J/AJ/165/48 Transit times for Kepler-289 b, c and d (Greklek-McKeon+, 2023)
Constraining the Densities of the Three Kepler-289 Planets with Transit Timing
Variations.
Greklek-McKeon M., Knutson H.A., Vissapragada S., Jontof-Hutter D.,
Chachan Y., Thorngren D., Vasisht G.
<Astron. J., 165, 48 (2023)>
=2023AJ....165...48G 2023AJ....165...48G
ADC_Keywords: Exoplanets; Photometry, infrared
Keywords: Infrared photometry ; Transit timing variation method ; Transits
Abstract:
Kepler-289 is a three-planet system containing two sub-Neptunes and
one cool giant planet orbiting a young, Sun-like star. All three
planets exhibit transit timing variations (TTVs), with both adjacent
planet pairs having orbital periods close to the 2:1 orbital
resonance. We observe two transits of Kepler-289c with the Wide-field
InfraRed Camera on the 200" Hale Telescope at Palomar Observatory,
using diffuser-assisted photometry to achieve space-like photometric
precision from the ground. These new transit observations extend the
original four-year Kepler TTV baseline by an additional 7.5yr. We
rereduce the archival Kepler data with an improved stellar activity
correction and carry out a joint fit with the Palomar data to
constrain the transit shapes and derive updated transit times. We then
model the TTVs to determine the masses of the three planets and
constrain their densities and bulk compositions. Our new analysis
improves on previous mass and density constraints by a factor of two
or more for all three planets, with the innermost planet showing the
largest improvement. Our updated atmospheric mass fractions for the
inner two planets indicate that they have hydrogen-rich envelopes,
consistent with their location on the upper side of the radius valley.
We also constrain the heavy element composition of the outer Saturn
mass planet, Kepler-289c, for the first time, finding that it contains
30.5±6.9M⊕ of metals. We use dust evolution models to show
that Kepler-289c must have formed beyond 1au, and likely beyond 3au,
and then migrated inward.
Description:
The Kepler-289 system was observed continuously during Kepler Quarters
116, with only long-cadence data available for the first eleven
quarters, and short-cadence data in the remaining five. We obtained
the Pre-search Data Conditioning Simple Aperture Photometry (PDCSAP)
flux from the Kepler-289 postage stamp in Quarters 116 from the
Mikulski Archive for Space Telescopes (MAST).
Kepler-289c's 126day orbital period makes it a challenging target to
observe from the ground, as the transit has a total duration of ∼8hr
and there are typically no opportunities to observe full transits of
this planet at Palomar. We obtained two partial transits of
Kepler-289c in J band using the WIRC instrument at the prime focus of
the 200" Hale Telescope at Palomar Observatory.
Objects:
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RA (2000) DE Designation(s)
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19 49 51.67 +42 52 58.2 Kepler-289 = 2MASS J19495168+4252582
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 49 466 Observed transit epochs and mid-times for the three
Kepler-289 planets
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See also:
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/795/167 : Transits of PH3 b, c, & d through January 2019 (Schmitt+, 2014)
J/ApJS/225/9 : Kepler TTVs IX. The full long-cadence data set (Holczer+, 2016)
J/ApJ/831/64 : Mass-metallicity relation for giant planets (Thorngren+, 2016)
J/AJ/154/5 : Transit timing variations of 145 Kepler planets (Hadden+, 2017)
J/AJ/157/52 : Radial velocity observations super-Earth systems (Bryan+, 2019)
J/ApJ/874/L31 : Giant planet bulk & atmosphere metallicities (Thorngren+, 2019)
J/AJ/161/246 : Tansit time variations for 12 exoplanets (Jontof-Hutter+, 2021)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- ID Planet identifier
13- 15 I3 --- Num [0/465] Transit epoch number
17- 25 F9.4 d ObsJD [964/4720]? Observed Julian Date of mid-time;
JD-2454000
27- 32 F6.4 d e_ObsJD [0.0004/0.03]? 1σ uncertainty in ObsJD
34- 42 F9.4 d PredJD [965/9891] Predicted Julian Date of mid-time;
JD-2454000
44- 49 F6.4 d e_PredJD [0.0002/2] 1σ uncertainty in Pred-JD
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 26-May-2023