TESTS OF THE PLANETARY HYPOTHESIS FOR PTFO 8-8695b

ABSTRACT 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 predict...

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Bibliographic Details
Published in:The Astrophysical journal 2015-10, Vol.812 (1), p.1-18
Main Authors: Yu, Liang, Winn, Joshua N., Gillon, Michaël, Albrecht, Simon, Rappaport, Saul, Bieryla, Allyson, Dai, Fei, Delrez, Laetitia, Hillenbrand, Lynne, Holman, Matthew J., Howard, Andrew W., Huang, Chelsea X., Isaacson, Howard, Jehin, Emmanuel, Lendl, Monika, Montet, Benjamin T., Muirhead, Philip, Sanchis-Ojeda, Roberto, Triaud, Amaury H. M. J.
Format: Article
Language:English
Subjects:
ABSORPTION SPECTROSCOPY
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
Aérospatiale, astronomie & astrophysique
DIAGRAMS
ECLIPSE
EMISSION SPECTROSCOPY
Fading
INFRARED SPECTRA
Occultation
Orbitals
ORBITS
ORIENTATION
PERIODICITY
Physical, chemical, mathematical & earth Sciences
Physique, chimie, mathématiques & sciences de la terre
planetary systems
PLANETS
PRECESSION
RESOLUTION
Space science, astronomy & astrophysics
Spectroscopy
stars: individual (PTFO 8-8695)
stars: pre-main sequence
STARSPOTS
T TAURI STARS
Transits
VISIBLE RADIATION
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Summary:ABSTRACT 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 H 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.
ISSN:0004-637X
1538-4357
1538-4357
DOI:10.1088/0004-637X/812/1/48