TOI-1273 b
Astrophysical Synthesis & Habitability Characterization
TOI-1273 b is a confirmed gas giant exoplanet orbiting the star TOI-1273, located approximately 577.7 light-years (177.12 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 0.9212% across the stellar disk), this world measures 11.097 Earth radii (0.99 Jupiter radii) and has a measured mass of 70.558 Earth masses (0.22 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.28 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.57 g⊕ (5.59 m/s²), and an escape velocity of 28.2 km/s.
In its orbital architecture around TOI-1273, TOI-1273 b completes one full revolution every 4.631 Earth days at a semi-major axis of 0.0549 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 129 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.055 carries the world between 0.0519 AU at periapsis and 0.0579 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1211 K (+938°C / +1720°F) and receiving 225.01 S⊕ (~306,243 W/m²), TOI-1273 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-1273 is classified as a stellar host with an effective photospheric temperature of 5,690 K, a radius of 1.06 R☉, a mass of 1.06 M☉, an estimated bolometric luminosity of 1.057 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.1 Gyr and a metallicity of [Fe/H] = 0.07 dex (metal-rich relative to the Sun). From Earth, TOI-1273 shines at apparent V-band magnitude 10.98 (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-1273 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,690 K |
| Stellar Radius | 1.0600 R☉ |
| Stellar Mass | 1.0600 M☉ |
| Bolometric Luminosity | 1.057 L☉ |
| Metallicity [Fe/H] | 0.070 dex |
| Stellar Age | 3.100 Gyr |
| Apparent Magnitude | V: 10.980 · G: 10.866 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.054900 AU |
| Orbital Period | 4.631 days |
| Mean Orbital Velocity | 129 km/s |
| Orbital Eccentricity (e) | 0.05500 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.28 g/cm³ (28.2 km/s vesc) |
| Insolation Flux | 225.0130 S⊕ (~306,243 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 577.700 LY (177.118 pc) |