Return of the King: Time-series Photometry of FO Aquarii’s Initial Recovery from its Unprecedented 2016 Low State - INSU - Institut national des sciences de l'Univers Access content directly
Journal Articles The Astrophysical Journal Year : 2016

Return of the King: Time-series Photometry of FO Aquarii’s Initial Recovery from its Unprecedented 2016 Low State

Colin Littlefield
  • Function : Author
Peter Garnavich
  • Function : Author
Mark R. Kennedy
  • Function : Author
Erin Aadland
  • Function : Author
Donald M. Terndrup
  • Function : Author
Grace V. Calhoun
  • Function : Author
Paul Callanan
  • Function : Author
Jean-Pierre Rivet
Maxime Devogèle
Benjamin Shappee
  • Function : Author
Thomas Holoien
  • Function : Author
Teófilo Arranz Heras
  • Function : Author
Michel Bonnardeau
  • Function : Author
Michael Cook
  • Function : Author
Daniel Coulter
  • Function : Author
André Debackère
  • Function : Author
Shawn Dvorak
  • Function : Author
James R. Foster
  • Function : Author
William Goff
  • Function : Author
Franz-Josef Hambsch
  • Function : Author
Barbara Harris
  • Function : Author
Gordon Myers
Peter Nelson
  • Function : Author
Velimir Popov
  • Function : Author
Rob Solomon
  • Function : Author
William L. Stein
  • Function : Author
Geoff Stone
  • Function : Author
Brad Vietje
  • Function : Author

Abstract

In 2016 May, the intermediate polar FO Aqr was detected in a low state for the first time in its observational history. We report time-resolved photometry of the system during its initial recovery from this faint state. Our data, which includes high-speed photometry with cadences of just 2 s, show the existence of very strong periodicities at 22.5 and 11.26 minutes, equivalent to the spin-orbit beat frequency and twice its value, respectively. A pulse at the spin frequency is also present but at a much lower amplitude than is normally observed in the bright state. By comparing our power spectra with theoretical models, we infer that a substantial amount of accretion was stream-fed during our observations, in contrast to the disk-fed accretion that dominates the bright state. In addition, we find that FO Aqr’s rate of recovery has been unusually slow in comparison to rates of recovery seen in other magnetic cataclysmic variables, with an e-folding time of 115 ± 7 days. The recovery also shows irregular variations in the median brightness of as much as 0.2 mag over a 10-day span. Finally, we show that the arrival times of the spin pulses are dependent upon the system’s overall brightness.

Dates and versions

insu-03689217 , version 1 (07-06-2022)

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Cite

Colin Littlefield, Peter Garnavich, Mark R. Kennedy, Erin Aadland, Donald M. Terndrup, et al.. Return of the King: Time-series Photometry of FO Aquarii’s Initial Recovery from its Unprecedented 2016 Low State. The Astrophysical Journal, 2016, 833, ⟨10.3847/1538-4357/833/1/93⟩. ⟨insu-03689217⟩
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