Parameters of the eclipsing binary α Draconis observed by TESS and SONG

Hey, Daniel R. and Kochoska, Angela and Monier, Richard and Kochukhov, Oleg and Johnston, Cole and Bedding, Timothy R. and Murphy, Simon J. and Abdul-Masih, Michael and Southworth, John and Andersen, Mads Fredslund and Grundahl, Frank and Palle, Pere L. (2022) Parameters of the eclipsing binary α Draconis observed by TESS and SONG. Monthly Notices of the Royal Astronomical Society, 511 (2). pp. 2648-2658. ISSN 0035-8711

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We present an analysis of the eclipsing single-lined spectroscopic binary system α Dra based on photometry from the Transiting Exoplanet Survey Satellite (TESS) mission and newly acquired spectroscopic measurements. Recently discovered to have eclipses in the TESS data, at a magnitude of V = 3.7, α Dra is now one of the brightest detached eclipsing binary (EB) systems known. We obtain the parameters of this system by simultaneously fitting the TESS light curve in conjunction with radial velocities (RVs) acquired from the SONG spectrograph. We determine the fractional radii (R/a) for the primary and secondary components of the system to be 0.0479 ± 0.0003 and 0.0226 ± 0.0005, respectively. We constrain the temperature, mass, and luminosity (log(L/L⊙)) of the primary to be 9975±125 K, 3.7±0.1 M⊙, and 2.49±0.02⁠, respectively, using isochrone fitting. Although the secondary is too faint to appear in the spectra, the obtained mass function and observed inclination yields a secondary minimum mass of M2=2.5±0.1 M⊙, which suggests that it is an A2V type star. We were unable to obtain RVs of the secondary, and are only able to see a weak highly rotationally broadened absorption line, indicating that the secondary is rapidly rotating (vsin i ∼ 200 km s−1). We also perform an abundance analysis of the primary star for 21 chemical elements. We find a complex abundance pattern, with a few elements having mild underabundances while the majority have solar abundances. We make available the PYTHON code used in this paper to facilitate future modelling of EBs.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: File reproduced in accordance with the copyright policy of the publisher/author.
Faculty/School / Institute/Centre: No Faculty
Faculty/School / Institute/Centre: No Faculty
Date Deposited: 17 Jul 2022 23:25
Last Modified: 27 Sep 2022 04:12
Uncontrolled Keywords: binaries: eclipsing; stars: chemically peculiar; stars: fundamental parameters
Fields of Research (2020): 51 PHYSICAL SCIENCES > 5101 Astronomical sciences > 510109 Stellar astronomy and planetary systems
Socio-Economic Objectives (2020): 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280120 Expanding knowledge in the physical sciences
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