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Tests of the planetary hypothesis for PTFO 8-8695b

Yu, Liang and Winn, Joshua N. and Gillon, Michaël and Albrecht, Simon and Rappaport, Saul and Bieryla, Allyson and Dai, Fei and Delrez, Laetitia and Hillenbrand, Lynne and Holman, Matthew J. and Howard, Andrew W. and Huang, Chelsea X. and Isaacson, Howard T. and Jehin, Emmanuel and Lendl, Monika and Montet, Benjamin T. and Muirhead, Philip and Sanchis-Ojeda, Roberto and Triaud, Amaury H. M. J. (2015) Tests of the planetary hypothesis for PTFO 8-8695b. Astrophysical Journal, 812 (1). Art. No. 48. ISSN 0004-637X.

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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.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Yu, Liang0000-0003-1667-5427
Winn, Joshua N.0000-0002-4265-047X
Gillon, Michaël0000-0003-1462-7739
Rappaport, Saul0000-0003-3182-5569
Bieryla, Allyson0000-0001-6637-5401
Dai, Fei0000-0002-8958-0683
Delrez, Laetitia0000-0001-6108-4808
Holman, Matthew J.0000-0002-1139-4880
Howard, Andrew W.0000-0001-8638-0320
Huang, Chelsea X.0000-0003-0918-7484
Isaacson, Howard T.0000-0002-0531-1073
Montet, Benjamin T.0000-0001-7516-8308
Muirhead, Philip0000-0002-0638-8822
Sanchis-Ojeda, Roberto0000-0002-6193-972X
Triaud, Amaury H. M. J.0000-0002-5510-8751
Additional Information:© 2015 The American Astronomical Society. Received 2015 July 24; accepted 2015 September 4; published 2015 October 7. We thank the referee, Jason W. Barnes, for his comments on the manuscript. We are grateful to Geoff Marcy for helping to arrange the Keck observations, to Aurélie Fumel for helping with the TRAPPIST observations, and to John Johnson and Jon Swift for attempting to perform photometric observations for this project. We thank Greg Herczeg, Hans Moritz Günther, and Nikku Madhusudhan for helpful discussions, and Julian van Eyken for providing the PTF data in a convenient format. Work by JNW was supported by the NASA Origins program (grant NNX11AG85G). M.G. and E.J. are Research Associates at the Belgian Fund for Scientific Research (Fond National de la Recherche Scientifique, F.R.S-FNRS); L.D. received the support of the F.R.I.A. fund of the FNRS. TRAPPIST is a project funded by the F.R.S-FNRS under grant FRFC 2.5.594.09.F, with the participation of the Swiss National Science Foundation (SNF). B.T.M. is supported by the National Science Foundation Graduate Research Fellowship under grant No. DGE1144469. The authors wish to extend special thanks to those of Hawai’ian ancestry on whose sacred mountain of Mauna Kea we are privileged to be guests. Without their generous hospitality, the Keck observations presented herein would not have been possible. Facilities: FLWO:1.2 m, Magellan:Baade, Euler1.2 m, Keck:I (HIRES), Spitzer.
Group:Palomar Transient Factory
Funding AgencyGrant Number
Fond National de la Recherche Scientifique (FNRS)FRFC 2.5.594.09.F
Swiss National Science Foundation (SNSF)UNSPECIFIED
NSF Graduate Research FellowshipDGE-1144469
Subject Keywords:planetary systems; stars: individual (PTFO 8-8695) ; stars: pre-main sequence
Issue or Number:1
Record Number:CaltechAUTHORS:20151207-092434339
Persistent URL:
Official Citation:Liang Yu et al 2015 ApJ 812 48
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:62635
Deposited By: Ruth Sustaita
Deposited On:08 Dec 2015 16:58
Last Modified:09 Mar 2020 13:18

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