J/AJ/152/105 Kepler-80 transit timing observations (MacDonald+, 2016)
A dynamical analysis of the Kepler-80 system of five transiting planets.
MacDonald M.G., Ragozzine D., Fabrycky D.C., Ford E.B., Holman M.J.,
Isaacson H.T., Lissauer J.J., Lopez E.D., Mazeh T., Rogers L., Rowe J.F.,
Steffen J.H., Torres G.
<Astron. J., 152, 105-105 (2016)>
=2016AJ....152..105M 2016AJ....152..105M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Planets ; Photometry ; Spectroscopy ;
Stars, masses ; Stars, diameters
Keywords: methods: statistical - planetary systems -
planets and satellites: dynamical evolution and stability -
stars: individual: Kepler-80
Abstract:
Kepler has discovered hundreds of systems with multiple transiting
exoplanets which hold tremendous potential both individually and
collectively for understanding the formation and evolution of
planetary systems. Many of these systems consist of multiple small
planets with periods less than ∼50 days known as Systems with Tightly
spaced Inner Planets, or STIPs. One especially intriguing STIP,
Kepler-80 (KOI-500), contains five transiting planets: f, d, e, b, and
c with periods of 1.0, 3.1, 4.6, 7.1, and 9.5 days, respectively. We
provide measurements of transit times and a transit timing variation
(TTV) dynamical analysis. We find that TTVs cannot reliably detect
eccentricities for this system, though mass estimates are not
affected. Restricting the eccentricity to a reasonable range, we infer
masses for the outer four planets (d, e, b, and c) to be
6.75-0.51+0.69, 4.13-0.95+0.81, 6.93-0.70+1.05, and
6.74-0.86+1.23 Earth masses, respectively. The similar masses but
different radii are consistent with terrestrial compositions for d and
e and ∼2% H/He envelopes for b and c. We confirm that the outer four
planets are in a rare dynamical configuration with four interconnected
three-body resonances that are librating with few degree amplitudes.
We present a formation model that can reproduce the observed
configuration by starting with a multi-resonant chain and introducing
dissipation. Overall, the information-rich Kepler-80 planets provide
an important perspective into exoplanetary systems.
Description:
Kepler-80 was observed photometrically by the Kepler Space Telescope.
We had access to several sets of Transit Timing (TT) measurements,
including the publicly available data from Rowe & Thompson
(arXiv:1504.00707) and Mazeh et al. 2013 (Cat. J/ApJS/208/16). We also
had the updated long-cadence TT estimates from the Mazeh group
(Holczer et al. 2016, Cat. J/ApJS/225/9) and short-cadence TT data
from both co-authors JR and DF. These were all measured using similar
methods (see Mazeh et al. 2013, Cat. J/ApJS/208/16) and had no major
differences.
Spectra were taken of Kepler-80 by Keck and McDonald Observatories,
and these spectra and preliminary interpretations are available on the
Kepler Community Follow-up Observing Program (CFOP) website
(https://cfop.ipac.caltech.edu). We acquired an 1800s high-resolution
spectrum with the Keck I telescope and the High Resolution Echelle
Spectrometer (HIRES) on 2011 July 20. The standard California Planet
Search setup and data reduction of HIRES was used, resulting in a S/N
of 35 at 5500Å. The C2 decker, with dimensions of 0.87''*14'', was
used to allow a resolution of ∼60000 and sky subtraction.
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
----------------------------------------------------------
19 44 27.02 +39 58 43.6 Kepler-80 = KIC 4852528
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
planets.dat 17 4 Transiting planets of the Kepler-80 system
table1.dat 55 709 *Short-cadence transit time data
table3.dat 109 40000 Circular error propagation analysis
table4.dat 109 40000 Eccentric error propagation analysis
table7.dat 58 4687 *Transit time predictions
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Note on table1.dat: Short-cadence data used for the Transit Timing Variation
(TTV) fitting, reduced by author DF.
Note on table7.dat: Predictions of future transit times from our integrations
through 2025. These predictions were made using our eccentric bootstrapping
models.
