J/A+A/558/A71 Times of minima for 1SWASP J234401.81-212229.1 (Lohr+, 2013)
One, two or three stars? An investigation of an unusual eclipsing binary
candidate undergoing dramatic period changes.
Lohr M.E., Norton A.J., Kolb U.C., Boyd D.R.S.
<Astron. Astrophys. 558, A71 (2013)>
=2013A&A...558A..71L 2013A&A...558A..71L
ADC_Keywords: Binaries, eclipsing ; Stars, variable ; Ephemerides
Keywords: stars: individual: 1SWASP J234401.81-212229.1 -
stars: variables: general - binaries: close - binaries: eclipsing
Abstract:
We report our investigation of 1SWASP J234401.81-212229.1, a variable
with a 18461.6s period. After identification in a 2011 search of the
SuperWASP archive for main-sequence eclipsing binary candidates near
the distribution's short-period limit of ∼0.20d, it was measured to be
undergoing rapid period decrease in our earlier work, though later
observations supported a cyclic variation in period length.
Spectroscopic data obtained in 2012 with the Southern African Large
Telescope did not, however, support the interpretation of the object
as a normal eclipsing binary. Here, we consider three possible
explanations consistent with the data: a single-star oblique rotator
model in which variability results from stable cool spots on opposite
magnetic poles; a two-star model in which the secondary is a brown
dwarf; and a three-star model involving a low-mass eclipsing binary in
a hierarchical triple system. We conclude that the latter is the most
likely model.
Description:
Times of light curve primary minima for 1SWASP J234401.81-212229.1 are
presented here, as determined from SuperWASP archive data by an IDL
program described in Lohr et al. (2013A&A...549A..86L 2013A&A...549A..86L). For each
minimum, an epoch (cycle) number is given, relative to a zero point
determined near the middle of the SuperWASP light curve data set;
heliocentric Julian dates and uncertainties in timing are also
included.
Objects:
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RA (2000) DE Designation(s)
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23 44 01.81 -21 22 29.1 1SWASP J234401.81-212229.1 = StKM 1-2148
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
minima.dat 27 267 Times of minima
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Byte-by-byte Description of file: minima.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- E [-2461/8793] Cycle number (epoch) of minimum
7- 19 F13.5 d HJD Heliocentric Julian date of minimum
21- 27 F7.5 d e_HJD Uncertainty in time of minimum
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Acknowledgements:
Marcus Lohr, Marcus.Lohr(at)open.ac.uk
(End) Marcus Lohr [OU, UK], Patricia Vannier [CDS] 06-Sep-2013