HD 70573 b
Astrophysical Synthesis & Habitability Characterization
HD 70573 b is a confirmed gas giant exoplanet orbiting the star HD 70573, located approximately 193 light-years (59.18 parsecs) from the Solar System. First announced in 2007 by La Silla Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 12.8 Earth radii (1.14 Jupiter radii) and has a measured mass of 1900 Earth masses (5.98 Jupiter masses). Combining its mass and radius yields a mean bulk density of 5 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 11.6 g⊕ (113.76 m/s²), and an escape velocity of 136.3 km/s.
In its orbital architecture around HD 70573, HD 70573 b completes one full revolution every 851.8 Earth days (2.33Julian years) at a semi-major axis of 1.76 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 22.5 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.4, swinging from 1.056 AU at periapsis out to 2.464 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 12.800 R⊕, HD 70573 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 70573 is classified as a solar-type yellow star of spectral type G1-1.5 V with an effective photospheric temperature of 5,737 K, a radius of 0.9769 R☉, a mass of 1 M☉, an estimated bolometric luminosity of 0.928 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.102 Gyr and a metallicity of [Fe/H] = -0.18 dex (metal-poor relative to the Sun). From Earth, HD 70573 shines at apparent V-band magnitude 8.667 (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: La Silla Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 70573 |
| Spectral Type | G1-1.5 V |
| Effective Temp (Teff) | 5,737 K |
| Stellar Radius | 0.9769 R☉ |
| Stellar Mass | 1.0000 M☉ |
| Bolometric Luminosity | 0.928 L☉ |
| Metallicity [Fe/H] | -0.180 dex |
| Stellar Age | 0.102 Gyr |
| Apparent Magnitude | V: 8.667 · G: 8.543 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 1.760000 AU |
| Orbital Period | 851.8 days |
| Mean Orbital Velocity | 22.5 km/s |
| Orbital Eccentricity (e) | 0.40000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 5 g/cm³ (136.3 km/s vesc) |
| Insolation Flux | 0.3222 S⊕ (~439 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 193.000 LY (59.182 pc) |