TOI-139 b
Astrophysical Synthesis & Habitability Characterization
TOI-139 b is a confirmed sub-neptune exoplanet orbiting the star TOI-139, located approximately 138.3 light-years (42.41 parsecs) from the Solar System. First announced in 2023 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.1033% across the stellar disk), this world measures 2.457 Earth radii and has a measured mass of 6.6 Earth masses. Combining its mass and radius yields a mean bulk density of 2.45 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.09 g⊕ (10.69 m/s²), and an escape velocity of 18.3 km/s.
In its orbital architecture around TOI-139, TOI-139 b completes one full revolution every 11.071 Earth days.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 561 K (+288°C / +550°F) and receiving 22.42 S⊕ (~30,516 W/m²), TOI-139 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-139 is classified as a stellar host with an effective photospheric temperature of 4,570 K, a radius of 0.7007 R☉, a mass of 0.69 M☉, an estimated bolometric luminosity of 0.192 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.238 dex (metal-poor relative to the Sun). From Earth, TOI-139 shines at apparent V-band magnitude 10.55 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere.
Methodology: Computed using the Schulze-Makuch et al. (2011) weighted metric comparing physical interior (radius, estimated density) and surface thermal regime (escape velocity, equilibrium temperature).
Discovery Facility: Transiting Exoplanet Survey Satellite (TESS) · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | TOI-139 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 4,570 K |
| Stellar Radius | 0.7007 R☉ |
| Stellar Mass | 0.6900 M☉ |
| Bolometric Luminosity | 0.192 L☉ |
| Metallicity [Fe/H] | -0.238 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 10.550 · G: 10.077 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | — |
| Orbital Period | 11.071 days |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | 89.3200° |
| Mean Bulk Density | 2.45 g/cm³ (18.3 km/s vesc) |
| Insolation Flux | 22.4219 S⊕ (~30,516 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 138.300 LY (42.406 pc) |