TOI-836 b
Astrophysical Synthesis & Habitability Characterization
TOI-836 b is a confirmed super-earth exoplanet orbiting the star TOI-836, located approximately 89.7 light-years (27.5 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 0.0552% across the stellar disk), this world measures 1.704 Earth radii and has a measured mass of 4.53 Earth masses. Combining its mass and radius yields a mean bulk density of 5.05 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 1.56 g⊕ (15.3 m/s²), and an escape velocity of 18.2 km/s.
In its orbital architecture around TOI-836, TOI-836 b completes one full revolution every 3.817 Earth days at a semi-major axis of 0.0422 AU (an ultra-close orbit less than one-seventh of Mercury's 0.387 AU distance from the Sun, where strong stellar tidal forces typically induce synchronous rotation). Its mean orbital velocity is approximately 120.3 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.053 carries the world between 0.04 AU at periapsis and 0.0444 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 871 K (+598°C / +1108°F) and receiving 78.84 S⊕ (~107,299 W/m²), TOI-836 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-836 is classified as an orange K-type star of spectral type K V with an effective photospheric temperature of 4,552 K, a radius of 0.665 R☉, a mass of 0.678 M☉, an estimated bolometric luminosity of 0.17 L☉. Stellar evolution modeling indicates an estimated stellar age of 5.4 Gyr and a metallicity of [Fe/H] = -0.284 dex (metal-poor relative to the Sun). From Earth, TOI-836 shines at apparent V-band magnitude 9.92 (accessible to binoculars and small amateur telescopes) in the Southern celestial hemisphere. The TOI-836 system is a multi-planet architecture hosting 2 confirmed worlds, with TOI-836 b sharing its stellar neighborhood alongside TOI-836.01.
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-836 |
| Spectral Type | K V |
| Effective Temp (Teff) | 4,552 K |
| Stellar Radius | 0.6650 R☉ |
| Stellar Mass | 0.6780 M☉ |
| Bolometric Luminosity | 0.17 L☉ |
| Metallicity [Fe/H] | -0.284 dex |
| Stellar Age | 5.400 Gyr |
| Apparent Magnitude | V: 9.920 · G: 9.405 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.042200 AU |
| Orbital Period | 3.817 days |
| Mean Orbital Velocity | 120.3 km/s |
| Orbital Eccentricity (e) | 0.05300 |
| Orbital Inclination (i) | 87.5700° |
| Mean Bulk Density | 5.05 g/cm³ (18.2 km/s vesc) |
| Insolation Flux | 78.8380 S⊕ (~107,299 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 89.700 LY (27.502 pc) |