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Title: TESTS OF THE PLANETARY HYPOTHESIS FOR PTFO 8-8695b

The T Tauri star PTFO 8-8695 exhibits periodic fading events that have been interpreted as the transits of a giant planet on a precessing orbit. Here we present three tests of the planet hypothesis. First, we sought evidence for the secular changes in light-curve morphology that are predicted to be a consequence of orbital precession. We observed 28 fading events spread over several years and did not see the expected changes. Instead, we found that the fading events are not strictly periodic. Second, we attempted to detect the planet's radiation, based on infrared observations spanning the predicted times of occultations. We ruled out a signal of the expected amplitude. Third, we attempted to detect the Rossiter–McLaughlin effect by performing high-resolution spectroscopy throughout a fading event. No effect was seen at the expected level, ruling out most (but not all) possible orientations for the hypothetical planetary orbit. Our spectroscopy also revealed strong, time-variable, high-velocity Hα and Ca H and K emission features. All these observations cast doubt on the planetary hypothesis, and suggest instead that the fading events represent starspots, eclipses by circumstellar dust, or occultations of an accretion hotspot.
Authors:
; ; ; ;  [1] ; ; ; ;  [2] ;  [3] ; ; ;  [4] ;  [5] ;  [6] ;  [7] ; ;  [8] ;  [9]
  1. Department of Physics, and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)
  2. Institut d’Astrophysique et de Géophysique, Université de Liège, allée du 6 Août 17, B-4000 Liège (Belgium)
  3. Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark)
  4. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)
  5. Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA, 91125 (United States)
  6. Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)
  7. Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)
  8. Department of Astronomy, University of California, Berkeley, CA 94720 (United States)
  9. Department of Astronomy, Boston University, 725 Commonwealth Ave., Boston, MA 02215 (United States)
Publication Date:
OSTI Identifier:
22518842
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 812; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION SPECTROSCOPY; DIAGRAMS; ECLIPSE; EMISSION SPECTROSCOPY; INFRARED SPECTRA; ORBITS; ORIENTATION; PERIODICITY; PLANETS; PRECESSION; RESOLUTION; STARSPOTS; T TAURI STARS; VISIBLE RADIATION