TOI-1355 b
Astrophysical Synthesis & Habitability Characterization
TOI-1355 b is a confirmed gas giant exoplanet orbiting the star TOI-1355, located approximately 809.3 light-years (248.15 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 0.6053% across the stellar disk), this world has a measured radius of 15.962 Earth radii (1.42 R♃), though radial-velocity mass constraints remain unmeasured in the current composite catalogue.
In its orbital architecture around TOI-1355, TOI-1355 b completes one full revolution every 2.17 Earth days at a semi-major axis of 0.04 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 200.5 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.2203 carries the world between 0.0312 AU at periapsis and 0.0488 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 2740 K (+2467°C / +4473°F) and receiving 11,706.95 S⊕ (~15,933,166 W/m²), TOI-1355 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-1355 is classified as a luminous A-type star of spectral type A3 V with an effective photospheric temperature of 8,660 K, a radius of 1.881 R☉, a mass of 2 M☉, an estimated bolometric luminosity of 17.854 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.37 Gyr and a metallicity of [Fe/H] = -0.01 dex (near-solar heavy-element abundance). From Earth, TOI-1355 shines at apparent V-band magnitude 8.72 (accessible to binoculars and small amateur telescopes) 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-1355 |
| Spectral Type | A3 V |
| Effective Temp (Teff) | 8,660 K |
| Stellar Radius | 1.8810 R☉ |
| Stellar Mass | 2.0000 M☉ |
| Bolometric Luminosity | 17.854 L☉ |
| Metallicity [Fe/H] | -0.010 dex |
| Stellar Age | 0.370 Gyr |
| Apparent Magnitude | V: 8.720 · G: 8.707 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.040000 AU |
| Orbital Period | 2.17 days |
| Mean Orbital Velocity | 200.5 km/s |
| Orbital Eccentricity (e) | 0.22030 |
| Orbital Inclination (i) | — |
| Insolation Flux | 11706.9549 S⊕ (~15,933,166 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 809.300 LY (248.148 pc) |