TOI-784 b
Astrophysical Synthesis & Habitability Characterization
TOI-784 b is a confirmed super-earth exoplanet orbiting the star HD 307842, located approximately 210.7 light-years (64.6 parsecs) from the Solar System. First announced in 2023 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.0381% across the stellar disk), this world measures 1.93 Earth radii and has a measured mass of 9.67 Earth masses. Combining its mass and radius yields a mean bulk density of 7.42 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 2.6 g⊕ (25.5 m/s²), and an escape velocity of 25 km/s.
In its orbital architecture around HD 307842, TOI-784 b completes one full revolution every 2.797 Earth days at a semi-major axis of 0.038 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 147.8 km/s (compared to Earth's 29.8 km/s). The orbit is modeled as circular (e = 0.00), maintaining a constant stellar distance throughout its year.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1256 K (+983°C / +1801°F) and receiving 413.89 S⊕ (~563,310 W/m²), TOI-784 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 307842 is classified as a solar-type yellow star of spectral type G with an effective photospheric temperature of 5,558 K, a radius of 0.907 R☉, a mass of 0.91 M☉, an estimated bolometric luminosity of 0.704 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.13 dex (metal-poor relative to the Sun). From Earth, HD 307842 shines at apparent V-band magnitude 9.412 (accessible to binoculars and small amateur telescopes) 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 | HD 307842 |
| Spectral Type | G |
| Effective Temp (Teff) | 5,558 K |
| Stellar Radius | 0.9070 R☉ |
| Stellar Mass | 0.9100 M☉ |
| Bolometric Luminosity | 0.704 L☉ |
| Metallicity [Fe/H] | -0.130 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 9.412 · G: 9.235 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.038000 AU |
| Orbital Period | 2.797 days |
| Mean Orbital Velocity | 147.8 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 88.6000° |
| Mean Bulk Density | 7.42 g/cm³ (25 km/s vesc) |
| Insolation Flux | 413.8940 S⊕ (~563,310 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 210.700 LY (64.600 pc) |