LHS 1140 b
Reference profile for LHS 1140 b: refined mass and radius, 24.7-day habitable-zone orbit in Cetus, water-rich interior, and JWST spectroscopy.
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 | 48.8 ly | ± 0.05 ly | Gaia DR3 trigonometric parallax of host star | definitive | ESA Gaia Archive — Data Release 3 |
| Orbital Period | 24.73696 d | ± 0.00004 d | Multi-epoch transit or astrometric orbital fitting | definitive | NASA Exoplanet Archive |
| Semi-Major Axis | 0.0946 AU | ± 0.0017 AU | Keplerian third-law solution from stellar mass and orbital period | definitive | NASA Exoplanet Archive |
| Planetary Mass | 5.6 M⊕ | ± 0.19 M⊕ | High-precision HARPS and ESPRESSO radial velocity campaign (Cadieux et al. 2024). | definitive | NASA Exoplanet Archive |
| Planetary Radius | 1.73 R⊕ | ± 0.025 R⊕ | Transit depth photometry combined with Gaia stellar radius | definitive | NASA Exoplanet Archive |
| Equilibrium Temperature | 226 K | ± 4 K | Radiative equilibrium calculation from bolometric stellar insolation | high-confidence | NASA Exoplanet Archive |
J2000 Equatorial Sky Chart & Culmination Altitude
The chart below plots LHS 1140 b — Temperate Super-Earth Data at RA 00h 44m 59.33s, Dec -15° 16′ 17.5″ within Cetus, 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
Detected in 2017 by the ground-based MEarth-South transit survey and confirmed with HARPS radial velocities, LHS 1140 b orbits a slowly rotating, magnetically calm M4.5V dwarf just 48.8 light-years away in Cetus. Completing an orbit every 24.737 days at a distance of 0.0946 astronomical units, it receives roughly 43 percent of Earth's solar insolation. An inner rocky companion, LHS 1140 c, circles the same star every 3.78 days.
Early measurements suggested an exceptionally dense iron-rich super-Earth, but ultra-precise ESPRESSO radial velocities combined with TESS, Spitzer, and JWST photometry refined its mass to 5.60 ± 0.19 Earth masses and its radius to 1.730 ± 0.025 Earth radii. The resulting bulk density of 5.9 grams per cubic centimeter falls below what is expected for an Earth-like rocky interior compressed at five times Earth's mass, implying either a 10-to-20 percent water mass fraction or a thin hydrogen-rich envelope.
Near-infrared transmission spectra acquired with JWST NIRISS ruled out a cloud-free, hydrogen-dominated mini-Neptune envelope around LHS 1140 b, favoring a high-mean-molecular-weight secondary atmosphere, potentially rich in nitrogen. If the planet is synchronously rotating with a modest greenhouse atmosphere, general circulation models predict a temperate 'bull's-eye' liquid water ocean spanning several thousand kilometers across its substellar dayside.
Practical Visual Observing Guide
- Host star LHS 1140 has an apparent visual magnitude of V ~ 14.18 (J ~ 9.61) in southern Cetus.
- Produces a 2.0-hour transit every 24.74 days with a depth of ~0.51%, detectable with meter-class ground telescopes.
- The host star's low flare rate and slow 131-day rotation minimize stellar contamination in transmission spectra.
Catalog Cross-Identifications & Aliases
Common Aliases: GJ 3053 b · LHS 1140b · TIC 92226327 b
| Catalog Authority | Identifier |
|---|---|
| NASAEXOPLANET | LHS 1140 b |
| SIMBAD | LHS 1140 b |
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.
TOI-700 d — TESS Habitable-Zone Earth Analog
Reference profile for TOI-700 d: 1.07 Earth radii, 37.4-day habitable-zone orbit in Dorado, insolation metrics, and multi-planet context.
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