HD 240237 b
Astrophysical Synthesis & Habitability Characterization
HD 240237 b is a confirmed gas giant exoplanet orbiting the star HD 240237, located approximately 3044.3 light-years (933.38 parsecs) from the Solar System. First announced in 2011 by McDonald Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 12.2 Earth radii (1.09 Jupiter radii) and has a measured mass of 5050.319 Earth masses (15.89 Jupiter masses). Combining its mass and radius yields a mean bulk density of 15.34 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 33.93 g⊕ (332.74 m/s²), and an escape velocity of 227.6 km/s.
In its orbital architecture around HD 240237, HD 240237 b completes one full revolution every 745.7 Earth days (2.04Julian years) at a semi-major axis of 1.92 AU (corresponding to the middle-system regime between Mars at 1.52 AU and Jupiter at 5.20 AU). Its mean orbital velocity is approximately 28 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.4, swinging from 1.152 AU at periapsis out to 2.688 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1153 K (+880°C / +1616°F) and receiving 83.83 S⊕ (~114,092 W/m²), HD 240237 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 240237 is classified as an orange K-type star of spectral type K2 III with an effective photospheric temperature of 3,926 K, a radius of 71.23 R☉, a mass of 8.76 M☉, an estimated bolometric luminosity of 1081.476 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.42 Gyr and a metallicity of [Fe/H] = -0.25 dex (metal-poor relative to the Sun). From Earth, HD 240237 shines at apparent V-band magnitude 8.19 (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: McDonald Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 240237 |
| Spectral Type | K2 III |
| Effective Temp (Teff) | 3,926 K |
| Stellar Radius | 71.2300 R☉ |
| Stellar Mass | 8.7600 M☉ |
| Bolometric Luminosity | 1081.476 L☉ |
| Metallicity [Fe/H] | -0.250 dex |
| Stellar Age | 4.420 Gyr |
| Apparent Magnitude | V: 8.190 · G: 7.493 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 1.920000 AU |
| Orbital Period | 745.7 days |
| Mean Orbital Velocity | 28 km/s |
| Orbital Eccentricity (e) | 0.40000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 15.34 g/cm³ (227.6 km/s vesc) |
| Insolation Flux | 83.8296 S⊕ (~114,092 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 3044.300 LY (933.377 pc) |