HAT-P-58 b
Astrophysical Synthesis & Habitability Characterization
HAT-P-58 b is a confirmed gas giant exoplanet orbiting the star HAT-P-58, located approximately 1681.6 light-years (515.59 parsecs) from the Solar System. First announced in 2021 by HATNet using the Transit detection technique (producing an estimated primary transit depth of 0.8003% across the stellar disk), this world measures 14.93 Earth radii (1.33 Jupiter radii) and has a measured mass of 118.232 Earth masses (0.37 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.2 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.53 g⊕ (5.2 m/s²), and an escape velocity of 31.5 km/s.
In its orbital architecture around HAT-P-58, HAT-P-58 b completes one full revolution every 4.014 Earth days at a semi-major axis of 0.04994 AU (an ultra-close orbit less than one-seventh of Mercury's 0.387 AU distance from the Sun, where strong stellar tidal forces typically induce synchronous rotation). Its mean orbital velocity is approximately 135.4 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.073 carries the world between 0.0463 AU at periapsis and 0.0536 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1622 K (+1349°C / +2460°F) and receiving 1,146.00 S⊕ (~1,559,706 W/m²), HAT-P-58 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HAT-P-58 is classified as a stellar host with an effective photospheric temperature of 6,078 K, a radius of 1.53 R☉, a mass of 1.031 M☉, an estimated bolometric luminosity of 2.866 L☉. Stellar evolution modeling indicates an estimated stellar age of 7.11 Gyr and a metallicity of [Fe/H] = -0.224 dex (metal-poor relative to the Sun). From Earth, HAT-P-58 shines at apparent V-band magnitude 12.925 (faint and requiring research-grade or CCD telescopic photometry) 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: HATNet · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HAT-P-58 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 6,078 K |
| Stellar Radius | 1.5300 R☉ |
| Stellar Mass | 1.0310 M☉ |
| Bolometric Luminosity | 2.866 L☉ |
| Metallicity [Fe/H] | -0.224 dex |
| Stellar Age | 7.110 Gyr |
| Apparent Magnitude | V: 12.925 · G: 12.720 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.049940 AU |
| Orbital Period | 4.014 days |
| Mean Orbital Velocity | 135.4 km/s |
| Orbital Eccentricity (e) | 0.07300 |
| Orbital Inclination (i) | 85.6400° |
| Mean Bulk Density | 0.2 g/cm³ (31.5 km/s vesc) |
| Insolation Flux | 1146.0000 S⊕ (~1,559,706 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1681.600 LY (515.590 pc) |