TOI-789 d
Astrophysical Synthesis & Habitability Characterization
TOI-789 d is a confirmed super-earth exoplanet orbiting the star TOI-789, located approximately 141.6 light-years (43.41 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 0.1197% across the stellar disk), this world measures 1.4 Earth radii and has a measured mass of 6.6 Earth masses. Combining its mass and radius yields a mean bulk density of 13.26 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 3.37 g⊕ (33.05 m/s²), and an escape velocity of 24.3 km/s.
In its orbital architecture around TOI-789, TOI-789 d completes one full revolution every 12.971 Earth days at a semi-major axis of 0.077 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 64.6 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.05 carries the world between 0.0731 AU at periapsis and 0.0809 AU at apoapsis, driving measurable seasonal insolation cycles.
ℹ️ Thermal & Atmospheric Regime: Current photometric and spectroscopic constraints for TOI-789 d place it outside the conservative habitable zone definition pending further atmospheric characterization.
The host star TOI-789 is classified as a low-mass red dwarf of spectral type M3 V with an effective photospheric temperature of 3,471 K, a radius of 0.371 R☉, a mass of 0.358 M☉, an estimated bolometric luminosity of 0.018 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0 dex (near-solar heavy-element abundance). From Earth, TOI-789 shines at apparent V-band magnitude 14.23 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere. The TOI-789 system is a multi-planet architecture hosting 3 confirmed worlds, with TOI-789 d sharing its stellar neighborhood alongside TOI-789 b, TOI-789 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-789 |
| Spectral Type | M3 V |
| Effective Temp (Teff) | 3,471 K |
| Stellar Radius | 0.3710 R☉ |
| Stellar Mass | 0.3580 M☉ |
| Bolometric Luminosity | 0.018 L☉ |
| Metallicity [Fe/H] | 0.000 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 14.230 · G: 13.164 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.077000 AU |
| Orbital Period | 12.971 days |
| Mean Orbital Velocity | 64.6 km/s |
| Orbital Eccentricity (e) | 0.05000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 13.26 g/cm³ (24.3 km/s vesc) |
| Insolation Flux | 3.0000 S⊕ (~4,083 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 141.600 LY (43.407 pc) |