TOI-6729 c
Astrophysical Synthesis & Habitability Characterization
TOI-6729 c is a confirmed sub-neptune exoplanet orbiting the star TOI-6729, located approximately 607.9 light-years (186.38 parsecs) from the Solar System. First announced in 2026 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.0219% across the stellar disk), this world measures 3.01 Earth radii (0.27 Jupiter radii) and has a measured mass of 9.32 Earth masses. Combining its mass and radius yields a mean bulk density of 1.88 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.03 g⊕ (10.1 m/s²), and an escape velocity of 19.7 km/s.
In its orbital architecture around TOI-6729, TOI-6729 c completes one full revolution every 7.837 Earth days. The orbit is modeled as circular (e = 0.00), maintaining a constant stellar distance throughout its year.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1683 K (+1410°C / +2570°F) and receiving 1,330.59 S⊕ (~1,810,938 W/m²), TOI-6729 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-6729 is classified as a stellar host with an effective photospheric temperature of 6,290 K, a radius of 1.8642 R☉, a mass of 1.23 M☉, an estimated bolometric luminosity of 4.881 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.32 dex (metal-poor relative to the Sun). From Earth, TOI-6729 shines at apparent V-band magnitude 9.474 (accessible to binoculars and small amateur telescopes) in the Southern celestial hemisphere. The TOI-6729 system is a multi-planet architecture hosting 2 confirmed worlds, with TOI-6729 c sharing its stellar neighborhood alongside TOI-6729 b.
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-6729 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 6,290 K |
| Stellar Radius | 1.8642 R☉ |
| Stellar Mass | 1.2300 M☉ |
| Bolometric Luminosity | 4.881 L☉ |
| Metallicity [Fe/H] | -0.320 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 9.474 · G: 9.380 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | — |
| Orbital Period | 7.837 days |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.88 g/cm³ (19.7 km/s vesc) |
| Insolation Flux | 1330.5937 S⊕ (~1,810,938 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 607.900 LY (186.378 pc) |