HD 219415 b
Astrophysical Synthesis & Habitability Characterization
HD 219415 b is a confirmed gas giant exoplanet orbiting the star HD 219415, located approximately 538.8 light-years (165.18 parsecs) from the Solar System. First announced in 2012 by McDonald Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.8 Earth radii (1.23 Jupiter radii) and has a measured mass of 317.83 Earth masses (1 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.67 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.67 g⊕ (16.38 m/s²), and an escape velocity of 53.7 km/s.
In its orbital architecture around HD 219415, HD 219415 b completes one full revolution every 2093.3 Earth days (5.73Julian years) at a semi-major axis of 3.2 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 16.6 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.4, swinging from 1.92 AU at periapsis out to 4.48 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 13.800 R⊕, HD 219415 b exceeds the empirical ~1.8–2.2 R⊕ Fulton radius valley threshold, indicating a substantial hydrogen-helium or supercritical volatile envelope without a conventional solid terrestrial surface.
The host star HD 219415 is classified as an orange K-type star of spectral type K0 III with an effective photospheric temperature of 4,820 K, a radius of 2.9 R☉, a mass of 1 M☉, an estimated bolometric luminosity of 4.073 L☉. Stellar evolution modeling indicates an estimated stellar age of 7.233 Gyr and a metallicity of [Fe/H] = -0.04 dex (near-solar heavy-element abundance). From Earth, HD 219415 shines at apparent V-band magnitude 8.909 (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 219415 |
| Spectral Type | K0 III |
| Effective Temp (Teff) | 4,820 K |
| Stellar Radius | 2.9000 R☉ |
| Stellar Mass | 1.0000 M☉ |
| Bolometric Luminosity | 4.073 L☉ |
| Metallicity [Fe/H] | -0.040 dex |
| Stellar Age | 7.233 Gyr |
| Apparent Magnitude | V: 8.909 · G: 8.597 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 3.200000 AU |
| Orbital Period | 2093.3 days |
| Mean Orbital Velocity | 16.6 km/s |
| Orbital Eccentricity (e) | 0.40000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.67 g/cm³ (53.7 km/s vesc) |
| Insolation Flux | 0.4071 S⊕ (~554 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 538.800 LY (165.184 pc) |