TOI-270 d
Astrophysical Synthesis & Habitability Characterization
TOI-270 d is a confirmed super-earth exoplanet orbiting the star TOI-270, located approximately 73.3 light-years (22.48 parsecs) from the Solar System. First announced in 2019 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.2328% across the stellar disk), this world measures 2 Earth radii and has a measured mass of 4.2 Earth masses. Combining its mass and radius yields a mean bulk density of 2.89 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.05 g⊕ (10.3 m/s²), and an escape velocity of 16.2 km/s.
In its orbital architecture around TOI-270, TOI-270 d completes one full revolution every 11.382 Earth days at a semi-major axis of 0.0721 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 68.9 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.0066 (ranging from 0.0716 AU at periapsis to 0.0726 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 383 K (+110°C / +230°F) and receiving 9.21 S⊕ (~12,540 W/m²), TOI-270 d orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-270 is classified as a low-mass red dwarf of spectral type M3 V with an effective photospheric temperature of 3,506 K, a radius of 0.38 R☉, a mass of 0.386 M☉, an estimated bolometric luminosity of 0.02 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.17 dex (metal-poor relative to the Sun). From Earth, TOI-270 shines at apparent V-band magnitude 12.603 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere. The TOI-270 system is a multi-planet architecture hosting 3 confirmed worlds, with TOI-270 d sharing its stellar neighborhood alongside TOI-270 b, TOI-270 c.
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-270 |
| Spectral Type | M3 V |
| Effective Temp (Teff) | 3,506 K |
| Stellar Radius | 0.3800 R☉ |
| Stellar Mass | 0.3860 M☉ |
| Bolometric Luminosity | 0.02 L☉ |
| Metallicity [Fe/H] | -0.170 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 12.603 · G: 11.631 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.072100 AU |
| Orbital Period | 11.382 days |
| Mean Orbital Velocity | 68.9 km/s |
| Orbital Eccentricity (e) | 0.00660 |
| Orbital Inclination (i) | 89.6800° |
| Mean Bulk Density | 2.89 g/cm³ (16.2 km/s vesc) |
| Insolation Flux | 9.2135 S⊕ (~12,540 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 73.300 LY (22.479 pc) |