J/A+A/672/A176 Mass-ratio distribution of contact binary stars (Pesta+, 2023)
Mass-ratio distribution of contact binary stars.
Pesta M., Pejcha O.
<Astron. Astrophys. 672, A176 (2023)>
=2023A&A...672A.176P 2023A&A...672A.176P (SIMBAD/NED BibCode)
ADC_Keywords: Binaries, eclipsing ; Models ; Photometry ; Optical
Keywords: stars: evolution - binaries: close - methods: statistical
Abstract:
The mass ratio q of a contact binary star evolves due to mass
transfer, magnetic braking, and thermal relaxation oscillations to
small values until it crosses a critical threshold qmin. When that
happens, the binary undergoes the tidal Darwin instability, leading to
a rapid coalescence of the components and observable brightening of
the system. So far, the distribution of $q$ has not been measured on a
sufficiently large population of contact binary stars, because the
determination of q for a single contact binary usually requires
spectroscopy. But as was shown previously, it is possible to infer the
mass-ratio distribution of the entire population of contact binaries
from the observed distribution of their light curve amplitudes.
Employing Bayesian inference, we obtain a sample of contact binary
candidates from the Kepler Eclipsing Binary Catalog combined with data
from Gaia and estimates of effective temperatures. We assign to each
candidate a probability of being a contact binary of either late or
early type. Overall, our sample includes about 300 late-type and 200
early-type contact binary candidates. We model the amplitude
distribution assuming that mass ratios are described by a power law
with an exponent $b$ and a cut off at qmin. We find
qmin=0.087+0.024-0.015 for late-type contact binaries with
periods longer than 0.3 days. For late-type binaries with shorter
periods, we find qmin=0.246+0.029-0.046, but the sample is
small. For early type contact binary stars with periods shorter than 1
day, we obtain qmin=0.030+0.018-0.022. These results indicate a
dependence of qmin on the structure of the components and are
broadly compatible with previous theoretical predictions. We do not
find any clear trends in b. Our method can be easily extended to large
samples of contact binaries from TESS and other space-based surveys.
Description:
We present a table of contact binary candidates in the Kepler
Eclipsing Binary Catalog. The table contains the photometric
amplitude, photometric amplitude uncertainty, probability of being a
contact binary of late type, and probability of being a contact binary
of early type for each candidate in the catalog.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 41 2172 Contact binary candidates in the
Kepler Eclipsing Binary Catalog
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See also:
IV/34 : K2 Ecliptic Plane Input Catalog (EPIC) (Huber+, 2017)
J/AJ/151/68 : Kepler Eclipsing Binary Catalog - Third Revision
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 9 I9 --- KIC/EPIC Kepler Input Catalog ID/Ecliptic Plane Input
Catalog ID (1)
11- 18 F8.6 mag Amp Photometric amplitude
20- 27 F8.6 mag e_Amp ? Photometric amplitude uncertainty
29- 34 F6.4 --- ProbLate Probability of being a contact binary
of late type
36- 41 F6.4 --- ProbEarly Probability of being a contact binary
of early type
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Note (1): There are five objects with more than one entry in the table:
KIC 3832716, KIC 7289157, KIC 9786821, KIC 10460629, KIC 11601584.
The reason is that for these objects, the Kepler Eclipsing Binary
Catalog registers multiple periods and the entries in our table
correspond to the different period estimates. The table is organized in
such a way that objects with identical KICs are ordered by increasing
period.
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Acknowledgements:
Milan Pesta, milan.pesta(at)utf.mff.cuni.cz
(End) Patricia Vannier [CDS] 08-Feb-2023