HATS-47 b
Astrophysical Synthesis & Habitability Characterization
HATS-47 b is a confirmed gas giant exoplanet orbiting the star HATS-47, located approximately 980.7 light-years (300.67 parsecs) from the Solar System. First announced in 2020 by HATSouth using the Transit detection technique (producing an estimated primary transit depth of 3.0578% across the stellar disk), this world measures 12.52 Earth radii (1.12 Jupiter radii) and has a measured mass of 117.279 Earth masses (0.37 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.33 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.75 g⊕ (7.35 m/s²), and an escape velocity of 34.2 km/s.
In its orbital architecture around HATS-47, HATS-47 b completes one full revolution every 3.923 Earth days at a semi-major axis of 0.04269 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 118.4 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.088 carries the world between 0.0389 AU at periapsis and 0.0464 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 853 K (+580°C / +1076°F) and receiving 87.73 S⊕ (~119,401 W/m²), HATS-47 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HATS-47 is classified as a stellar host with an effective photospheric temperature of 4,512 K, a radius of 0.6564 R☉, a mass of 0.674 M☉, an estimated bolometric luminosity of 0.16 L☉. Stellar evolution modeling indicates an estimated stellar age of 8.1 Gyr and a metallicity of [Fe/H] = -0.113 dex (metal-poor relative to the Sun). From Earth, HATS-47 shines at apparent V-band magnitude 14.602 (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-47 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 4,512 K |
| Stellar Radius | 0.6564 R☉ |
| Stellar Mass | 0.6740 M☉ |
| Bolometric Luminosity | 0.16 L☉ |
| Metallicity [Fe/H] | -0.113 dex |
| Stellar Age | 8.100 Gyr |
| Apparent Magnitude | V: 14.602 · G: 14.400 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.042690 AU |
| Orbital Period | 3.923 days |
| Mean Orbital Velocity | 118.4 km/s |
| Orbital Eccentricity (e) | 0.08800 |
| Orbital Inclination (i) | 87.0800° |
| Mean Bulk Density | 0.33 g/cm³ (34.2 km/s vesc) |
| Insolation Flux | 87.7300 S⊕ (~119,401 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 980.700 LY (300.670 pc) |