HAT-P-53 b
Astrophysical Synthesis & Habitability Characterization
HAT-P-53 b is a confirmed gas giant exoplanet orbiting the star HAT-P-53, located approximately 2174.8 light-years (666.8 parsecs) from the Solar System. First announced in 2015 by HATNet using the Transit detection technique (producing an estimated primary transit depth of 1.2549% across the stellar disk), this world measures 14.773 Earth radii (1.32 Jupiter radii) and has a measured mass of 471.66 Earth masses (1.48 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.81 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 2.16 g⊕ (21.18 m/s²), and an escape velocity of 63.2 km/s.
In its orbital architecture around HAT-P-53, HAT-P-53 b completes one full revolution every 1.962 Earth days at a semi-major axis of 0.03159 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 175.2 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.134 carries the world between 0.0274 AU at periapsis and 0.0358 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1778 K (+1505°C / +2741°F) and receiving 1,400.02 S⊕ (~1,905,431 W/m²), HAT-P-53 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HAT-P-53 is classified as a stellar host with an effective photospheric temperature of 5,956 K, a radius of 1.209 R☉, a mass of 1.093 M☉, an estimated bolometric luminosity of 1.65 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.67 Gyr and a metallicity of [Fe/H] = 0 dex (near-solar heavy-element abundance). From Earth, HAT-P-53 shines at apparent V-band magnitude 13.78 (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-53 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,956 K |
| Stellar Radius | 1.2090 R☉ |
| Stellar Mass | 1.0930 M☉ |
| Bolometric Luminosity | 1.65 L☉ |
| Metallicity [Fe/H] | 0.000 dex |
| Stellar Age | 4.670 Gyr |
| Apparent Magnitude | V: 13.780 · G: 13.514 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.031590 AU |
| Orbital Period | 1.962 days |
| Mean Orbital Velocity | 175.2 km/s |
| Orbital Eccentricity (e) | 0.13400 |
| Orbital Inclination (i) | 86.2000° |
| Mean Bulk Density | 0.81 g/cm³ (63.2 km/s vesc) |
| Insolation Flux | 1400.0226 S⊕ (~1,905,431 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2174.800 LY (666.802 pc) |