TOI-261.02
Astrophysical Synthesis & Habitability Characterization
TOI-261.02 is a confirmed sub-neptune exoplanet orbiting the star TOI-261, located approximately 373.4 light-years (114.5 parsecs) from the Solar System. First announced in 2021 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.0546% across the stellar disk), this world measures 3.348 Earth radii (0.3 Jupiter radii) and has a measured mass of 11.2 Earth masses. Combining its mass and radius yields a mean bulk density of 1.65 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1 g⊕ (9.81 m/s²), and an escape velocity of 20.5 km/s.
In its orbital architecture around TOI-261, TOI-261.02 completes one full revolution every 13.039 Earth days.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1008 K (+735°C / +1355°F) and receiving 243.53 S⊕ (~331,439 W/m²), TOI-261.02 orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-261 is classified as a stellar host with an effective photospheric temperature of 5,890 K, a radius of 1.3138 R☉, a mass of 1.069 M☉, an estimated bolometric luminosity of 1.864 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.35 dex (metal-poor relative to the Sun). From Earth, TOI-261 shines at apparent V-band magnitude 9.56 (accessible to binoculars and small amateur telescopes) in the Southern celestial hemisphere. The TOI-261 system is a multi-planet architecture hosting 2 confirmed worlds, with TOI-261.02 sharing its stellar neighborhood alongside TOI-261.01.
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-261 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,890 K |
| Stellar Radius | 1.3138 R☉ |
| Stellar Mass | 1.0690 M☉ |
| Bolometric Luminosity | 1.864 L☉ |
| Metallicity [Fe/H] | -0.350 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 9.560 · G: 9.423 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | — |
| Orbital Period | 13.039 days |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.65 g/cm³ (20.5 km/s vesc) |
| Insolation Flux | 243.5261 S⊕ (~331,439 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 373.400 LY (114.495 pc) |