TRAPPIST-1 f
Reference data for TRAPPIST-1 f: Earth-twin radius, 9.21-day resonant orbit, volatile-rich interior models, and equilibrium temperature.
Provenance-Backed Scientific Measurements
Every measurement below preserves its unit, uncertainty interval, observational method, reference epoch, quality status, and primary catalog source. See Uncertainty & Provenance for how competing measurements are handled.
| Parameter | Value | Uncertainty | Method & Epoch | Quality Status | Source Archive |
|---|---|---|---|---|---|
| Distance | 40.66 ly | ± 0.04 ly | Gaia DR3 trigonometric parallax of host star | definitive | ESA Gaia Archive — Data Release 3 |
| Orbital Period | 9.20754 d | ± 0.00004 d | Multi-epoch transit or astrometric orbital fitting | definitive | NASA Exoplanet Archive |
| Semi-Major Axis | 0.03849 AU | ± 0.00033 AU | Keplerian third-law solution from stellar mass and orbital period | definitive | NASA Exoplanet Archive |
| Planetary Mass | 1.039 M⊕ | ± 0.031 M⊕ | Radial velocity or photodynamical transit-timing variations | definitive | NASA Exoplanet Archive |
| Planetary Radius | 1.045 R⊕ | ± 0.013 R⊕ | Transit depth photometry combined with Gaia stellar radius | definitive | NASA Exoplanet Archive |
| Equilibrium Temperature | 219 K | ± 5 K | Radiative equilibrium calculation from bolometric stellar insolation | high-confidence | NASA Exoplanet Archive |
J2000 Equatorial Sky Chart & Culmination Altitude
The chart below plots TRAPPIST-1 f — Cool Habitable-Zone Exoplanet at RA 23h 06m 29.38s, Dec -05° 02′ 28.5″ within Aquarius, alongside peak meridian transit altitudes for 40°N and 30°S observers. Use the RA/Dec Coordinate Converter to compute exact culmination altitude for your latitude.
Astrophysical Context & Structure
Remarkably close to Earth in both size and mass, TRAPPIST-1 f measures 1.045 Earth radii and 1.039 Earth masses as it circuits its host star every 9.208 days at a distance of 0.0385 astronomical units. Despite matching Earth's bulk mass within four percent, its slightly larger volume yields a mean density near 5.0 grams per cubic centimeter—noticeably lower than Earth's 5.51 grams per cubic centimeter. This deficit implies either a volatile-rich outer shell containing several weight-percent water or a smaller metallic core.
Intercepting roughly 38 percent of the solar constant—slightly less than Mars receives in the Solar System—the planet has a zero-albedo equilibrium temperature of 219 K. Without significant greenhouse warming from carbon dioxide, methane, or collision-induced hydrogen absorption, its surface would freeze into a global snowball state, potentially maintaining a subsurface ocean warmed by radiogenic and tidal dissipation.
Discovered during the 2016 Spitzer Space Telescope campaign, planet f engages in a strong 3:2 mean-motion resonance with inner neighbor e and a 4:3 resonance with outer neighbor g. These close gravitational encounters cause its transit arrival times to oscillate by more than half an hour over multi-year cycles, enabling exquisite mass determinations without radial velocity spectroscopy.
Practical Visual Observing Guide
- Transits recur every 9.21 days and last approximately 63 minutes with a depth of ~6,400 ppm.
- Displays large-amplitude transit timing variations (>30 minutes) due to adjacent 3:2 and 4:3 resonances.
- Prime cold-habitable-zone target for near-infrared transmission spectroscopy.
Catalog Cross-Identifications & Aliases
Common Aliases: TRAPPIST-1f · 2MASS J23062928-0502285 f
| Catalog Authority | Identifier |
|---|---|
| NASAEXOPLANET | TRAPPIST-1 f |
| SIMBAD | TRAPPIST-1 f |
Related Objects, Comparisons & Guides
TRAPPIST-1 e (Temperate Terrestrial World)
Coordinates, Gaia distance (12.47 pc), 6.10-day orbital period, mass 0.692 M⊕, radius 0.920 R⊕, and JWST transit spectroscopy for TRAPPIST-1 e.
TRAPPIST-1 g — Largest TRAPPIST-1 Planet Data
Reference profile for TRAPPIST-1 g: 1.129 Earth radii, 1.321 Earth masses, 12.35-day orbit, and outer habitable-zone conditions.
TRAPPIST-1 d — Sub-Earth Exoplanet Profile
Reference data for TRAPPIST-1 d: sub-Earth mass and radius, 4.05-day period, insolation near the runaway greenhouse boundary, and TTV metrics.
Exoplanet Transit & Radial Velocity Methods
How astronomers detect and characterize exoplanets using photometric transit depth ((Rp/R*)²), Doppler radial velocity (M sin i), and JWST transmission spectra.
Measurement Uncertainty & Optics in Astronomy
How random vs systematic errors, asymmetric error bars, model dependencies, and optical aperture/exit-pupil limits shape astronomical measurements.
Scientific Sources & Dataset Provenance
- NASA Exoplanet Archive (2026-10-01 snapshot): Akeson, R. L., et al. 2013, PASP, 125, 989; NASA Exoplanet Archive (IPAC/Caltech) — NASA Exoplanet Science Institute (NExScI / Caltech / IPAC)
- ESA Gaia Archive — Data Release 3 (DR3 (2022-06-13)): Gaia Collaboration, Vallenari, A., et al. 2023, A&A, 674, A1 (Gaia Data Release 3) — European Space Agency / Gaia DPAC