Secular dimming of KIC 8462852 following its consumption of a planet

Brian D. Metzger*, Ken J. Shen, Nicholas Stone

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

27 Scopus citations

Abstract

The Kepler-field star KIC 8462852, an otherwise apparently ordinary F3 main-sequence star, showed several highly unusual dimming events of variable depth and duration. Adding to the mystery was the discovery that KIC 8462852 faded by 14 per cent from 1890 to 1989, as well as by another 3 per cent over the 4 yr Kepler mission. Following an initial suggestion byWright & Sigurdsson, we propose that the secular dimming behaviour is the result of the inspiral of a planetary body or bodies into KIC 8462852, which took place ~10-104 yr ago (depending on the planet mass). Gravitational energy released as the body inspirals into the outer layers of the star caused a temporary and unobserved brightening, from which the stellar flux is now returning to the quiescent state. The transient dimming events could then be due to obscuration by planetary debris from an earlier partial disruption of the same inspiralling bodies, or due to evaporation and outgassing from a tidally detached moon system. Alternatively, the dimming events could arise from a large number of comet- or planetesimal-mass bodies placed on to high-eccentricity orbits by the samemechanism (e.g. Lidov-Kozai oscillations due to the outer M-dwarf companion) responsible for driving the more massive planets into KIC 8462852. The required high occurrence rate of KIC 8462852-like systems that have undergone recent major planet inspiral event(s) is the greatest challenge to the model, placing large lower limits on the mass of planetary systems surrounding F stars and/or requiring an unlikely probability to catch KIC 8462852 in its current state.

Original languageAmerican English
Pages (from-to)4399-4407
Number of pages9
JournalMonthly Notices of the Royal Astronomical Society
Volume468
Issue number4
DOIs
StatePublished - 1 Jul 2017
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2017 Oxford University Press. All rights reserved.

Keywords

  • Stars: individual: KIC 8462852
  • Stars: variables: general

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