HD 213519 b
Astrophysical Synthesis & Habitability Characterization
HD 213519 b is a confirmed sub-neptune exoplanet orbiting the star HD 213519, located approximately 133.7 light-years (41 parsecs) from the Solar System. First announced in 2022 by Multiple Observatories using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 2.99 Earth radii and has a measured mass of 9.217 Earth masses. Combining its mass and radius yields a mean bulk density of 1.9 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.03 g⊕ (10.1 m/s²), and an escape velocity of 19.6 km/s.
In its orbital architecture around HD 213519, HD 213519 b completes one full revolution every 11.122 Earth days at a semi-major axis of 0.099 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 96.8 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.413, swinging from 0.0581 AU at periapsis out to 0.1399 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 931 K (+658°C / +1216°F) and receiving 125.38 S⊕ (~170,642 W/m²), HD 213519 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 213519 is classified as a stellar host with an effective photospheric temperature of 5,840 K, a radius of 1.0829 R☉, a mass of 1.05 M☉, an estimated bolometric luminosity of 1.224 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.01 dex (near-solar heavy-element abundance). From Earth, HD 213519 shines at apparent V-band magnitude 7.68 (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: Multiple Observatories · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 213519 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,840 K |
| Stellar Radius | 1.0829 R☉ |
| Stellar Mass | 1.0500 M☉ |
| Bolometric Luminosity | 1.224 L☉ |
| Metallicity [Fe/H] | 0.010 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 7.680 · G: 7.516 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.099000 AU |
| Orbital Period | 11.122 days |
| Mean Orbital Velocity | 96.8 km/s |
| Orbital Eccentricity (e) | 0.41300 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.9 g/cm³ (19.6 km/s vesc) |
| Insolation Flux | 125.3797 S⊕ (~170,642 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 133.700 LY (41.001 pc) |