Open AccessAnalysis of δ Librae including Hipparcos astrometry
Author(s) -
Bakış V.,
Budding E.,
Erdem A.,
Bakış H.,
Demircan O.,
Hadrava P.
Publication year - 2006
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2006.10619.x
Subject(s) - astrometry , physics , photometry (optics) , astrophysics , astronomy , stars , binary number , radial velocity , binary star , spectroscopy , arithmetic , mathematics
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 ∼1 M ⊙ . 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.