The solar-type eclipsing binary system LL Aquarii

Southworth, J.

Abstract

The eclipsing binary LL Aqr consists of two late-type stars in an eccentric orbit with a period of 20.17 d. We use an extensive light curve from the SuperWASP survey augmented by published radial velocities and UBV light curves to measure the physical properties of the system. The primary star has a mass of 1.167 ± 0.009 M⊙ and a radius of 1.305 ± 0.007 R⊙. The secondary star is an analogue of the Sun, with a mass and radius of 1.014 ± 0.006 M⊙ and 0.990 ± 0.008 R⊙ respectively. The system shows no signs of stellar activity: the upper limit on spot-induced rotational modulation is 3 mmag, it is slowly rotating, has not been detected at X-ray wavelengths, and the calcium H and K lines exhibit no emission. Theoretical stellar models provide a good match to its properties for a sub-solar metal abundance of Z = 0.008 and an age of 2.5 Gyr. Most low-mass eclipsing binary systems are found to have radii larger than expected from theoretical predictions, blamed on tidally-enhanced magnetic fields in these short-period systems. The properties of LL Aqr support this scenario: it exhibits negligible tidal effects, shows no signs of magnetic activity, and matches theoretical models well.

Citation

Southworth, J. (2013). The solar-type eclipsing binary system LL Aquarii. Astronomy & Astrophysics, 557, Article A119. https://doi.org/10.1051/0004-6361/201322195

• Journal Article Type: Article
• Acceptance Date: Aug 6, 2013
• Online Publication Date: Sep 18, 2013
• Publication Date: 2013-09
• Deposit Date: Jun 16, 2023
• Journal: Astronomy & Astrophysics
• Print ISSN: 0004-6361
• Electronic ISSN: 1432-0746
• Publisher: EDP Sciences
• Peer Reviewed: Peer Reviewed
• Volume: 557
• Article Number: A119
• DOI: https://doi.org/10.1051/0004-6361/201322195
• Keywords: Space and Planetary Science; Astronomy and Astrophysics; stars: fundamental parameters; binaries: eclipsing; binaries: spectroscopic