J/ApJS/197/2 Transit timing observations from Kepler. I. (Ford+, 2011)
Transit timing observations from Kepler.
I. Statistical analysis of the first four months.
Ford E.B., Rowe J.F., Fabrycky D.C., Carter J.A., Holman M.J.,
Lissauer J.J., Ragozzine D., Steffen J.H., Batalha N.M., Borucki W.J.,
Bryson S., Caldwell D.A., Dunham E.W., Gautier T.N., Jenkins J.M.,
Koch D.G., Li J., Lucas P., Marcy G.W., McCauliff S., Mullally F.R.,
Quintana E., Still M., Tenenbaum P., Thompson S.E., Twicken J.D.
<Astrophys. J. Suppl. Ser., 197, 2 (2011)>
=2011ApJS..197....2F 2011ApJS..197....2F
ADC_Keywords: Stars, double and multiple ; Planets
Keywords: methods: statistical - planetary systems - planets and satellites:
detection - planets and satellites: dynamical evolution and
stability - techniques: miscellaneous
Abstract:
The architectures of multiple planet systems can provide valuable
constraints on models of planet formation, including orbital
migration, and excitation of orbital eccentricities and inclinations.
NASA's Kepler mission has identified 1235 transiting planet
candidates. The method of transit timing variations (TTVs) has already
confirmed seven planets in two planetary systems. We perform a transit
timing analysis of the Kepler planet candidates. We find that at least
∼11% of planet candidates currently suitable for TTV analysis show
evidence suggestive of TTVs, representing at least ∼65 TTV candidates.
In all cases, the time span of observations must increase for TTVs to
provide strong constraints on planet masses and/or orbits, as expected
based on N-body integrations of multiple transiting planet candidate
systems (assuming circular and coplanar orbits).
Description:
In this paper, we analyze putative transit timing variations (TTs) by
Kepler planet candidates that show at least three transits in Q0-2.
Kepler began collecting engineering data ("quarter" 0, Q0) for stars
brighter than Kepler magnitude (Kp) 13.6 on 2009 May 2, and science
data for over 150000 stars on 2009 May 13. The first "quarter" (Q1)
of Kepler data extends through 2009 June 15 and the second quarter
(Q2) runs from 2009 June 20 to September 16. On 2011 February 1, the
Kepler team released light curves during Q0, Q1, and Q2 for all planet
search targets via the Multi-Mission Archive at the Space Telescope
Science Institute (MAST; http://archive.stsci.edu/kepler/). The Kepler
team has performed an initial transiting planet search to identify
Kepler Objects of Interests (KOIs) that show transit-like events
during Q0-2 (Borucki et al. 2011, Cat. J/ApJ/736/19).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 50 21217 Transit times for Kepler transiting planet
candidates during Q0-2
table2.dat 42 1197 Linear transit ephemerides based on Q0-2
transit times
table3.dat 103 1050 Metrics for transit timing variations (TTs) of
Kepler planet candidates
table4.dat 135 14 Quadratic ephemerides for Kepler objects of
interest (KOI) based on transit times during Q2
table5.dat 103 149 Notes for Kepler planet candidates with putative
transit timing variations
table6.dat 66 401 Predicted transit time variation magnitude for
Kepler transiting planet candidates
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See also:
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
J/ApJ/736/19 : Kepler planetary candidates. II. (Borucki+, 2011)
J/ApJ/728/117 : Kepler planetary candidates. I. (Borucki+, 2011)
J/A+A/528/A63 : Velocitometry transit of KOI-428b (Santerne+, 2011)
J/A+A/529/A89 : Kepler satellite variability study (Debosscher+, 2011)
J/AJ/128/1761 : HATNET variability survey (Hartman+, 2004)
http://archive.stsci.edu/kepler : MAST Kepler home page
http://archive.stsci.edu/kepler/planet_candidates.html : Released
Kepler Planetary Candidates
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 7 F7.2 --- KOI Kepler Object Identifier number (NNNN.NN)
9- 11 I3 --- n Transit number
13- 22 F10.6 d t-2454900 Barycentric Julian Date of transit (1)
24- 36 F13.6 d TTvar Transit time variation
38- 50 F13.6 d e_TTvar Uncertainty in TTvar
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Note (1): Note that the TTs are measured relative to the EL5 ephemerides given
in Borucki et al. (2011, Cat. J/ApJ/736/19) and this is based on
transit times measured through Q5. In some cases, a long-term trend
manifests itself as all the reported values of TTs having the same sign.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 8 I8 --- KIC Identification from Kepler Input Catalog (1)
10- 16 F7.2 --- KOI Kepler Object Identifier number (NNNN.NN)
18- 27 F10.6 d Ep-2454900 Barycentric Julian Date (BJD-2454900)
29- 42 F14.8 d Period Period
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Note (1): as in Cat. V/133; added at CDS in January 2011, from
http://archive.stsci.edu/kepler/planet_candidates.html
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 7 F7.2 --- KOI Kepler Object Identifier number (NNNN.NN)
9- 13 F5.1 min sigTT Median transit time measurement uncertainty
15- 21 F7.1 min MAD-5 EL5,T2 Median Absolute Deviation (1)
23- 29 F7.1 min WRMS-5 EL5,T2 Weighted Root Mean Square deviation (1)
31- 38 F8.1 min MAX-5 EL5,T2 MAXimum absolute deviation (1)
40- 54 E15.9 --- pX2-5 EL5,T2 p-value for a χ2-like-test (2)
56- 61 F6.1 min MAD-2 EL2,T2 Median Absolute Deviation (3)
63- 67 F5.1 min WRMS-2 EL2,T2 Weighted Root Mean Square deviation (3)
69- 75 F7.1 min MAX-2 EL2,T2 MAXimum absolute deviation (3)
77- 91 E15.9 --- pX2-2 EL2,T2 p-value for a χ2-like-test (2)
93- 97 F5.1 --- DelP Absolute value of difference of best-fit
periods ΔP (4)
99-103 F5.1 --- DelE ? Absolute value of difference of best-fit
transit ΔE epochs (4)
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Note (1): Of transit times in Q0-2 from EL5T2 ephemeris based on transit
times measured during Q0-5, taken from Borucki et al.
