TOI-700 d
Reference profile for TOI-700 d: 1.07 Earth radii, 37.4-day habitable-zone orbit in Dorado, insolation metrics, and multi-planet context.
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 | 101.6 ly | ± 0.1 ly | Gaia DR3 trigonometric parallax of host star | definitive | ESA Gaia Archive — Data Release 3 |
| Orbital Period | 37.42396 d | ± 0.0001 d | Multi-epoch transit or astrometric orbital fitting | definitive | NASA Exoplanet Archive |
| Semi-Major Axis | 0.1633 AU | ± 0.0026 AU | Keplerian third-law solution from stellar mass and orbital period | definitive | NASA Exoplanet Archive |
| Planetary Radius | 1.073 R⊕ | ± 0.06 R⊕ | Transit depth photometry combined with Gaia stellar radius | high-confidence | NASA Exoplanet Archive |
| Estimated Mass | 1.25 M⊕ | ± 0.35 M⊕ | Empirical terrestrial mass-radius estimate; ESPRESSO RV campaigns are ongoing. | model-dependent | NASA Exoplanet Archive |
| Equilibrium Temperature | 269 K | ± 7 K | Radiative equilibrium calculation from bolometric stellar insolation | high-confidence | NASA Exoplanet Archive |
J2000 Equatorial Sky Chart & Culmination Altitude
The chart below plots TOI-700 d — TESS Habitable-Zone Earth Analog at RA 06h 28m 23.23s, Dec -65° 34′ 45.5″ within Dorado, 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
Announced in January 2020 and confirmed with targeted Spitzer Space Telescope infrared photometry, TOI-700 d became the first Earth-sized habitable-zone world discovered by NASA's Transiting Exoplanet Survey Satellite (TESS). Its host star lies 101.6 light-years away in Dorado near the south ecliptic pole, placing the system inside TESS's continuous viewing zone where it was monitored across dozens of consecutive observation sectors.
TOI-700 d is the outermost known member of a four-planet system around its 0.42-solar-mass M2V host. Inside its 37.42-day orbit lie three siblings: an Earth-sized rocky world (b, 9.98 days), a gaseous sub-Neptune (c, 16.05 days), and a 0.95-Earth-radius world (e, 27.81 days) discovered in 2023 inside the optimistic habitable zone. Planet d itself measures 1.073 Earth radii and intercepts 86 percent of Earth's solar flux.
Unlike many active red dwarfs that strip planetary atmospheres with frequent superflares, TOI-700 exhibited zero white-light flares across nearly two years of TESS photometric monitoring and shows very faint X-ray and ultraviolet emission. That quiescent stellar environment dramatically improves the odds that both TOI-700 d and its neighbor TOI-700 e have retained secondary atmospheres over their multi-billion-year lifetimes.
Practical Visual Observing Guide
- Located in Dorado near the south ecliptic pole; host star shines at V ~ 13.15 (I ~ 10.9).
- Transits last 3.2 hours and produce a shallow ~610 ppm dip every 37.42 days.
- Positioned inside the JWST and TESS Southern Continuous Viewing Zones for year-round space access.
Catalog Cross-Identifications & Aliases
Common Aliases: TOI-700d · TIC 150428135 d · 2MASS J06282325-6534456 d
| Catalog Authority | Identifier |
|---|---|
| NASAEXOPLANET | TOI-700 d |
| SIMBAD | TOI-700 d |
Related Objects, Comparisons & Guides
LHS 1140 b — Temperate Super-Earth Data
Reference profile for LHS 1140 b: refined mass and radius, 24.7-day habitable-zone orbit in Cetus, water-rich interior, and JWST spectroscopy.
Kepler-186 f — First Earth-Size Habitable World
Reference data for Kepler-186 f: 1.17 Earth radii, 129.9-day habitable-zone orbit around an M1 dwarf in Cygnus, and insolation metrics.
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.
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.
Celestial Coordinates (RA & Dec) Explained
Practical reference to J2000 equatorial coordinates: Right Ascension (RA in hours, minutes, seconds), Declination (Dec in degrees), and sexagesimal conversion.
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