PTFO 8-8695: Two Stars, Two Signals, No Planet

Abstract

PTFO 8-8695 (CVSO 30) is a star in the 7-10 million year old Orion-OB1a cluster that shows brightness dips that resemble planetary transits. Although strong evidence against the planet hypothesis has been presented, the possibility remains debated in the literature. To obtain further clues, we inspected data from the NASA Transiting Exoplanet Survey Satellite (TESS) and the ESA Gaia mission. The Gaia data suggest that PTFO 8-8695 is a binary: the photometric data show it to be overluminous with respect to members of its kinematic group, and the astrometric data are inconsistent with a single star. The TESS light curve shows two different photometric periods. The variability is dominated by a sinusoidal signal with a period of 11.98 hr, presumably caused by stellar rotation. Also present is a 10.76 hr signal consisting of a not-quite sinusoid interrupted by hour-long dips, the type of signal previously interpreted as planetary transits. The phase of the dips is nearly 180${}^{\circ }$ away from the phase of the originally reported dips. As noted previously, this makes them difficult to explain as planetary transits. Instead, we believe that PTFO 8-8695 is a pair of young and rapidly rotating M dwarfs, one of which shows the same "transient-dipper" behavior that has been seen in at least 5 other cases. The origin of these transient dips is still unknown but likely involves circumstellar material.

arXiv commentAAS journals submitted. See also: https://doi.org/10.1093/mnras/staa1038

References in corpus (47)

• Gaia Data Release 2. Summary of the contents and survey properties
• The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
• The Gaia mission
• Modules for Experiments in Stellar Astrophysics (MESA)
• The Transiting Exoplanet Survey Satellite
• Modules for Experiments in Stellar Astrophysics (MESA): Giant Planets, Oscillations, Rotation, and Massive Stars
• Modules for Experiments in Stellar Astrophysics (MESA): Binaries, Pulsations, and Explosions
• The 2.5 m Telescope of the Sloan Digital Sky Survey
• Intrinsic Colors, Temperatures, and Bolometric Corrections of Pre-Main Sequence Stars
• Gaia Data Release 2: The astrometric solution
• Sloan Digital Sky Survey IV: Mapping the Milky Way, Nearby Galaxies, and the Distant Universe
• Stellar Multiplicity
• Efficient, uninformative sampling of limb darkening coefficients for two-parameter laws
• Gaia Data Release 2: Photometric content and validation
• The TESS Input Catalog and Candidate Target List
• A Revised Age for Upper Scorpius and The Star-Formation History Among the F-Type Members of the Scorpius-Centaurus OB Association
• The Catalina Surveys Periodic Variable Star Catalog
• Mapping the Shores of the Brown Dwarf Desert II: Multiple Star Formation in Taurus-Auriga
• Target Selection for the SDSS-IV APOGEE-2 Survey
• The Optical-Infrared Extinction Curve and its Variation in the Milky Way
• Gaia Radial Velocity Spectrometer
• Mapping the Shores of the Brown Dwarf Desert I.: Upper Scorpius
• Spitzer observations of the Orion OB1 association: disk census in the low mass stars
• Rotation of Low-Mass Stars in Upper Scorpius and Rho Ophiuchus with K2
• The CIDA Variability Survey of Orion OB1. I: the low-mass population of Ori OB 1a and 1b
• The many-faceted light curves of young disk-bearing stars in Upper Sco and $\rho$ Oph observed by $K2$ Campaign 2
• 25 Orionis: A Kinematically Distinct 10 Myr Old Group in Orion OB1a
• The PTF Orion Project: a Possible Planet Transiting a T-Tauri Star
• Cluster Difference Imaging Photometric Survey. I. Light Curves of Stars in Open Clusters from TESS Sectors 6 & 7
• Kinematic structure in the young Sigma Orionis association
• Measurement of Spin-Orbit Misalignment and Nodal Precession for the Planet around Pre-Main-Sequence Star PTFO 8-8695 From Gravity Darkening
• Orbiting Clouds of Material at the Keplerian Co-Rotation Radius of Rapidly Rotating Low Mass WTTs in Upper Sco
• Complex Rotational Modulation of Rapidly Rotating M-Stars Observed with TESS
• Follow-Up Observations of PTFO 8-8695: A 3 MYr Old T-Tauri Star Hosting a Jupiter-mass Planetary Candidate
• Tests of the planetary hypothesis for PTFO 8-8695b
• More Rapidly Rotating PMS M Dwarfs with Light Curves Suggestive of Orbiting Clouds of Material
• A Transient Transit Signature Associated with the Young Star RIK-210
• YETI observations of the young transiting planet candidate CVSO 30 b
• H-alpha Variability in PTFO8-8695 and the Possible Direct Detection of Emission from a 2 Million Year Old Evaporating Hot Jupiter
• Yes, multi-periodic dwarfs in Upper Scorpius are binaries
• Multi-Color Simultaneous Photometry of the T-Tauri Star Having A Planetary Candidate CVSO 30
• Direct Imaging discovery of a second planet candidate around the possibly transiting planet host CVSO 30
• A reappraisal of parameters for the putative planet PTFO 8-8695b and its potentially precessing parent star
• Revisiting a gravity-darkened and precessing planetary system PTFO 8-8695: spin-orbit non-synchronous case
• Evidence for planetary hypothesis for PTFO 8-8695b with five-year optical/infrared monitoring observations
• Evidence that the planetary candidate CVSO30c is a background star from optical, seeing-limited data
• PTFO 8-8695: Two Stars, Two Signals, No Planet

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• Untangling the Galaxy III: Photometric Search for Pre-main Sequence Stars with Deep Learning
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• YETI follow-up observations of the T Tauri star CVSO30 with transit-like dips