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See also:
J/AJ/152/18 : Robo-AO Kepler planetary candidate survey. II. (Baranec+, 2016)
J/ApJ/822/86 : Q1-Q17 DR24 KOIs false positive probabilities (Morton+, 2016)
J/ApJ/821/47 : KOI transit probabilities of planets syst. (Brakensiek+, 2016)
J/ApJS/225/9 : Kepler TTVs. IX. Full long-cadence data set (Holczer+, 2016)
J/ApJ/790/146 : Planets in Kepler's multi-transiting systems (Fabrycky+, 2014)
J/ApJ/784/45 : Kepler's multiple planet candidates. III. (Rowe+, 2014)
J/ApJ/774/L12 : Kepler multiplanet systems analysis (Q1-Q8) (Steffen+, 2013)
J/ApJS/208/16 : Kepler transit timing observations. VIII. (Mazeh+, 2013)
J/ApJ/750/L37 : Stellar parameters of low-mass KOIs (Muirhead+, 2012)
J/ApJS/197/8 : Kepler's multiple transiting planets (Lissauer+, 2011)
J/ApJ/736/19 : Kepler planetary candidates. II. (Borucki+, 2011)
Byte-by-byte Description of file: planets.dat
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Bytes Format Units Label Explanations
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1- 6 F6.2 --- KOI Kepler Object of Interest (NNN.NN, decimal
places refer to the planet)
8- 17 A10 --- Kepler Kepler name for each planet
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 F6.2 --- KOI [500.01/500.04] Kepler Object of Interest
(NNN.NN, decimal places refer to the planet)
8- 17 A10 --- Kepler Kepler name for each planet (b, c, d, or e)
19- 22 I4 --- Transit [-236/237] Transit number assuming best-fit
period (transit 0 indicates the first transit
after the epoch of 793)
24- 34 F11.6 d TT [67/1524] Transit time (BJD-2454900)
36- 45 F10.7 d TTV [-0.05/0.066] Transit Time Variation
47- 55 F9.7 d e_TTV [0/0.019] Uncertainty in TTV
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Byte-by-byte Description of file: table[34].dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- Draw [1/10000] Random draw number (1)
7- 16 A10 --- Kepler Kepler name for each planet
18- 23 F6.4 Rsun Rstar [0.574/0.765] Stellar radius (R*) (2)
25- 30 F6.4 Msun Mstar [0.6/0.86] Stellar mass (M*) (2)
32- 37 F6.4 Rgeo Rp [1.2/3.3] Planet radius (Rp) (3)
39- 45 F7.4 Mgeo Mp [2/11.4] Planet mass (Mp) (3)
47- 54 F8.5 g/cm3 rhop [0.5/13] Planet density (ρp) (3)
56- 63 F8.6 AU a [0.03/0.09] Semi-major axis (a) (3)
65- 71 F7.4 deg i [85.4/90] Sky-plane inclination (i) (3)
73- 81 F9.7 --- e [0/0.022] Orbital eccentricity (e) (3)
83- 89 F7.4 deg w [0/92.2] Argument of periapsis (ω) (3)
91- 99 F9.7 d Per [3/9.6] Orbital period (P) (3)
101-109 F9.5 d T0 [758/797] Epoch t0 (BJD-2454900) (3)
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Note (1): In order to combine different sources of uncertainty, we employ a
Monte Carlo like error propagation analysis as discussed in the main text.
We performed a total of 10000 random draws for each planet and each row
represents one draw, indicated by the draw number.
Note (2): From a normal distribution based on our assumed stellar parameters
(Table2).
Note (3):
The mass ratio, period (P), and epoch (t0), eccentricity (e) and
argument of periapsis (ω) are drawn independently from the best-fits
of 30 circular bootstrapping runs. Finally, a third independent draw (with
replacement) is taken from the Markov Chain Monte Carlo (MCMC) posteriors
of Rowe et al. 2014 (Cat. J/ApJ/784/45) to determine the distribution of
planet-star radius ratio and impact parameter. The combination of these
properties allows us to derive the planet's mass (Mp), planet's radius
(Rp), density (ρp) from Equation (2):
ρp=ρ*(Mp/M*)(Rp/R*)3,
semimajor axis (a, from Kepler's third law), and sky-plane inclination (i).
Note that in Table4, the values of eccentricity (e) and argument of
periapse (ω) are probably inaccurate based on the discussion in
Section 4.4.
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- Kepler Kepler name for each planet
12- 15 I4 --- Transit [-242/1694] Transit number (1)
17- 33 F17.9 d TT Transit time (BJD)
35- 46 F12.10 d E_TT Upper uncertainty on TT (σ+) (2)
48- 58 F11.9 d e_TT Lower uncertainty on TT (σ-) (2)
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Note (1): Transit 0 indicates the first transit after the epoch of BJD 2454693.
Note (2): The upper bound is taken to include the 84th percentile; the lower
bound uncertainty is taken to include the 16th percentile. Uncertainties
are given in units of days and are about 10 minutes in the near term (2016)
and grow to about 30 minutes by 2025.
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History:
From electronic version of the journal
(End) Prepared by [AAS]; Sylvain Guehenneux [CDS] 19-May-2017