TOI-815 c
Astrophysical Synthesis & Habitability Characterization
TOI-815 c is a confirmed sub-neptune exoplanet orbiting the star TOI-815, located approximately 194.8 light-years (59.71 parsecs) from the Solar System. First announced in 2024 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.0973% across the stellar disk), this world measures 2.62 Earth radii and has a measured mass of 23.5 Earth masses. Combining its mass and radius yields a mean bulk density of 7.2 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 3.42 g⊕ (33.54 m/s²), and an escape velocity of 33.5 km/s.
In its orbital architecture around TOI-815, TOI-815 c completes one full revolution every 34.976 Earth days at a semi-major axis of 0.193 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 60 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.22 carries the world between 0.1505 AU at periapsis and 0.2355 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 469 K (+196°C / +385°F) and receiving 8.03 S⊕ (~10,929 W/m²), TOI-815 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-815 is classified as an orange K-type star of spectral type K3 V with an effective photospheric temperature of 4,869 K, a radius of 0.77 R☉, a mass of 0.776 M☉, an estimated bolometric luminosity of 0.299 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.2 Gyr and a metallicity of [Fe/H] = -0.09 dex (near-solar heavy-element abundance). From Earth, TOI-815 shines at apparent V-band magnitude 10.217 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere. The TOI-815 system is a multi-planet architecture hosting 2 confirmed worlds, with TOI-815 c sharing its stellar neighborhood alongside TOI-815 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-815 |
| Spectral Type | K3 V |
| Effective Temp (Teff) | 4,869 K |
| Stellar Radius | 0.7700 R☉ |
| Stellar Mass | 0.7760 M☉ |
| Bolometric Luminosity | 0.299 L☉ |
| Metallicity [Fe/H] | -0.090 dex |
| Stellar Age | 0.200 Gyr |
| Apparent Magnitude | V: 10.217 · G: 9.940 |
| System Architecture | 2 Stars, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.193000 AU |
| Orbital Period | 34.976 days |
| Mean Orbital Velocity | 60 km/s |
| Orbital Eccentricity (e) | 0.22000 |
| Orbital Inclination (i) | 89.1070° |
| Mean Bulk Density | 7.2 g/cm³ (33.5 km/s vesc) |
| Insolation Flux | 8.0300 S⊕ (~10,929 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 194.800 LY (59.712 pc) |