WASP-107 b
Reference data for WASP-107 b: 0.94 Jupiter radii at 30.5 Earth masses, 5.72-day orbit in Virgo, JWST internal heat and silicate cloud findings.
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 | 211.6 ly | ± 0.4 ly | Gaia DR3 trigonometric parallax of host star | definitive | ESA Gaia Archive — Data Release 3 |
| Orbital Period | 5.721474 d | ± 0.000002 d | Multi-epoch transit or astrometric orbital fitting | definitive | NASA Exoplanet Archive |
| Semi-Major Axis | 0.0558 AU | ± 0.001 AU | Keplerian third-law solution from stellar mass and orbital period | definitive | NASA Exoplanet Archive |
| Planetary Mass | 30.5 M⊕ | ± 1.7 M⊕ | Keck/HIRES and CORALIE radial velocity monitoring (Piaulet et al. 2021); ~0.096 M♃. | definitive | NASA Exoplanet Archive |
| Planetary Radius | 10.54 R⊕ | ± 0.22 R⊕ | Equivalent to 0.940 ± 0.020 Jupiter radii. | definitive | NASA Exoplanet Archive |
| Equilibrium Temperature | 736 K | ± 15 K | Radiative equilibrium calculation from bolometric stellar insolation | definitive | NASA Exoplanet Archive |
J2000 Equatorial Sky Chart & Culmination Altitude
The chart below plots WASP-107 b — Super-Puff Exoplanet Profile at RA 12h 33m 32.84s, Dec -10° 08′ 46.2″ within Virgo, 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
Discovered in 2017 orbiting an active K6V dwarf in Virgo every 5.721 days, WASP-107 b stands out as one of the lowest-density exoplanets ever weighed. Although its diameter is nearly equal to Jupiter's (0.94 Jupiter radii, or 10.54 Earth radii), precision radial velocity campaigns revealed a mass of only 30.5 Earth masses—roughly 1.8 times the mass of Neptune and less than a tenth that of Jupiter. Its mean density of ~0.13 grams per cubic centimeter gives its atmosphere an enormous pressure scale height, making it a premier target for transmission spectroscopy.
For years, theorists struggled to explain how such a cool, low-mass planet could sustain so puffy a hydrogen-helium envelope without an unphysically tiny solid core. In 2024, panchromatic JWST spectroscopy (NIRCam, NIRSpec, and MIRI) solved the puzzle: the atmosphere exhibits a thousand-fold depletion in methane alongside abundant sulfur dioxide, carbon dioxide, water vapor, and high-altitude silicate sand clouds. These disequilibrium chemical ratios prove that WASP-107 b has an intrinsic internal temperature exceeding 400 K, driven by tidal heating from its slightly eccentric (e ~ 0.06) orbit, which puffs up the atmosphere above a massive ~12-Earth-mass core.
In 2018, WASP-107 b became the first exoplanet with an extended exosphere detected via the infrared 10,830-angstrom metastable helium triplet, revealing a comet-like tail of escaping gas. Long-term radial velocity tracking also uncovered an eccentric outer gas giant, WASP-107 c, on a ~3-year orbit that likely shepherds the inner super-puff into its polar, tidally heated trajectory.
Practical Visual Observing Guide
- Host star WASP-107 shines at visual magnitude V = 11.60 in Virgo.
- Because the K6V host star is small (0.66 R☉) and the planet is Jupiter-sized, transits produce a huge ~2.1% (~0.023 mag) dip over 2.75 hours.
- Easily detected in amateur 8-inch to 14-inch CCD/CMOS transit campaigns.
Catalog Cross-Identifications & Aliases
Common Aliases: WASP-107b · TIC 429302040 b
| Catalog Authority | Identifier |
|---|---|
| NASAEXOPLANET | WASP-107 b |
| SIMBAD | WASP-107 b |
Related Objects, Comparisons & Guides
WASP-76 b — Molten-Iron-Rain Ultra-Hot Jupiter
Reference data for WASP-76 b: 1.85 Jupiter radii, 1.81-day orbit in Pisces, ESPRESSO iron-condensation asymmetry, and glory effect studies.
HD 189733 b — Cobalt-Blue Hot Jupiter Data
Reference profile for HD 189733 b: 2.22-day orbit, 2.4% transit depth in Vulpecula, atmospheric silicate clouds, and JWST H2S detection.
HD 209458 b (Osiris First Transiting Planet)
Coordinates, Gaia DR3 distance (48.3 pc), 3.5247-day transit period, 1.359 R♃ inflated radius, and atmospheric escape data for HD 209458 b.
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