J/A+A/567/A14 RV and g'z' transits of KOI-1089b/Kepler-418b (Tingley+, 2014)
Confirmation of an exoplanet using the transit color signature:
Kepler-418b, a blended giant planet in a multiplanet system.
Tingley B., Parviainen H., Gandolfi D., Deeg H.J., Palle E.,
Montanes Rodriguez P., Murgas F., Alonso R., Bruntt H., Fridlund M.
<Astron. Astrophys. 567, A14 (2014)>
=2014A&A...567A..14T 2014A&A...567A..14T
ADC_Keywords: Stars, double and multiple ; Planets ; Photometry, SDSS ;
Radial velocities
Keywords: techniques: photometric - planetary systems -
star: individual: KOI 1089 - star: individual: KIC 3247268
Abstract:
We announce confirmation of Kepler-418b, one of two proposed planets
in this system. This is the first confirmation of an exoplanet based
primarily on the transit color signature technique.
We used the Kepler public data archive combined with multicolor
photometry from the Gran Telescopio de Canarias and radial velocity
follow-up using FIES at the Nordic Optical Telescope for confirmation.
We report a confident detection of a transit color signature that can
only be explained by a compact occulting body, entirely ruling out a
contaminating eclipsing binary, a hierarchical triple, or a grazing
eclipsing binary. Those findings are corroborated by our radial
velocity measurements, which put an upper limit of ∼1Mjup on the
mass of Kepler-418b. We also report that the host star is
significantly blended, confirming the ∼10% light contamination
suspected from the crowding metric in the Kepler light curve measured
by the Kepler team. We report detection of an unresolved light source
that contributes an additional ∼40% to the target star, which would
not have been detected without multicolor photometric analysis. The
resulting planet-star radius ratio is 0.110±0.0025, more than 25%
more than the 0.087 measured by Kepler, leading to a radius of
1.20±0.16Rjup instead of the 0.94Rjup measured by the Kepler
team.
This is the first confirmation of an exoplanet candidate based
primarily on the transit color signature, demonstrating that this
technique is viable from ground for giant planets. It is particularly
useful for planets with long periods such as Kepler-418b, which tend
to have long transit durations. While this technique is limited to
candidates with deep transits from the ground, it may be possible to
confirm earth-like exoplanet candidates with a few hours of observing
time with an instrument like the James Webb Space Telescope.
Additionally, multicolor photometric analysis of transits can reveal
unknown stellar neighbors and binary companions that do not affect the
classification of the transiting object but can have a very
significant effect on the perceived planetary radius.
Description:
g' and z' band photometry of KOI-1089b/Kepler-418b taken with the GTC
on the night of 14 Aug 2011. Radial velocities of the same taken with
NOT.
Objects:
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RA (2000) DE Designation(s)
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19 37 44.04 +38 21 19.6 Kepler-418 = KOI-1089
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
z_gtc.dat 22 930 GTC z' photometry of KOI-1089b/Kepler-418b
g_gtc.dat 22 930 GTC g' photometry of KOI-1089b/Kepler-418b
rv_not.dat 27 7 NOT radial velocities of KOI-1089b/Kepler-418b
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See also:
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
Byte-by-byte Description of file: z_gtc.dat g_gtc.dat
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Bytes Format Units Label Explanations
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1- 12 F12.6 --- MJD Modifed Julian Date of observation
14- 20 F7.4 mag dmag Differential g' or z' magnitude
22 A1 --- Band [gz] Observed band (g' or z')
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Byte-by-byte Description of file: rv_not.dat
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Bytes Format Units Label Explanations
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1- 10 F10.5 d HJD Heliocentric Julian Date (HJD-2450000)
12- 18 F7.3 km/s RV Observered Radial Velocity
20- 24 F5.3 km/s e_RV Error on observed Radial Velocity
26- 27 I2 pix-1 S/N Signal-to-noise per pixel at 5500Å
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Acknowledgements:
Brandon Tingley, tingley(at)phys.au.dk
(End) Brandon Tingley [AU, Denmark], Patricia Vannier [CDS] 21-May-2014