Gaia 17bpi: An FU Ori-type Outburst

Lynne A. Hillenbrand, Carlos Contreras Peña, Sam Morrell, Tim Naylor, Michael A. Kuhn, Roc M. Cutri, Luisa M. Rebull, Simon Hodgkin, Dirk Froebrich, Amy K. Mainzer

Research output: Contribution to journalArticlepeer-review


We report on the source Gaia 17bpi and identify it as a new, ongoing FU Ori-type outburst, associated with a young stellar object. The optical light curve from Gaia exhibited a 3.5 mag rise with the source appearing to plateau in mid-/late 2018. Mid-infrared observations from NEOWISE also show a >3 mag rise that occurred in two stages, with the second one coincident with the optical brightening, and the first one preceding the optical brightening by ∼1.5 yr. We model the outburst as having started between October and December of 2014. This wavelength-dependent aspect of young star accretion-driven outbursts has never been documented before. Both the mid-infrared and the optical colors of the object become bluer as the outburst proceeds. Optical spectroscopic characteristics in the outburst phase include: a GK-type absorption spectrum, strong wind/outflow in, e.g., Mgb, NaD, Hα, K I, O I, and Ca II profiles, and detection of Li I 6707 Å. The infrared spectrum in the outburst phase is similar to that of an M-type spectrum, notably exhibiting prominent H2O and 12CO (2-0) bandhead absorption in the K band, and likely He I wind in the Y band. The new FU Ori source Gaia 17bpi is associated with a little-studied dark cloud in the galactic plane, located at a distance of 1.27 kpc.
Original languageEnglish
Article number146
JournalThe Astrophysical Journal
Publication statusPublished - 1 Dec 2018


  • circumstellar matter
  • stars: activity
  • stars: general
  • stars: pre-main sequence
  • stars: variables: general
  • stars: winds
  • outflows
  • Astrophysics - Solar and Stellar Astrophysics
  • Astrophysics - Earth and Planetary Astrophysics
  • Astrophysics - Astrophysics of Galaxies


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