(2011, Cat. J/ApJ/736/19).
Note (2): Assuming X'2 follows a χ2 distribution, as described
in Section 3.1.
Note (3): Of transit times in Q0-2 from EL2T2 ephemeris based on transit
times measured during Q0-2 only.
Note (4): For L2,T2 and L5,T2 ephemerides normalized by formal uncertainty.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 7 F7.2 --- KOI Kepler Object Identifier number (NNNN.NN)
9- 17 F9.5 d Epoch Epoch (Ep-2454900)
19- 29 F11.9 d e_Epoch Epoch uncertainty
31- 39 F9.6 d Per Period
41- 51 F11.9 d e_Per Period uncertainty
53- 64 E12.4 --- c Curvature (see equation (1))
66- 76 E11.3 --- e_c Curvature uncertainty
78- 88 E11.3 d MAD Median absolute deviation of TTs from
quadratic ephemeris
90-100 E11.3 d WRMS Weighted root mean square deviation of TTs
from quadratic ephemeris
102-112 F11.9 d MAX Maximum absolute deviation of TTs from quadratic
ephemeris
114-123 F10.8 --- pX2 p-value for a χ2-test based on χ'2
relative to quadratic ephemeris (1)
125-135 F11.9 --- pF p-value for an F-like test that compares linear
and quadratic ephemerides (2)
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Note (1): As described in Section 3.1.
Note (2): Assuming that F follows an F distribution, as described in section 3.1
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 7 F7.2 --- KOI Kepler Object Identifier number (NNNN.NN)
9- 18 F10.7 d Per Period
20- 23 F4.1 Rgeo Rp Putative planet radius in Earth radii (1)
25- 29 F5.1 --- S/N Typical S/N of an individual transit
31- 34 F4.1 h Tdur Transit duration (1)
36- 38 I3 --- nTT Number of transit times measured in Q0-2
40 I1 --- nP Number of transiting planet candidates for host
star
42 I1 --- TTV Transit time variation flag (2)
44-103 A60 --- Com Additional comments
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Note (1): From Borucki et al. (2011, Cat. J/ApJ/736/19).
Note (2): Flag as follows:
1 = Pattern to eye;
2 = Trend or periodicity;
3 = Excess scatter and no trend;
4 = Low S/N per transit and/or few transits;
5 = Note about difficulty measuring TTs;
6 = Excess scatter significant only after clipping.
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 7 F7.2 --- KOI Kepler Object Identifier number (NNNN.NN)
9- 17 F9.5 s RMS-Q2 ? Q2 RMS (1)
19- 27 F9.4 s M2M-Q2 ? Q2 min-to-max (1)
29- 37 F9.3 s RMS-3.5 The 3.5 year RMS (1)
39- 46 F8.2 s M2M-3.5 The 3.5 year min-to-max (1)
48- 56 F9.3 s RMS-7 The 7 year RMS (1)
58- 66 F9.2 s M2M-7 The 7 year min-to-max (1)
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Note (1): We report the magnitude (root mean square and min-to-max) of
transit timing variations expected based on n-body integrations using
estimated nominal masses and initially circular orbits (Lissauer et
al. 2011PhRvA..84b1602S 2011PhRvA..84b1602S). We assume that all members of multiple
planet candidate systems are true planets and orbit the same star.
Integrations extend for the duration of the first two quarters of
Kepler data, the nominal 3.5 year mission life time and 7.5 years,
representative of a hypothetical extended mission. Eccentric models
can dramatically affect both the predicted TTV magnitude and timescale.
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History:
* 01-Dec-2011: From electronic version of the journal
* 15-Jan-2012: Added KIC number in table2, from
http://archive.stsci.edu/kepler/planet_candidates.html
References:
Ford et al. Paper II. 2012ApJ...750..113F 2012ApJ...750..113F Cat. J/ApJ/750/113
Steffen et al. Paper III. 2012MNRAS.421.2342S 2012MNRAS.421.2342S Cat. J/MNRAS/421/2342
Fabrycky et al. Paper IV. 2012ApJ...750..114F 2012ApJ...750..114F Cat. J/ApJ/750/114
Ford et al. Paper V. 2012ApJ...756..185F 2012ApJ...756..185F
Steffen et al. Paper VI. 2012ApJ...756..186S 2012ApJ...756..186S
Steffen et al. Paper VII. 2013MNRAS.428.1077S 2013MNRAS.428.1077S
Mazeh et al. Paper VIII. 2013ApJS..208...16M 2013ApJS..208...16M Cat. J/ApJS/208/16
Holczer et al. Paper IX. 2016ApJS..225....9H 2016ApJS..225....9H Cat. J/ApJS/225/9
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 01-Dec-2011