TOI-1246 d
Astrophysical Synthesis & Habitability Characterization
TOI-1246 d is a confirmed sub-neptune exoplanet orbiting the star TOI-1246, located approximately 552.6 light-years (169.42 parsecs) from the Solar System. First announced in 2022 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.1323% across the stellar disk), this world measures 3.431 Earth radii (0.31 Jupiter radii) and has a measured mass of 5.4 Earth masses. Combining its mass and radius yields a mean bulk density of 0.74 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.46 g⊕ (4.51 m/s²), and an escape velocity of 14 km/s.
In its orbital architecture around TOI-1246, TOI-1246 d completes one full revolution every 18.655 Earth days at a semi-major axis of 0.132 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 77 km/s (compared to Earth's 29.8 km/s). 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 588 K (+315°C / +599°F) and receiving 28.00 S⊕ (~38,108 W/m²), TOI-1246 d orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-1246 is classified as an orange K-type star of spectral type K V with an effective photospheric temperature of 5,213 K, a radius of 0.8649 R☉, a mass of 0.8889 M☉, an estimated bolometric luminosity of 0.496 L☉. Stellar evolution modeling indicates an estimated stellar age of 6.3 Gyr and a metallicity of [Fe/H] = 0.168 dex (metal-rich relative to the Sun). From Earth, TOI-1246 shines at apparent V-band magnitude 11.632 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The TOI-1246 system is a multi-planet architecture hosting 4 confirmed worlds, with TOI-1246 d sharing its stellar neighborhood alongside TOI-1246 b, TOI-1246 c, TOI-1246 e.
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-1246 |
| Spectral Type | K V |
| Effective Temp (Teff) | 5,213 K |
| Stellar Radius | 0.8649 R☉ |
| Stellar Mass | 0.8889 M☉ |
| Bolometric Luminosity | 0.496 L☉ |
| Metallicity [Fe/H] | 0.168 dex |
| Stellar Age | 6.300 Gyr |
| Apparent Magnitude | V: 11.632 · G: 11.729 |
| System Architecture | 1 Star, 4 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.132000 AU |
| Orbital Period | 18.655 days |
| Mean Orbital Velocity | 77 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.5000° |
| Mean Bulk Density | 0.74 g/cm³ (14 km/s vesc) |
| Insolation Flux | 28.0000 S⊕ (~38,108 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 552.600 LY (169.422 pc) |