HD 98219 b
Astrophysical Synthesis & Habitability Characterization
HD 98219 b is a confirmed gas giant exoplanet orbiting the star HD 98219, located approximately 370.9 light-years (113.7 parsecs) from the Solar System. First announced in 2011 by W. M. Keck Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.4 Earth radii (1.2 Jupiter radii) and has a measured mass of 624.218 Earth masses (1.96 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.43 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 3.48 g⊕ (34.13 m/s²), and an escape velocity of 76.3 km/s.
In its orbital architecture around HD 98219, HD 98219 b completes one full revolution every 433.8 Earth days (1.19Julian years) at a semi-major axis of 1.26 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 31.6 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.079 carries the world between 1.1605 AU at periapsis and 1.3595 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 454 K (+181°C / +358°F) and receiving 7.05 S⊕ (~9,601 W/m²), HD 98219 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 98219 is classified as an orange K-type star of spectral type K0 III/IV with an effective photospheric temperature of 4,925 K, a radius of 4.6 R☉, a mass of 1.41 M☉, an estimated bolometric luminosity of 11.169 L☉. Stellar evolution modeling indicates an estimated stellar age of 4 Gyr and a metallicity of [Fe/H] = -0.02 dex (near-solar heavy-element abundance). From Earth, HD 98219 shines at apparent V-band magnitude 8.05 (accessible to binoculars and small amateur telescopes) in the Southern 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: W. M. Keck Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 98219 |
| Spectral Type | K0 III/IV |
| Effective Temp (Teff) | 4,925 K |
| Stellar Radius | 4.6000 R☉ |
| Stellar Mass | 1.4100 M☉ |
| Bolometric Luminosity | 11.169 L☉ |
| Metallicity [Fe/H] | -0.020 dex |
| Stellar Age | 4.000 Gyr |
| Apparent Magnitude | V: 8.050 · G: 7.791 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 1.260000 AU |
| Orbital Period | 433.8 days |
| Mean Orbital Velocity | 31.6 km/s |
| Orbital Eccentricity (e) | 0.07900 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.43 g/cm³ (76.3 km/s vesc) |
| Insolation Flux | 7.0547 S⊕ (~9,601 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 370.900 LY (113.704 pc) |