New HST data and modeling reveal a massive planetesimal collision around Fomalhaut

András Gáspár, George H. Rieke

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


The apparent detection of an exoplanet orbiting Fomalhaut was announced in 2008. However, subsequent observations of Fomalhaut b raised questions about its status: Unlike other exoplanets, it is bright in the optical and nondetected in the infrared, and its orbit appears to cross the debris ring around the star without the expected gravitational perturbations. We revisit previously published data and analyze additional Hubble Space Telescope (HST) data, finding that the source is likely on a radial trajectory and has faded and become extended. Dynamical and collisional modeling of a recently produced dust cloud yields results consistent with the observations. Fomalhaut b appears to be a directly imaged catastrophic collision between two large planetesimals in an extrasolar planetary system. Similar events should be very rare in quiescent planetary systems of the age of Fomalhaut, suggesting that we are possibly witnessing the effects of gravitational stirring due to the orbital evolution of hypothetical planet(s) around the star.

Original languageEnglish (US)
Pages (from-to)9712-9722
Number of pages11
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number18
StatePublished - May 5 2020


  • Circumstellar disks
  • Directly imaged planets
  • Extrasolar planets

ASJC Scopus subject areas

  • General


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