[en] 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 & 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.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Yu, Liang; Department of Physics, and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
Winn, Joshua N.; Department of Physics, and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
Albrecht, Simon; Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark
Rappaport, Saul; Department of Physics, and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
Bieryla, Allyson; Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA
Dai, Fei; Department of Physics, and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
Delrez, Laetitia ; Université de Liège > Département d'astrophys., géophysique et océanographie (AGO) > Origines Cosmologiques et Astrophysiques (OrCa)
Hillenbrand, Lynne; Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA, 91125, USA
Holman, Matthew J.; Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA
Howard, Andrew W.; Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USA
Huang, Chelsea X.; Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA
Isaacson, Howard; Department of Astronomy, University of California, Berkeley, CA 94720, USA
Jehin, Emmanuel ; Université de Liège > Département d'astrophys., géophysique et océanographie (AGO) > Origines Cosmologiques et Astrophysiques (OrCa)
Lendl, Monika; Institut d’Astrophysique et de Géophysique, Université de Liège, allée du 6 Août 17, B-4000 Liège, Belgium ; Observatoire Astronomique de l’Université de Genève, Chemin des Maillettes 51, CH-1290 Sauverny, Switzerland
Montet, Benjamin T.; Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA ; Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA, 91125, USA
Muirhead, Philip; Department of Astronomy, Boston University, 725 Commonwealth Ave., Boston, MA 02215, USA
Sanchis-Ojeda, Roberto; Department of Astronomy, University of California, Berkeley, CA 94720, USA
Triaud, Amaury H. M. J.; Department of Physics, and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA ; Centre for Planetary Sciences, University of Toronto at Scarborough, 1265 Military Trail, Toronto, ON M1C 1A4, Canada ; Department of Astronomy & Astrophysics, University of Toronto, Toronto, ON M5S 3H4, Canada)
