J/AJ/157/192 Radial velocities and transit times for KOI 4 (Chontos+, 2019)
The curious case of KOI 4: confirming Kepler's first exoplanet detection.
Chontos A., Huber D., Latham D.W., Bieryla A., Van Eylen V., Bedding T.R.,
Berger T., Buchhave L.A., Campante T.L., Chaplin W.J., Colman I.L.,
Coughlin J.L., Davies G., Hirano T., Howard A.W., Isaacson H.
<Astron. J., 157, 192 (2019)>
=2019AJ....157..192C 2019AJ....157..192C (SIMBAD/NED BibCode)
ADC_Keywords: Binaries, eclipsing ; Radial velocities ; Exoplanets
Keywords: asteroseismology - planets and satellites: individual (KOI 4.01) -
stars: individual (Kepler-1658) -
techniques: photometric, radial velocities, spectroscopic
Abstract:
The discovery of thousands of planetary systems by Kepler has demonstrated
that planets are ubiquitous. However, a major challenge has been the
confirmation of Kepler planet candidates, many of which still await
confirmation. One of the most enigmatic examples is KOI 4.01, Kepler's
first discovered planet candidate detection (as KOI 1.01, 2.01, and 3.01
were known prior to launch). Here we present the confirmation and
characterization of KOI 4.01 (now Kepler-1658), using a combination of
asteroseismology and radial velocities. Kepler-1658 is a massive, evolved
subgiant (M*=1.45±0.06 M☉, R*=2.89±0.12 R☉) hosting
a massive (Mp=5.88±0.47 MJ, Rp=1.07±0.05 RJ) hot Jupiter that
orbits every 3.85 days. Kepler-1658 joins a small population of evolved
hosts with short-period (~<100 days) planets and is now the closest known
planet in terms of orbital period to an evolved star. Because of its
uniqueness and short orbital period, Kepler-1658 is a new benchmark system
for testing tidal dissipation and hot Jupiter formation theories. Using
all four years of the Kepler data, we constrain the orbital decay rate
to be P=←0.42 s/yr, corresponding to a strong observational limit of
Q'*≥4.826x103 for the tidal quality factor in evolved stars. With
an effective temperature of Teff∼6200 K, Kepler-1658 sits close to
the spin-orbit misalignment boundary at ∼6250 K, making it a prime target
for follow-up observations to better constrain its obliquity and to
provide insight into theories for hot Jupiter formation and migration.
Description:
Following the asteroseismic reclassification of the host star, we
initiated an intensive radial velocity (RV) follow-up program using
the Tillinghast Reflector Echelle Spectrograph (TRES), a fiber-fed
echelle spectrograph spanning the spectral range of 3900-9100 Å
with a resolving power of R∼44000. We obtained 23 spectra with TRES
between UT 2009 November 8 and 2017 September 13 using the medium 2.3"
fiber. The spectra were reduced and extracted as outlined in Buchhave
et al. (2010, J/ApJ/720/1118). The average exposure time of ∼1800 s,
corresponding to a mean signal-to-noise ratio (S/N) per resolution
element of ∼53 at the peak of the continuum near the Mg b triplet at
519 nm. We used the strongest S/N spectrum as a template to derive
relative RVs by cross-correlating the remaining spectra order-by-order
against the template, which is given a relative velocity of 0 km/s, by
definition.
Objects:
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RA (ICRS) DE Designation(s)
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19 37 25.57 +38 56 50.5 KOI 4 = Kepler-1658
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 43 23 TRES radial velocity observations
table5.dat 43 210 Individual transit times
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See also:
J/ApJ/720/1118 : i-band photometry of HAT-P-16 (Buchhave+, 2010)
J/other/Nat/486.375 : Stellar parameters of KOI stars (Buchhave+, 2012)
J/ApJS/224/12 : Kepler planetary candidates. VII. 48-month
(Coughlin+, 2016)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 14 F14.6 d BJD Barycentric Julian Date of observation (TDB)
16- 23 F8.2 m/s RV [-1611.87/0] Radial velocity
25- 30 F6.2 m/s e_RV [103.28/261.2] Uncertainty in RV
32- 37 F6.1 m/s BS [-274.6/244.2] Line bisector span
39- 43 F5.1 m/s e_BS [40.9/205.7] Uncertainty in BS
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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- 16 F16.8 d Epoch Barycentric Julian Date (TDB)
18- 29 F12.10 d p84 [0.0008533164/0.0039025636] 84% confidence interval
31- 43 F13.10 d p16 [-0.0038223366/-0.000809545] 16% confidence interval
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 05-Aug-2019