MODELING KEPLER TRANSIT LIGHT CURVES AS FALSE POSITIVES: REJECTION OF BLEND SCENARIOS FOR KEPLER-9, AND VALIDATION OF KEPLER-9 d, A SUPER-EARTH-SIZE PLANET IN A MULTIPLE SYSTEM

By G. Torres, F. Fressin, N. Batalha, William J. Borucki, T. Brown, S. Bryson, Lars A. Buchhave, D. Charbonneau, D. Ciardi, E. Dunham and 20 more. 2010

196 citations recorded by the source corpus.

Light curves from the Kepler Mission contain valuable information on the nature of the phenomena producing the transit-like signals. To assist in exploring the possibility that they are due to an astrophysical false positive, we describe a procedure (BLENDER) to model the photometry in terms of a “blend” rather than a planet orbiting a star. A blend may consist of a background or foreground eclipsing binary (or star–planet pair) whose eclipses are attenuated by the light of the candidate and possibly other stars within the photometric aperture. We apply BLENDER to the case of Kepler-9 (KIC 3323887), a target harboring two previously confirmed Saturn-size planets (Kepler-9 b and Kepler-9 c) showing transit timing variations, and an additional shallower signal with a 1.59 day period suggesting the presence of a super-Earth-size planet. Using BLENDER together with constraints from other follow-up observations we are able to rule out all blends for the two deeper signals and provide independent validation of their planetary nature. For the shallower signal, we rule out a large fraction of the false positives that might mimic the transits. The false alarm rate for remaining blends depends in part (and inversely) on the unknown frequency of small-size planets. Based on several realistic estimates of this frequency, we conclude with very high confidence that this small signal is due to a super-Earth-size planet (Kepler-9 d) in a multiple system, rather than a false positive. The radius is determined to be 1.64+0.19−0.14 R⊕, and current spectroscopic observations are as yet insufficient to establish its mass.

Subfields: Astronomy and Astrophysics

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1. D. Charbonneau
2. Timothy Morton
3. Jon Fortney
4. J. Johnson
5. J. Winn
6. Andrew W. Howard
7. G. Marcy
8. Sara Seager

Citations in the corpus

• STELLAR AND PLANETARY PROPERTIES OF K2 CAMPAIGN 1 CANDIDATES AND VALIDATION OF 17 PLANETS, INCLUDING A PLANET RECEIVING EARTH-LIKE INSOLATION (2015, methodology): “Similar in spirit to other published methods of probabilistic validation, such as BLENDER (Torres et al. 2011) and PASTIS (Díaz et al. 2014), it has the advantage of being computationally less demanding and fully automated, and thus easily applied in batch to a large number of candidates.”
• THE KEPLER FOLLOW-UP OBSERVATION PROGRAM. I. A CATALOG OF COMPANIONS TO KEPLER STARS FROM HIGH-RESOLUTION IMAGING (2016, methodology): “Some of the AO data presented here (mostly from Palomar and Keck) have already been published in the liter- ature (Torres et al. 2011; Batalha et al. 2011; Fortney et al. 2011; Ballard et al. 2011, 2013; Borucki et al. 2012, 2013; Gautier et al. 2012; Adams et al. 2012; Marcy et al. 2014; Everett…”
• PASTIS: Bayesian extrasolar planet validation. I. General framework, models, and performance (2014, methodology): “In addition, the models involving a diluted EB should also be constructed using a period twice the nominal transit period, but these scenarios are generally easily discarded by the data (e.g. Torres et al. 2011).”
• Prevalence of Earth-size planets orbiting Sun-like stars (2013, background): “ But in this work, we extend our search in orbital period to P= 0.5–400 days. S5 Table S1. TERRA Grid Search Parameters P 1 P 2 Trial Transit Duration ( T) days days long cadence measurements 5.0 7.7 [3, 4, 5, 7, 9, 11] 7.7 12.0 [4, 5, 7, 9, 13] 12.0 18.6 [4, 5, 7, 9, 13, 15] 18.6 28.9 [5, 7, 9, 12,”
• SOPHIE velocimetry of Kepler transit candidates VII. A false-positive rate of 35% for Kepler close-in giant candidates (2012, background): “Another solution is to “validate” the candidate by excluding all false-positive scenarios with a significant confidence level (the so-called “BLENDER” technique, e.g. Torres et al. 2011; Fressin et al. 2011).”
• The California-Kepler Survey. I. High-resolution Spectroscopy of 1305 Stars Hosting Kepler Transiting Planets (2017, background): “…values into planet candidates (Jenkins et al. 2010; Gilliland et al. 2010; Stumpe et al. 2012; Smith et al. 2012, 2016; Batalha et al. 2010a,b; Torres et al. 2011; Bryson et al. 2013; Christiansen et al. 2012, 2013, 2015, 2016; Thompson et al. 2015; McCauliff et al. 2015; Tenenbaum et al.…”
• KEPLER'S FIRST ROCKY PLANET: KEPLER-10b (2011, methodology): “Translating this into a probability statement for the planet likelihood is difficult, as argued by Torres et al. (2010), because it requires knowledge of the rate of occurrence of super-Earth-size planets, a quantity that is not yet in hand.”
• THE KEPLER-10 PLANETARY SYSTEM REVISITED BY HARPS-N: A HOT ROCKY WORLD AND A SOLID NEPTUNE-MASS PLANET (2014, methodology): “With more Kepler data and simultaneous Spitzer Space Telescope photometry, Fressin et al. (2011) reanalyzed the Kepler-10 system and statistically validated the planetary nature of Kepler-10c with BLENDER (Torres et al. 2011).”