HD 145457 b
Astrophysical Synthesis & Habitability Characterization
HD 145457 b is a confirmed gas giant exoplanet orbiting the star HD 145457, located approximately 441.3 light-years (135.29 parsecs) from the Solar System. First announced in 2010 by Subaru Telescope using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.2 Earth radii (1.18 Jupiter radii) and has a measured mass of 888.013 Earth masses (2.79 Jupiter masses). Combining its mass and radius yields a mean bulk density of 2.13 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 5.1 g⊕ (50.01 m/s²), and an escape velocity of 91.7 km/s.
In its orbital architecture around HD 145457, HD 145457 b completes one full revolution every 176.13 Earth days at a semi-major axis of 0.762 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 47.1 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.111 carries the world between 0.6774 AU at periapsis and 0.8466 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 827 K (+554°C / +1029°F) and receiving 77.84 S⊕ (~105,947 W/m²), HD 145457 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 145457 is classified as an orange K-type star of spectral type K0 with an effective photospheric temperature of 4,757 K, a radius of 9.9 R☉, a mass of 1.9 M☉, an estimated bolometric luminosity of 45.029 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.605 Gyr and a metallicity of [Fe/H] = -0.14 dex (metal-poor relative to the Sun). From Earth, HD 145457 shines at apparent V-band magnitude 6.572 (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: Subaru Telescope · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 145457 |
| Spectral Type | K0 |
| Effective Temp (Teff) | 4,757 K |
| Stellar Radius | 9.9000 R☉ |
| Stellar Mass | 1.9000 M☉ |
| Bolometric Luminosity | 45.029 L☉ |
| Metallicity [Fe/H] | -0.140 dex |
| Stellar Age | 2.605 Gyr |
| Apparent Magnitude | V: 6.572 · G: 6.283 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.762000 AU |
| Orbital Period | 176.13 days |
| Mean Orbital Velocity | 47.1 km/s |
| Orbital Eccentricity (e) | 0.11100 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 2.13 g/cm³ (91.7 km/s vesc) |
| Insolation Flux | 77.8446 S⊕ (~105,947 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 441.300 LY (135.292 pc) |