J/AJ/155/206 Search for rings around Kepler planet candidates (Aizawa+, 2018)
Systematic search for rings around Kepler planet candidates: constraints
on ring size and occurrence rate.
Aizawa M., Masuda K., Kawahara H., Suto Y.
<Astron. J., 155, 206-206 (2018)>
=2018AJ....155..206A 2018AJ....155..206A (SIMBAD/NED BibCode)
ADC_Keywords: Exoplanets ; Models ; Stars, diameters ;
Stars, double and multiple
Keywords: methods: data analysis - planets and satellites: detection -
planets and satellites: rings - techniques: photometric
Abstract:
We perform a systematic search for rings around 168 Kepler planet
candidates with sufficient signal-to-noise ratios that are selected
from all of the short-cadence data. We fit ringed and ringless models
to their light curves and compare the fitting results to search for
the signatures of planetary rings. First, we identify 29 tentative
systems, for which the ringed models exhibit statistically significant
improvement over the ringless models. The light curves of those systems
are individually examined, but we are not able to identify any candidate
that indicates evidence for rings. In turn, we find several mechanisms
of false positives that would produce ringlike signals, and the null
detection enables us to place upper limits on the size of the rings.
Furthermore, assuming the tidal alignment between axes of the planetary
rings and orbits, we conclude that the occurrence rate of rings larger
than twice the planetary radius is less than 15%. Even though the majority
of our targets are short-period planets, our null detection provides
statistical and quantitative constraints on largely uncertain theoretical
models of the origin, formation, and evolution of planetary rings.
Description:
In the present paper, we focus on the Kepler short-cadence (1 minute)
data alone. The long-cadence (29.4 minutes) data are not suitable for
searching for signatures of rings, which are identifiable only for short
timescales around the egress and ingress of the transit. We first retrieve
parameters from the Q1-Q17 Data Release 25 catalog of all Kepler objects
of interest (KOIs; Thompson et al. 2017, J/ApJS/235/38) and calculate
the S/Ns of those KOI planets that have short-cadence data. We exclude
the systems whose dispositions are "FALSE POSITIVE" in the catalog.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 115 14 Parameters and statistics of 14 systems with
p<0.003
table2.dat 115 15 Parameters and statistics of 15 systems with
0.003<p<0.05
table3.dat 115 139 Parameters and statistics of 139 systems with
p>0.05
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See also:
J/ApJ/812/46 : Transit metric for Q1-Q17 Kepler cand. (Thompson+, 2015)
J/ApJS/217/18 : Potential transit signals in Kepler Q1-Q17 (Seader+, 2015)
J/AJ/152/158 : Final Kepler transiting planet search DR25 (Twicken+, 2016)
J/ApJ/822/86 : False positive proba. for Q1-Q17 DR24 KOIs (Morton+, 2016)
J/ApJS/229/30 : Revised properties of Q1-17 Kepler targets (Mathur+, 2017)
J/ApJS/235/38 : Kepler planetary cand. VIII. DR25 reliability (Thompson+, 2018)
Byte-by-byte Description of file: table1.dat table2.dat table3.dat
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Bytes Format Units Label Explanations
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1- 7 F7.2 --- KOI [1.01/6969.01] Kepler Object of Interest
number (KOI -NNNN.NN in Simbad)
9- 13 A5 --- Kepler Kepler planet name (Kepler -NNNNAa in Simbad)
15- 20 F6.2 d Porb [0.53/328.24] Planetary orbital period (1)
22- 29 E8.3 Gyr tdamp [9e-10/79.4] Damping timescale
31 A1 --- l_Rout/RpA [<] Upper limit flag on Rout/RpA
32- 35 F4.2 --- Rout/RpA [1.02/9.7]? Ratio of the outer radius of the
possible ring and the planetary radius,
assuming the tidally aligned ring
configuration (Rout/Rp)upp,Aligned
37 A1 --- l_Rout/RpS [<] Upper limit flag on Rout/RpS
38- 41 F4.2 --- Rout/RpS [1.01/2.22]? Ratio of the outer radius of the
possible ring and the planetary radius,
assuming the Saturn's ring configuration
(Rout/Rp)upp,Saturn (not in Table 1)
43 A1 --- l_Rout/R* [<] Upper limit flag on Rout/R*
44- 48 F5.3 --- Rout/R* [0.021/0.463]? Ratio of the outer radius of
the ring and the stellar radius
(Rout/R*)upp (not in Table 1)
50- 57 F8.6 --- Rp/R* [0.0157/0.3] Planet-to-star radius ratio
(Rp/R*)ringless (2)
59- 63 E5.1 --- e_Rp/R* [4e-06/40] Uncertainty in Rp/R*
65 A1 --- l_p [<] Upper limit flag on p
66- 73 E8.3 --- p [1e-10/1] p-value (3)
75- 81 F7.2 --- chi2rgless [46.09/8830.73] Minimum value of χ2 for
the ringless model χ2ringless,min
83- 89 F7.2 --- chi2rg [31.21/5904.78] Minimum value of χ2 for
the ringed model χ2ring,min
91- 93 I3 --- Nbin [40/500] Number of in-transit bins of the
phase-folded light curve (typically 500)
95-101 F7.2 --- S/N [102.75/9353.67] Signal-to-noise ratio
103-115 A13 --- Com Comment (4)
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Note (1): Values from Kepler Object of Interest (KOI) Catalog Q1-Q17 DR 25
(https://exoplanetarchive.ipac.caltech.edu/).
Note (2): The values are obtained from the ringless model and the stellar radii
are taken from the Kepler catalog.
Note (3): According to the F-test, the measure of the null hypothesis that our
ringed model does not improve the fit relative to the ringless model is given
by the p-value (see Equation 5).
Note (4): Comment as follows:
FP = Possible false positive (https://exofop.ipac.caltech.edu/cfop.php);
GD = Gravity darkening (Appendix B.1);
Evap = Evaporating planet (Appendix B.2);
Spot = Spot crossing (Appendix B.3);
Bad fold = Incorrect data folding (Appendix B.4);
Small = Nonsignificant signal (Appendix B.5);
Others = Appendix B.6.
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History:
From electronic version of the journal
(End) Tiphaine Pouvreau [CDS] 07-Dec-2018