Analysis of δ Librae including Hipparcos astrometry
Abstract
New spectroscopy of the classical Algol system δ Lib, combined with high-quality optical and infrared photometry, provides the basis for a good understanding of the close binary system's main parameters. Detailed analysis of the photometry reveals the significant role of a third light source, pointing to the existence of a companion to the eclipsing system of mass ~1Msolar.
We review the methodology of applying high-accuracy positional information, available from the Hipparcos Intermediate Astrometric Data archive, to stars that may have such companions. Analysis of the astrometry of δ Lib also points to a third star similar to the one already identified by Worek from radial-velocity data, although with slightly revised parameters. O-C data do not contradict this, but their general precision (while confirming the close pair's Algol status) fails to allow a decision on the third orbit parameters: Worek's or revised ones. Taking the photometry, spectroscopy and astrometry together, however, the existence of a third star of comparable mass to the Sun, as a relatively close companion to the eclipsing binary (~4 au), is confirmed.- Publication:
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Monthly Notices of the Royal Astronomical Society
- Pub Date:
- August 2006
- DOI:
- 10.1111/j.1365-2966.2006.10619.x
- Bibcode:
- 2006MNRAS.370.1935B
- Keywords:
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- binaries: close: stars: individual: δ Lib;
- binaries: close;
- stars: individual: δ Lib