HD 233604 b
Astrophysical Synthesis & Habitability Characterization
HD 233604 b is a confirmed gas giant exoplanet orbiting the star HD 233604, located approximately 2762.7 light-years (847.06 parsecs) from the Solar System. First announced in 2013 by McDonald Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 12.7 Earth radii (1.13 Jupiter radii) and has a measured mass of 2089.644 Earth masses (6.57 Jupiter masses). Combining its mass and radius yields a mean bulk density of 5.63 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 12.96 g⊕ (127.09 m/s²), and an escape velocity of 143.5 km/s.
In its orbital architecture around HD 233604, HD 233604 b completes one full revolution every 192 Earth days at a semi-major axis of 0.747 AU (comparable to the inner terrestrial zone between Venus, Earth at 1.00 AU, and Mars at 1.52 AU). Its mean orbital velocity is approximately 42.3 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.05 carries the world between 0.7097 AU at periapsis and 0.7844 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 883 K (+610°C / +1130°F) and receiving 100.78 S⊕ (~137,157 W/m²), HD 233604 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 233604 is classified as an orange K-type star of spectral type K5 with an effective photospheric temperature of 4,791 K, a radius of 10.9 R☉, a mass of 1.5 M☉, an estimated bolometric luminosity of 56.163 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.4 Gyr and a metallicity of [Fe/H] = -0.36 dex (metal-poor relative to the Sun). From Earth, HD 233604 shines at apparent V-band magnitude 10.291 (faint and requiring research-grade or CCD telescopic photometry) 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: McDonald Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 233604 |
| Spectral Type | K5 |
| Effective Temp (Teff) | 4,791 K |
| Stellar Radius | 10.9000 R☉ |
| Stellar Mass | 1.5000 M☉ |
| Bolometric Luminosity | 56.163 L☉ |
| Metallicity [Fe/H] | -0.360 dex |
| Stellar Age | 2.400 Gyr |
| Apparent Magnitude | V: 10.291 · G: 10.105 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.747000 AU |
| Orbital Period | 192 days |
| Mean Orbital Velocity | 42.3 km/s |
| Orbital Eccentricity (e) | 0.05000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 5.63 g/cm³ (143.5 km/s vesc) |
| Insolation Flux | 100.7764 S⊕ (~137,157 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2762.700 LY (847.058 pc) |