Targets of Note: Kepler-452 b

Affirming the validity of a Kepler planet involves two distinct criteria. The first is an assessment of whether the Kepler signal has a high INTERNAL probability of being a transit signal and not an instrumental or statistical anomaly. The second is an assessment of whether the candidate has a high EXTERNAL reliability against the possible sources of astronomical false positives; that is, non-planetary astrophysical phenomenon such as stellar variability and eclipsing binary stars have been rejected as the source of the transit event with a high degree of confidence. The first of these criteria references only the Kepler data while the second criterion takes into account other Kepler data and external follow-up observations.

Kepler-452 b was originally published as having both high internal and external reliability with the external probability that the planet is real being >99.73% (3-sigma) (Jenkins et al. 2015; http://adsabs.harvard.edu/abs/2015AJ....150...56J). A recent paper (Mullally et al. 2018; http://adsabs.harvard.edu/abs/2018arXiv180311307M) has called into question the internal reliability of the original results, stating that signals similar to Kepler-452 b have a 16–92% chance of being real and, therefore, the Kepler-452 b signal falls below the original claimed threshold of 99.73% (Mullally et al. 2018). The new paper calls attention to the pitfalls associated with the validation of low signal-to-noise events, i.e. the internal reliability. Indeed, the most recent version of the Kepler pipeline assigned Kepler-452 b an intermediate grade for its internal reliability. This new paper has not definitively shown that the Kepler-452 b signal is instrumental in origin. While the external reliability remains high, the internal reliability is lower than what is claimed in the original 2015 paper.

For now, the Exoplanet Archive has opted to retain Kepler-452 b within the Confirmed Planets table until a more definitive refutation is published.


Last updated: 2 April 2018