Early 2017 observations of TRAPPIST-1 with $\text{Spitzer}$

Abstract

The recently detected TRAPPIST-1 planetary system, with its seven planets transiting a nearby ultracool dwarf star, offers the first opportunity to perform comparative exoplanetology of temperate Earth-sized worlds. To further advance our understanding of these planets' compositions, energy budgets, and dynamics, we are carrying out an intensive photometric monitoring campaign of their transits with the $\text{Spitzer Space Telescope}$. In this context, we present 60 new transits of the TRAPPIST-1 planets observed with $\text{Spitzer}$/IRAC in February and March 2017. We combine these observations with previously published $\text{Spitzer}$ transit photometry and perform a global analysis of the resulting extensive dataset. This analysis refines the transit parameters and provides revised values for the planets' physical parameters, notably their radii, using updated properties for the star. As part of our study, we also measure precise transit timings that will be used in a companion paper to refine the planets' masses and compositions using the transit timing variations method. TRAPPIST-1 shows a very low level of low-frequency variability in the IRAC 4.5-$\mu$m band, with a photometric RMS of only 0.11$\%$ at a 123-s cadence. We do not detect any evidence of a (quasi-)periodic signal related to stellar rotation. We also analyze the transit light curves individually, to search for possible variations in the transit parameters of each planet due to stellar variability, and find that the $\text{Spitzer}$ transits of the planets are mostly immune to the effects of stellar variations. These results are encouraging for forthcoming transmission spectroscopy observations of the TRAPPIST-1 planets with the $\text{James Webb Space Telescope}$.

24 pages, 14 figures, 3 tables, accepted for publication in MNRAS

References in corpus (17)

• Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1
• Achieving better than 1 minute accuracy in the Heliocentric and Barycentric Julian Dates
• DHP Framework: Digital Health Passports Using Blockchain -- Use case on international tourism during the COVID-19 pandemic
• The Solar Neighborhood XVII: Parallax Results from the CTIOPI 0.9m Program -- Twenty New Members of the RECONS 10 Parsec Sample
• The Transit Light Curve Project. IX. Evidence for a Smaller Radius of the Exoplanet XO-3b
• Water Vapor in the Spectrum of the Extrasolar Planet HD 189733b: 1. the Transit
• Water Vapour Absorption in the Clear Atmosphere of an exo-Neptune
• Observing the Atmospheres of Known Temperate Earth-sized Planets with JWST
• Abiotic oxygen-dominated atmospheres on terrestrial habitable zone planets
• ACCESS I: An Optical Transmission Spectrum of GJ 1214b Reveals a Heterogeneous Stellar Photosphere
• On Correlated-noise Analyses Applied To Exoplanet Light Curves
• A global analysis of Spitzer and new HARPS data confirms the loneliness and metal-richness of GJ 436 b
• On the Age of the TRAPPIST-1 System
• Reconnaissance of the TRAPPIST-1 exoplanet system in the Lyman-$\alpha$ line
• A Machine Learns to Predict the Stability of Tightly Packed Planetary Systems
• Planet-Planet Occultations in TRAPPIST-1 and Other Exoplanet Systems
• First limits on the occurrence rate of short-period planets orbiting brown dwarfs

Cited by in corpus (16)

• The Detectability and Characterization of the TRAPPIST-1 Exoplanet Atmospheres with JWST
• A review of possible planetary atmospheres in the TRAPPIST-1 system
• Pebble-driven planet formation for TRAPPIST-1 and other compact systems
• TRAPPIST-1: Global Results of the Spitzer Exploration Science Program {\it Red Worlds}
• Spitzer Variability Properties of Low-Gravity L Dwarfs
• Tidal Heating and the Habitability of the TRAPPIST-1 Exoplanets
• Distinguishing between wet and dry atmospheres of TRAPPIST-1 e and f
• Do the TRAPPIST-1 Planets Have Hydrogen-rich Atmospheres?
• Stellar energetic particles in the magnetically turbulent habitable zones of TRAPPIST-1-like planetary systems
• The EBLM Project VI. The mass and radius of five low-mass stars in F+M binaries discovered by the WASP survey
• Tides between the TRAPPIST-1 planets
• Ground-based follow-up observations of TRAPPIST-1 transits in the near-infrared
• Global Analysis of the TRAPPIST Ultra-Cool Dwarf Transit Survey
• Comparative analysis of the influence of Sgr A* and nearby active galactic nuclei on the mass loss of known exoplanets
• The tidal parameters of TRAPPIST-1 b and c
• Simulating Radial Velocity Observations of Trappist-1 with SPIRou