TOI-277 b
Astrophysical Synthesis & Habitability Characterization
TOI-277 b is a confirmed sub-neptune exoplanet orbiting the star TOI-277, located approximately 210.9 light-years (64.67 parsecs) from the Solar System. First announced in 2022 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.4504% across the stellar disk), this world measures 2.65 Earth radii and has a measured mass of 7.51 Earth masses. Combining its mass and radius yields a mean bulk density of 2.23 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.07 g⊕ (10.49 m/s²), and an escape velocity of 18.8 km/s.
In its orbital architecture around TOI-277, TOI-277 b completes one full revolution every 3.994 Earth days at a semi-major axis of 0.0269 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 73.3 km/s (compared to Earth's 29.8 km/s).
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 588 K (+315°C / +599°F) and receiving 28.24 S⊕ (~38,429 W/m²), TOI-277 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-277 is classified as a stellar host with an effective photospheric temperature of 4,031 K, a radius of 0.362 R☉, a mass of 0.16 M☉, an estimated bolometric luminosity of 0.031 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.01 dex (near-solar heavy-element abundance). From Earth, TOI-277 shines at apparent V-band magnitude 13.632 (faint and requiring research-grade or CCD telescopic photometry) in the Southern 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-277 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 4,031 K |
| Stellar Radius | 0.3620 R☉ |
| Stellar Mass | 0.1600 M☉ |
| Bolometric Luminosity | 0.031 L☉ |
| Metallicity [Fe/H] | -0.010 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 13.632 · G: 12.790 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.026900 AU |
| Orbital Period | 3.994 days |
| Mean Orbital Velocity | 73.3 km/s |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | 88.9000° |
| Mean Bulk Density | 2.23 g/cm³ (18.8 km/s vesc) |
| Insolation Flux | 28.2360 S⊕ (~38,429 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 210.900 LY (64.669 pc) |