J/A+A/557/A119 Eclipsing binary system LL Aquarii (Southworth, 2013)
The solar-type eclipsing binary system LL Aquarii.
Southworth J.
<Astron. Astrophys. 557, A119 (2013)>
=2013A&A...557A.119S 2013A&A...557A.119S
ADC_Keywords: Binaries, eclipsing ; Planets ; Photometry
Keywords: stars: fundamental parameters - binaries: eclipsing -
binaries: spectroscopic
Abstract:
The eclipsing binary LL Aqr consists of two late-type stars in an
eccentric orbit with a period of 20.17d. 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±0.009M☉ and a
radius of 1.305±0.007R☉. The secondary star is an analogue of
the Sun, with a mass and radius of 1.014±0.006M☉ and
0.990±0.008R☉ respectively. The system shows no signs of stellar
activity: the upper limit on spot-induced rotational modulation is
3mmag, 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 2.5Gyr. 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.
Description:
A light curve of LL Aqr is presented. The data were obtained by the
SuperWASP survey using both the northern (ORM, La Palma) and southern
(SAAO, South Africa) installations, through a wide filter
approximately the sum of the Gunn g+r passbands. An echelle spectrum
is also presented, obtained from the Hamilton spectrograph on the 3m
Shane telescope at Lick, California, US.
Objects:
-----------------------------------------------
RA (2000) DE Designation(s)
-----------------------------------------------
22 34 42.15 -03 35 58.2 LL Aqr = HD 213896
-----------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
wasplc.dat 36 25056 SuperWASP light curve
spectrum.dat 20 205943 Echelle spectrum
--------------------------------------------------------------------------------
Byte-by-byte Description of file: wasplc.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Camera [141/223] Internal identification number
of camera used
6- 19 F14.6 d HJD Time of midpoint of observation in HJD(UTC)
21- 28 F8.4 mag dmag Differential g+r band magnitude of LL Aqr
31- 36 F6.4 mag e_dmag Measurement error of dmag
--------------------------------------------------------------------------------
Byte-by-byte Description of file: spectrum.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Order [1/89] Echelle order of the flux measurement
5- 13 F9.4 0.1nm lambda [3830/9586] Wavelength of flux measurement
15- 20 F6.1 ct Flux Extracted spectrum flux at this wavelength
--------------------------------------------------------------------------------
Acknowledgements:
John Southworth, astro.js(at)keele.ac.uk
(End) John Southworth [Keele Univ., UK], Patricia Vannier [CDS] 09-Aug-2013