TOI-1291 b
Astrophysical Synthesis & Habitability Characterization
TOI-1291 b is a confirmed sub-neptune exoplanet orbiting the star TOI-1291, located approximately 1396.3 light-years (428.12 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 0.0815% across the stellar disk), this world measures 5.638 Earth radii (0.5 Jupiter radii) and has a measured mass of 27.1 Earth masses. Combining its mass and radius yields a mean bulk density of 0.83 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.85 g⊕ (8.34 m/s²), and an escape velocity of 24.5 km/s.
In its orbital architecture around TOI-1291, TOI-1291 b completes one full revolution every 7.162 Earth days.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1649 K (+1376°C / +2509°F) and receiving 1,230.42 S⊕ (~1,674,602 W/m²), TOI-1291 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-1291 is classified as a stellar host with an effective photospheric temperature of 6,140 K, a radius of 1.8109 R☉, a mass of 1.2 M☉, an estimated bolometric luminosity of 4.182 L☉. From Earth, TOI-1291 shines at apparent V-band magnitude 11.516 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.
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-1291 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 6,140 K |
| Stellar Radius | 1.8109 R☉ |
| Stellar Mass | 1.2000 M☉ |
| Bolometric Luminosity | 4.182 L☉ |
| Metallicity [Fe/H] | — |
| Stellar Age | — |
| Apparent Magnitude | V: 11.516 · G: 11.244 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | — |
| Orbital Period | 7.162 days |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | 88.3839° |
| Mean Bulk Density | 0.83 g/cm³ (24.5 km/s vesc) |
| Insolation Flux | 1230.4200 S⊕ (~1,674,602 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1396.300 LY (428.123 pc) |