Kepler-62f: Kepler's First Small Planet in the Habitable Zone, but Is It Real?


Phase-folded light curve for Kepler-62f for Quarters 0-17. Data from all 4 transits are averaged to produce the above light curve. One sigma errors are shown with vertical bars. The continuous curve shows the model fit from Borucki et al. 2013.

Kepler-62f is the first exoplanet small enough to plausibly have a rocky composition orbiting within the habitable zone (HZ) discovered by the Kepler Mission.

The planet is 1.4 times the size of the Earth and has an orbital period of 267 days. At the time of its discovery, it had the longest period of any small planet in the habitable zone of a multi-planet system. Because of its long period, only four transits were observed during Kepler's interval of observations. It was initially missed by the Kepler pipeline, but the first three transits were identified by an independent search by Eric Agol, and it was identified as a planet candidate in subsequent Kepler catalogs. However in the latest catalog of exoplanets (Thompson et al., 2018), it is labeled as a false positive. Recent exoplanet catalogues have evolved from subjective classification to automatic classifications of planet candidates by algorithms (such as `Robovetter').

While exceptionally useful for producing a uniform catalogue, these algorithms sometimes misclassify planet candidates as a false positive, as is the case of Kepler-62f. In particularly valuable cases, i.e., when a small planet has been found orbiting in the habitable zone (HZ), it is important to conduct comprehensive analyses of the data and classification protocols to provide the best estimate of the true status of the detection. In this paper we conduct such analyses and show that Kepler-62f is a true planet and not a false positive. The table of stellar and planet properties has been updated based on GAIA results.

William Borucki, Susan E. Thompson, Eric Agol, Christina Hedges
(Submitted on 14 May 2019)
Comments: Published in New Astronomy Reviews special issue on key Kepler discoveries
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:1905.05719 [astro-ph.EP] (or arXiv:1905.05719v1 [astro-ph.EP] for this version)
Submission history
From: Eric Agol
[v1] Tue, 14 May 2019 16:55:02 UTC (650 KB)
https://arxiv.org/abs/1905.05719
Astrobiology

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