS-SPAS II mission in 1996 November-December. The resulting spectrum extends from the interstellar cutoff at 912 A to ~1200 A at a resolution of ~0.33 A. It shows numerous absorption features, both photospheric and interstellar, but no …

Shape of the heliospheric termination shock: Effects of latitude variations of solar wind dynamic pressure

Barnes, Aaron

We investigate the consequences of internal solar wind latitude variations on the heliospheric termination shock and the flow of the gas beyond the shock. We have developed a simple gasdynamic model, assuming the solar wind to be a steady, axially symmetric radial outflow of gas that passes through a termination shock and flows incompressibly beyo…

Tetrahedron Geometric Factors

Robert, Patrick; Glassmeier, Karl-Heinz; Daly, Patrick W. +3 more

The Cassini Ion Mass Spectrometer

McComas, D. J.; Young, D. T.; Berthelier, J. -J. +2 more

The joint NASA/European Space Agency Cassini mission to Saturn will carry the Cassini Plasma Spectrometer (CAPS). This instrument consists of three sensors, including the Ion Mass Spectrometer (IMS), a data processing unit, and an actuator that rotates CAPS in order to view a large fraction of the space environment. The IMS makes high sensitivity,…

On the differential ion velocity in the inner solar corona and the observed solar wind ionic charge states

Gloeckler, George; Geiss, Johannes; Ko, Yuan-Kuen

Theoretical calculations on multifluid solar wind have indicated that the velocities of ions of the same element are not the same in the inner coronal region where the freeze-in process of these solar wind heavy ions occurs. This may have nonnegligible effect on the inference of the electron temperature in this region from the observed ionic charg…

Correlation of the HIPPARCOS and Allegheny Observatory Parallax Catalogs

Gatewood, George; Kiewiet de Jonge, Joost; Persinger, Timothy

No significant difference is found between the systems of the Hipparcos and Allegheny Observatory MAP parallax catalogs. The correlation of the parallaxes of 63 stars common to both programs is 0.9995 +/- 0.0001, with an average standard deviation of the difference of 0.0023". While there is no indication of systematic difference in the two progra…

Composition and Opacity in the Solar Interior

Turck-Chieze, Sylvaine

Detailed abundances of elements from hydrogen up to iron are necessary to perform a precise model of the solar structure. Most of them have been deduced from photospheric observed values, some others from the meteoritic composition. Nowadays, thanks to helioseismic constraints, they seem more and more under control.