HD 80653 b
Astrophysical Synthesis & Habitability Characterization
HD 80653 b is a confirmed super-earth exoplanet orbiting the star HD 80653, located approximately 358.3 light-years (109.86 parsecs) from the Solar System. First announced in 2020 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.0154% across the stellar disk), this world measures 1.621 Earth radii and has a measured mass of 5.61 Earth masses. Combining its mass and radius yields a mean bulk density of 7.26 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 2.13 g⊕ (20.89 m/s²), and an escape velocity of 20.8 km/s.
In its orbital architecture around HD 80653, HD 80653 b completes one full revolution every 0.72 Earth days at a semi-major axis of 0.01657 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 250.5 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 2438 K (+2165°C / +3929°F) and receiving 6,130.00 S⊕ (~8,342,930 W/m²), HD 80653 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 80653 is classified as a solar-type yellow star of spectral type G0 V with an effective photospheric temperature of 5,959 K, a radius of 1.199 R☉, a mass of 1.15 M☉, an estimated bolometric luminosity of 1.626 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.3 Gyr and a metallicity of [Fe/H] = 0.255 dex (metal-rich relative to the Sun). From Earth, HD 80653 shines at apparent V-band magnitude 9.452 (accessible to binoculars and small amateur telescopes) in the Northern celestial hemisphere. The HD 80653 system is a multi-planet architecture hosting 2 confirmed worlds, with HD 80653 b sharing its stellar neighborhood alongside K2-312 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: K2 · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 80653 |
| Spectral Type | G0 V |
| Effective Temp (Teff) | 5,959 K |
| Stellar Radius | 1.1990 R☉ |
| Stellar Mass | 1.1500 M☉ |
| Bolometric Luminosity | 1.626 L☉ |
| Metallicity [Fe/H] | 0.255 dex |
| Stellar Age | 3.300 Gyr |
| Apparent Magnitude | V: 9.452 · G: 9.307 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.016570 AU |
| Orbital Period | 0.72 days |
| Mean Orbital Velocity | 250.5 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 81.7000° |
| Mean Bulk Density | 7.26 g/cm³ (20.8 km/s vesc) |
| Insolation Flux | 6130.0000 S⊕ (~8,342,930 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 358.300 LY (109.860 pc) |