HATS-37 A b
Astrophysical Synthesis & Habitability Characterization
HATS-37 A b is a confirmed gas giant exoplanet orbiting the star HATS-37 A, located approximately 691.1 light-years (211.9 parsecs) from the Solar System. First announced in 2020 by HATSouth using the Transit detection technique (producing an estimated primary transit depth of 0.5043% across the stellar disk), this world measures 6.793 Earth radii (0.61 Jupiter radii) and has a measured mass of 31.465 Earth masses (0.1 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.55 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.68 g⊕ (6.67 m/s²), and an escape velocity of 24.1 km/s.
In its orbital architecture around HATS-37 A, HATS-37 A b completes one full revolution every 4.332 Earth days at a semi-major axis of 0.04913 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 123.4 km/s (compared to Earth's 29.8 km/s). The orbit is modeled as circular (e = 0.00), maintaining a constant stellar distance throughout its year.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1085 K (+812°C / +1494°F) and receiving 229.70 S⊕ (~312,622 W/m²), HATS-37 A b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HATS-37 A is classified as a stellar host with an effective photospheric temperature of 5,326 K, a radius of 0.877 R☉, a mass of 0.843 M☉, an estimated bolometric luminosity of 0.555 L☉. Stellar evolution modeling indicates an estimated stellar age of 11.46 Gyr and a metallicity of [Fe/H] = 0.051 dex (metal-rich relative to the Sun). From Earth, HATS-37 A shines at apparent V-band magnitude 12.341 (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-37 A |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,326 K |
| Stellar Radius | 0.8770 R☉ |
| Stellar Mass | 0.8430 M☉ |
| Bolometric Luminosity | 0.555 L☉ |
| Metallicity [Fe/H] | 0.051 dex |
| Stellar Age | 11.460 Gyr |
| Apparent Magnitude | V: 12.341 · G: 11.998 |
| System Architecture | 2 Stars, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.049130 AU |
| Orbital Period | 4.332 days |
| Mean Orbital Velocity | 123.4 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.3300° |
| Mean Bulk Density | 0.55 g/cm³ (24.1 km/s vesc) |
| Insolation Flux | 229.7000 S⊕ (~312,622 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 691.100 LY (211.896 pc) |