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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 709834.0, MPI für Astronomie / Publikationen_mpia
Orbital and physical parameters of eclipsing binaries from the All-Sky Automated Survey catalogue. VI. AK Fornacis: a rare, bright K-type eclipsing binary
Authors:Helminiak, K. G.; Brahm, R.; Ratajczak, M.; Espinoza, N.; Jordán, A.; Konacki, M.; Rabus, M.
Date of Publication (YYYY-MM-DD):2014
Title of Journal:Astronomy and Astrophysics
Start Page:id. A64 (9 pp)
Audience:Not Specified
Abstract / Description:<BR /> Aims: We present the results of the combined photometric and spectroscopic analysis of a bright (V = 9.14), close (d = 31 pc), late-type detached eclipsing binary, <ASTROBJ>AK Fornacis</ASTROBJ>. This P = 3.981 d system has not been previously recognised as a double-lined spectroscopic binary, and this is the first full physical model of this unique target. <BR /> Methods: With the FEROS, CORALIE, and HARPS spectrographs, we collected a number of high-resolution spectra to calculate radial velocities of both components of the binary. Measurements were done with our own disentangling procedure and the TODCOR technique, and were later combined with the photometry from the ASAS and SuperWASP archives. We also performed an atmospheric analysis of the component spectra with the Spectroscopy Made Easy package. <BR /> Results: Our analysis shows that AK For consists of two active, cool dwarfs having masses of M1 = 0.6958 ± 0.0010 and M2 = 0.6355 ± 0.0007 M&sun; and radii of R1 = 0.687 ± 0.020 and R2 = 0.609 ± 0.016 R&sun;, respectively, which are slightly less metal-abundant than the Sun. Parameters of both components are well reproduced by the models. <BR /> Conclusions: AK For is the brightest system among the known eclipsing binaries with K- or M-type stars. Its orbital period is one of the longest, and its rotational velocities is one of the lowest, which allows us to obtain very precise radial velocity measurements. The precision in physical parameters that we obtained places AK For among the binaries with the best mass measurements in the literature. It also fills the gap in our knowledge of stars in the range of 0.5-0.8 M&sun; and between short and long-period systems. All this makes AK For a unique benchmark for understanding the properties of low-mass stars. Based on observations collected at the European Southern Observatory, Chile under programmes 088.D-0080, 089.D-0097, 089.C-0415, 090.C-0280 and 090.D-0061 and through CNTAC proposals CN-2012A-21 and CN-2013A-93.
Free Keywords:binaries: eclipsing; binaries: spectroscopic; stars: fundamental parameters; stars: individual: AK Fornacis
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:ISSN:0004-6361 %R 10.1051/0004-6361/201220985
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