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Astrometric Radial Velocities From Hipparcos

Published online by Cambridge University Press:  14 August 2015

D. Dravins ,
L. Lindegren ,
S. Madsen  and
J. Holmberg
D. Dravins
Affiliation:
1 Lund Observatory, Box A3, SE-22100 Lund, Sweden
L. Lindegren
Affiliation:
1 Lund Observatory, Box A3, SE-22100 Lund, Sweden
S. Madsen
Affiliation:
1 Lund Observatory, Box A3, SE-22100 Lund, Sweden 2 Copenhagen University Observatory, J. Maries Vej 30, 2100 Copenhagen, Denmark
J. Holmberg
Affiliation:
1 Lund Observatory, Box A3, SE-22100 Lund, Sweden

Abstract

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Space astrometry now permits accurate determinations of stellar radial motion, without using spectroscopy. Although the feasibility of deducing astrometric radial velocities from geometric projection effects was realized already by Schlesinger (1917), only with Hipparcos has it become practical. Such a program has now been carried out for the moving clusters of Ursa Major, Hyades, and Coma Berenices. Realized inaccuracies reach about 300 m/s (Dravins et al. 1997).

Discrepancies between astrometric and spectroscopic radial velocities reveal effects (other than stellar motion) that affect wavelength positions of spectral lines. Such are caused by stellar surface convection, and by gravitational redshifts. A parallel program (Gullberg & Dravins 1997) is analyzing high-precision spectroscopic radial velocities for different spectral lines in these stars, using the ELODIE radial-velocity instrument atHaute-Provence.

Type
II. Joint Discussions
Information
Highlights of Astronomy , Volume 11 , Issue 1: Highlights of Astronomy. As presented at the XXIIIrd General Assembly of the IAU (Part A), 1997 , 1998 , pp. 564
Copyright
Copyright © Kluwer 1998

References

Dravins, D., Lindegren, L., Madsen, S., Holmberg, J. (1997) ESA SP-402. p. 733 Google Scholar
Gullberg, D., Dravins, D. (1997) Highlights of Astronomy 11 (this volume)Google Scholar
Schlesinger, F. (1917) AJ 30, 137 Google Scholar
Further project description: http://www.astro.lu.se/~dainis/ Google Scholar