HATS-53 b
Astrophysical Synthesis & Habitability Characterization
HATS-53 b is a confirmed gas giant exoplanet orbiting the star HATS-53, located approximately 1910.5 light-years (585.77 parsecs) from the Solar System. First announced in 2017 by HATSouth using the Transit detection technique (producing an estimated primary transit depth of 1.5643% across the stellar disk), this world measures 15.02 Earth radii (1.34 Jupiter radii) and has a measured mass of 189.109 Earth masses (0.6 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.31 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.84 g⊕ (8.24 m/s²), and an escape velocity of 39.7 km/s.
In its orbital architecture around HATS-53, HATS-53 b completes one full revolution every 3.854 Earth days at a semi-major axis of 0.04753 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 134.2 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.33, swinging from 0.0318 AU at periapsis out to 0.0632 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1312 K (+1039°C / +1902°F) and receiving 471.61 S⊕ (~641,861 W/m²), HATS-53 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HATS-53 is classified as a stellar host with an effective photospheric temperature of 5,644 K, a radius of 1.101 R☉, a mass of 0.964 M☉, an estimated bolometric luminosity of 1.104 L☉. Stellar evolution modeling indicates an estimated stellar age of 9 Gyr. From Earth, HATS-53 shines at apparent V-band magnitude 13.944 (faint and requiring research-grade or CCD telescopic photometry) in the Southern 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: HATSouth · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HATS-53 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,644 K |
| Stellar Radius | 1.1010 R☉ |
| Stellar Mass | 0.9640 M☉ |
| Bolometric Luminosity | 1.104 L☉ |
| Metallicity [Fe/H] | — |
| Stellar Age | 9.000 Gyr |
| Apparent Magnitude | V: 13.944 · G: 13.656 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.047530 AU |
| Orbital Period | 3.854 days |
| Mean Orbital Velocity | 134.2 km/s |
| Orbital Eccentricity (e) | 0.33000 |
| Orbital Inclination (i) | 88.7800° |
| Mean Bulk Density | 0.31 g/cm³ (39.7 km/s vesc) |
| Insolation Flux | 471.6100 S⊕ (~641,861 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1910.500 LY (585.770 pc) |