J/AJ/154/64 Transit times of Kepler-448b and Kepler-693b (Masuda, 2017)
Eccentric companions to Kepler-448b and Kepler-693b: clues to the formation of
warm Jupiters.
Masuda K.
<Astron. J., 154, 64-64 (2017)>
=2017AJ....154...64M 2017AJ....154...64M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Planets ; Stars, diameters
Keywords: planets and satellites: individual KOI-12, Kepler-448, KIC 5812701,
KOI-824, Kepler-693, KIC 5164255
Abstract:
I report the discovery of non-transiting close companions to two
transiting warm Jupiters (WJs), Kepler-448/KOI-12b (orbital period
P=17.9days, radius Rp=1.23-0.05+0.06RJup) and
Kepler-693/KOI-824b (P=15.4days, Rp=0.91±0.05RJup), via
dynamical modeling of their transit timing and duration variations
(TTVs and TDVs). The companions have masses of 22-5+7MJup
(Kepler-448c) and 150-40+60MJup (Kepler-693c), and both are on
eccentric orbits (e=0.65-0.09+0.13 for Kepler-448c and
e=0.47-0.06+0.11 for Kepler-693c) with periastron distances of
1.5au. Moderate eccentricities are detected for the inner orbits as
well (e=0.34-0.07+0.08 for Kepler-448b and e=0.2-0.1+0.2 for
Kepler-693b). In the Kepler-693 system, a large mutual inclination
between the inner and outer orbits (53-9+7deg or 134-10+11deg)
is also revealed by the TDVs. This is likely to induce a secular
oscillation in the eccentricity of the inner WJ that brings its
periastron close enough to the host star for tidal star-planet
interactions to be significant. In the Kepler-448 system, the mutual
inclination is weakly constrained, and such an eccentricity
oscillation is possible for a fraction of the solutions. Thus these
WJs may be undergoing tidal migration to become hot Jupiters (HJs),
although the migration via this process from beyond the snow line is
disfavored by the close-in and massive nature of the companions. This
may indicate that WJs can be formed in situ and could even evolve into
HJs via high-eccentricity migration inside the snow line.
Description:
I analyzed Transit Timing Variations (TTVs) of 23 confirmed, singly
transiting warm Jupiters (WJs; Section 2.1) with an orbital period of
7days<P<100days and a radius of Rp>8R⊕ in the DR24 of the
KOI catalog (Coughlin et al. 2016, Cat. J/ApJS/224/12). Systems with
multiple KOIs are all excluded, even though they consist of only one
confirmed planet and false positives. I found clearly non-sinusoidal
TTVs for Kepler-448/KOI-12b, Kepler-693/KOI-824b, and
Kepler-419/KOI-1474b. The result is consistent with the TTV search by
Holczer et al. 2016 (Cat. J/ApJS/225/9), who reported significant
long-term TTVs for the same three KOIs in our sample.
Of these planets, the TTVs of Kepler-419b have previously been
analyzed by Dawson et al. (2014ApJ...791...89D 2014ApJ...791...89D). Therefore, I focus on
Kepler-448b and Kepler-693b.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
planets.dat 21 2 Analyzed planets
table1.dat 47 71 Transit times, durations, and radius ratios of
Kepler-448b
table2.dat 47 50 Transit times, durations, and radius ratios of
Kepler-693b
--------------------------------------------------------------------------------
See also:
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
J/ApJS/225/9 : Kepler TTVs. IX. Full long-cadence data set (Holczer+, 2016)
J/ApJS/224/12 : Kepler planetary candidates. VII. 48-month (Coughlin+, 2016)
Byte-by-byte Description of file: planets.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- Name Planet name
13- 21 F9.6 d Per Period (from Table 3 or 4 in the paper)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table[12].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Num [-1/90] Transit number
4- 12 F9.4 d TT [128.742/1575.02] Transit time in Barycentric
Julian Date (BJDTDB-2454833)
14- 19 F6.4 d e_TT [0.0001/0.003] Uncertainty in TT (1)
21- 26 F6.4 d Dur [0.091/0.282] Transit duration
28- 33 F6.4 d e_Dur [0.0002/0.009] Uncertainty in Dur (1)
35- 40 F6.4 --- Rp/Rs [0.0882/0.137] Planet-to-star radius ratio
42- 47 F6.4 --- e_Rp/Rs [0.0003/0.008] Uncertainty in ratio (1)
--------------------------------------------------------------------------------
Note (1): For Kepler-448b, quoted uncertainties are the standard errors derived
from the covariance matrix scaled by (χ2/d.o.f.)0.5 of the fit.
For Kepler-693b, quoted uncertainties are the standard errors derived from
the covariance matrix scaled by (χ2/d.o.f.)0.5 of the fit or are
based on the combination of the Long-Cadence (LC) and Short-Cadence (SC)
data (see Section 2.2).
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS]; Sylvain Guehenneux [CDS] 08-Nov-2017