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Transit timing variations in the WASP-4 planetary system

Research output: Contribution to journalArticle

  • John Southworth
  • M. Dominik
  • U. G. Jorgensen
  • M. I. Andersen
  • V. Bozza
  • M. J. Burgdorf
  • G. D'Ago
  • S. Dib
  • R. Figuera Jaimes
  • Y. I. Fujii
  • S. Gill
  • L. K. Haikala
  • T. C. Hinse
  • M. Hundertmark
  • E. Khalouei
  • H. Korhonen
  • P. Longa-Pena
  • L. Mancini
  • N. Peixinho
  • M. Rabus
  • S. Rahvar
  • S. Sajadian
  • J. Skottfelt
  • P. Spyratos
  • J. Tregloan-Reed
  • E. Unda-Sanzana
  • C. von Essen

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Original languageEnglish
Number of pages7
JournalMonthly Notices of the Royal Astronomical Society
Publication statusPublished - 19 Sep 2019


Transits in the planetary system WASP-4 were recently found to occur 80 s earlier than expected in observations from the TESS satellite. We present 22 new times of mid-transit that confirm the existence of transit timing variations, and are well fitted by a quadratic ephemeris with period decay dP/dt = −9.2 ± 1.1 ms yr−1. We rule out instrumental issues, stellar activity and the Applegate mechanism as possible causes. The light-time effect is also not favoured due to the non-detection of changes in the systemic velocity. Orbital decay and apsidal precession are plausible but unproven. WASP-4 b is only the third hot Jupiter known to show transit timing variations to high confidence. We discuss a variety of observations of this and other planetary systems that would be useful in improving our understanding of WASP-4 in particular and orbital decay in general.

    Research areas

  • astro-ph.EP

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