Astrometric Constraints on the Masses of Long-Period Gas Giant Planets in the TRAPPIST-1 Planetary System

Abstract

Transit photometry of the M8V dwarf star TRAPPIST-1 (2MASS J23062928-0502285) has revealed the presence of at least seven planets with masses and radii similar to that of Earth orbiting at distances that might allow liquid water to be present on their surfaces. We have been following TRAPPIST-1 since 2011 with the CAPSCam astrometric camera on the 2.5-m du Pont telescope at the Las Campanas Observatory in Chile. In 2016 we noted that TRAPPIST-1 lies slightly farther away than previously thought, at 12.49 pc, rather than 12.1 pc. Here we examine fifteen epochs of CAPSCam observations of TRAPPIST-1, spanning the five years from 2011 to 2016, and obtain a revised trigonometric distance of $12.56\pm 0.12$ pc. The astrometric data analysis pipeline shows no evidence for a long-period astrometric wobble of TRAPPIST-1. After proper motion and parallax are removed, residuals at the level of $\pm 1.3$ millarcsec (mas) remain. The amplitude of these residuals constrains the masses of any long-period gas giant planets in the TRAPPIST-1 system: no planet more massive than $\sim 4.6M_{Jup}$ orbits with a 1 yr period, and no planet more massive than $\sim 1.6M_{Jup}$ orbits with a 5 yr period. Further refinement of the CAPSCam data analysis pipeline, combined with continued CAPSCam observations, should either detect any long-period planets, or put an even tighter constraint on these mass upper limits.

arXiv comment16 pages, 5 figures, 1 table, in press, Astronomical Journal

References in corpus (23)

• Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1
• A terrestrial planet candidate in a temperate orbit around Proxima Centauri
• Temperate Earth-sized planets transiting a nearby ultracool dwarf star
• Astrometric exoplanet detection with Gaia
• A New Planet Around an M Dwarf: Revealing a Correlation Between Exoplanets and Stellar Mass
• Parametrizing the exoplanet eccentricity distribution with the Beta distribution
• A revised estimate of the occurrence rate of terrestrial planets in the habitable zones around kepler m-dwarfs
• Discovery and Characterization of Transiting SuperEarths Using an All-Sky Transit Survey and Follow-up by the James Webb Space Telescope
• The TRENDS High-Contrast Imaging Survey. IV. The Occurrence Rate of Giant Planets around M-Dwarfs
• Rapid Formation of Gas Giant Planets around M Dwarf Stars
• The HARPS search for southern extra-solar planets. XVII. Super-Earth and Neptune-mass planets in multiple planet systems HD47186 and HD181433
• Astrometric Detection of Giant Planets Around Nearby M Dwarfs: The Gaia Potential
• A Volume-limited Sample of 63 M7--M9.5 Dwarfs I. Space Motion, Kinematic Age, and Lithium
• Performance of the VLT Planet Finder SPHERE I. Photometry and astrometry precision with IRDIS and IFS in laboratory
• Astrometry and radial velocities of the planet host M dwarf GJ 317: new trigonometric distance, metallicity and upper limit to the mass of GJ 317b
• Astrometric planet search around southern ultracool dwarfs I: First results, including parallaxes of 20 M8-L2 dwarfs
• Trigonometric Parallaxes and Proper Motions of 134 Southern Late M, L, and T Dwarfs from the Carnegie Astrometric Planet Search Program
• The Carnegie Astrometric Planet Search Program
• The Solar Neighborhood XXIX: The Habitable Real Estate of our Nearest Stellar Neighbors
• Plausible Compositions of the Seven TRAPPIST-1 Planets Using Long-term Dynamical Simulations
• OGLE-2008-BLG-355Lb: A Massive Planet around A Late type Star
• Keck NIRSPEC Radial Velocity Observations of Late-M dwarfs
• Searching for spectroscopic binaries within transition disk objects

Cited by in corpus (8)

• Stellar parameters for TRAPPIST-1
• Cometary impactors on the TRAPPIST-1 planets can destroy all planetary atmospheres and rebuild secondary atmospheres on planets f, g, h
• An upper limit on late accretion and water delivery in the Trappist-1 exoplanet system
• A Reanalysis of the Fundamental Parameters and Age of TRAPPIST-1
• Habitable planet formation around low-mass stars: Rapid accretion, rapid debris removal and the essential contribution of external giants
• Water delivery to the TRAPPIST-1 planets
• Water transport throughout the TRAPPIST-1 system: the role of planetesimals
• Mathematical encoding within multi-resonant planetary systems as SETI beacons