HD 20329 b
Astrophysical Synthesis & Habitability Characterization
HD 20329 b is a confirmed super-earth exoplanet orbiting the star HD 20329, located approximately 207.7 light-years (63.68 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 0.0195% across the stellar disk), this world measures 1.72 Earth radii and has a measured mass of 7.42 Earth masses. Combining its mass and radius yields a mean bulk density of 8.04 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 2.51 g⊕ (24.61 m/s²), and an escape velocity of 23.2 km/s.
In its orbital architecture around HD 20329, HD 20329 b completes one full revolution every 0.926 Earth days at a semi-major axis of 0.018 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 211.4 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 2141 K (+1868°C / +3394°F) and receiving 3,474.00 S⊕ (~4,728,114 W/m²), HD 20329 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 20329 is classified as a stellar host with an effective photospheric temperature of 5,596 K, a radius of 1.13 R☉, a mass of 0.9 M☉, an estimated bolometric luminosity of 1.123 L☉. Stellar evolution modeling indicates an estimated stellar age of 11 Gyr and a metallicity of [Fe/H] = -0.07 dex (near-solar heavy-element abundance). From Earth, HD 20329 shines at apparent V-band magnitude 8.76 (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 | HD 20329 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,596 K |
| Stellar Radius | 1.1300 R☉ |
| Stellar Mass | 0.9000 M☉ |
| Bolometric Luminosity | 1.123 L☉ |
| Metallicity [Fe/H] | -0.070 dex |
| Stellar Age | 11.000 Gyr |
| Apparent Magnitude | V: 8.760 · G: 8.591 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.018000 AU |
| Orbital Period | 0.926 days |
| Mean Orbital Velocity | 211.4 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 76.0100° |
| Mean Bulk Density | 8.04 g/cm³ (23.2 km/s vesc) |
| Insolation Flux | 3474.0000 S⊕ (~4,728,114 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 207.700 LY (63.680 pc) |