HATS-1 b
Astrophysical Synthesis & Habitability Characterization
HATS-1 b is a confirmed gas giant exoplanet orbiting the star HATS-1, located approximately 926.2 light-years (283.97 parsecs) from the Solar System. First announced in 2012 by HATSouth using the Transit detection technique (producing an estimated primary transit depth of 1.6615% across the stellar disk), this world measures 14.594 Earth radii (1.3 Jupiter radii) and has a measured mass of 589.55 Earth masses (1.85 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.05 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 2.77 g⊕ (27.16 m/s²), and an escape velocity of 71.1 km/s.
In its orbital architecture around HATS-1, HATS-1 b completes one full revolution every 3.446 Earth days at a semi-major axis of 0.0444 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 140.2 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.12 carries the world between 0.0391 AU at periapsis and 0.0497 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1359 K (+1086°C / +1987°F) and receiving 489.95 S⊕ (~666,817 W/m²), HATS-1 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HATS-1 is classified as a stellar host with an effective photospheric temperature of 5,870 K, a radius of 1.038 R☉, a mass of 0.986 M☉, an estimated bolometric luminosity of 1.148 L☉. Stellar evolution modeling indicates an estimated stellar age of 6 Gyr and a metallicity of [Fe/H] = -0.06 dex (near-solar heavy-element abundance). From Earth, HATS-1 shines at apparent V-band magnitude 12.155 (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-1 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,870 K |
| Stellar Radius | 1.0380 R☉ |
| Stellar Mass | 0.9860 M☉ |
| Bolometric Luminosity | 1.148 L☉ |
| Metallicity [Fe/H] | -0.060 dex |
| Stellar Age | 6.000 Gyr |
| Apparent Magnitude | V: 12.155 · G: 11.936 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.044400 AU |
| Orbital Period | 3.446 days |
| Mean Orbital Velocity | 140.2 km/s |
| Orbital Eccentricity (e) | 0.12000 |
| Orbital Inclination (i) | 85.6000° |
| Mean Bulk Density | 1.05 g/cm³ (71.1 km/s vesc) |
| Insolation Flux | 489.9461 S⊕ (~666,817 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 926.200 LY (283.971 pc) |