HATS-3 b
Astrophysical Synthesis & Habitability Characterization
HATS-3 b is a confirmed gas giant exoplanet orbiting the star HATS-3, located approximately 1341.2 light-years (411.21 parsecs) from the Solar System. First announced in 2013 by HATSouth using the Transit detection technique (producing an estimated primary transit depth of 1.0218% across the stellar disk), this world measures 15.48 Earth radii (1.38 Jupiter radii) and has a measured mass of 340.382 Earth masses (1.07 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.51 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.42 g⊕ (13.93 m/s²), and an escape velocity of 52.5 km/s.
In its orbital architecture around HATS-3, HATS-3 b completes one full revolution every 3.548 Earth days at a semi-major axis of 0.0485 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 148.7 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 1648 K (+1375°C / +2507°F) and receiving 1,212.00 S⊕ (~1,649,538 W/m²), HATS-3 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HATS-3 is classified as a warm F-type star of spectral type F with an effective photospheric temperature of 6,351 K, a radius of 1.404 R☉, a mass of 1.209 M☉, an estimated bolometric luminosity of 2.877 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.2 Gyr and a metallicity of [Fe/H] = -0.157 dex (metal-poor relative to the Sun). From Earth, HATS-3 shines at apparent V-band magnitude 12.433 (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-3 |
| Spectral Type | F |
| Effective Temp (Teff) | 6,351 K |
| Stellar Radius | 1.4040 R☉ |
| Stellar Mass | 1.2090 M☉ |
| Bolometric Luminosity | 2.877 L☉ |
| Metallicity [Fe/H] | -0.157 dex |
| Stellar Age | 3.200 Gyr |
| Apparent Magnitude | V: 12.433 · G: 11.891 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.048500 AU |
| Orbital Period | 3.548 days |
| Mean Orbital Velocity | 148.7 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 86.2000° |
| Mean Bulk Density | 0.51 g/cm³ (52.5 km/s vesc) |
| Insolation Flux | 1212.0044 S⊕ (~1,649,538 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1341.200 LY (411.211 pc) |