Volume 608, December 2017
|Number of page(s)||11|
|Section||Planets and planetary systems|
|Published online||15 December 2017|
Detection of a repeated transit signature in the light curve of the enigma star KIC 8462852: A possible 928-day period
1 Institut d’Astrophysique de Paris, UMR 7095 CNRS, Université Pierre & Marie Curie, 98 bis boulevard Arago, 75014 Paris, France
2 Observatoire de Haute-Provence, CNRS, Université d’Aix-Marseille, 04870 Saint-Michel-l’Observatoire, France
3 Observatoire de Genève, Chemin des Maillettes 51, Sauverny, 1290 Versoix, Switzerland
4 Leiden Observatory, Leiden University, Postbus 9513, 2300 RA Leiden, The Netherlands
Received: 2 June 2017
Accepted: 2 September 2017
As revealed by its peculiar Kepler light curve, the enigmatic star KIC 8462852 undergoes short and deep flux dimmings at a priori unrelated epochs. This star presents nonetheless all other characteristics of a quiet 1 Gyr old F3V star. These dimmings resemble the absorption features expected for the transit of dust cometary tails. The exocomet scenario is therefore most commonly advocated. We reanalysed the Kepler data and extracted a new high-quality light curve to allow for the search of shallow signatures of single or a few exocomets. We discovered that among the 22 flux dimming events that we identified, two events present a striking similarity. These events occurred 928.25 days apart and lasted for 4.4 days with a drop in the star brightness by 1000 ppm. We show that the light curve of these events is well explained by the occultation of the star by a giant ring system or by the transit of a string of half a dozen exocomets with a typical dust production rate of 105–106 kg s-1. Assuming that these two similar events are related to the transit of the same object, we derive a period of 928.25 days. The following transit was expected in March 2017 but bad weather prohibited us from detecting it from ground-based spectroscopy. We predict that the next event will occur between 3−8 October 2019.
Key words: stars: individual: KIC 8462852 / techniques: photometric / comets: general / planets and satellites: rings
© ESO, 2017
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