HATS-71 b
Astrophysical Synthesis & Habitability Characterization
HATS-71 b is a confirmed gas giant exoplanet orbiting the star HATS-71, located approximately 457.4 light-years (140.23 parsecs) from the Solar System. First announced in 2020 by HATSouth using the Transit detection technique (producing an estimated primary transit depth of 4.8403% across the stellar disk), this world measures 11.478 Earth radii (1.02 Jupiter radii) and has a measured mass of 117.597 Earth masses (0.37 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.43 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.89 g⊕ (8.73 m/s²), and an escape velocity of 35.8 km/s.
In its orbital architecture around HATS-71, HATS-71 b completes one full revolution every 3.796 Earth days at a semi-major axis of 0.03745 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 107.3 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 587 K (+314°C / +597°F) and receiving 18.08 S⊕ (~24,611 W/m²), HATS-71 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HATS-71 is classified as a low-mass red dwarf of spectral type M3 V with an effective photospheric temperature of 3,405 K, a radius of 0.4783 R☉, a mass of 0.4861 M☉, an estimated bolometric luminosity of 0.028 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.2 Gyr and a metallicity of [Fe/H] = 0.17 dex (metal-rich relative to the Sun). From Earth, HATS-71 shines at apparent V-band magnitude 16.437 (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-71 |
| Spectral Type | M3 V |
| Effective Temp (Teff) | 3,405 K |
| Stellar Radius | 0.4783 R☉ |
| Stellar Mass | 0.4861 M☉ |
| Bolometric Luminosity | 0.028 L☉ |
| Metallicity [Fe/H] | 0.170 dex |
| Stellar Age | 3.200 Gyr |
| Apparent Magnitude | V: 16.437 · G: 15.351 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.037450 AU |
| Orbital Period | 3.796 days |
| Mean Orbital Velocity | 107.3 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 88.8200° |
| Mean Bulk Density | 0.43 g/cm³ (35.8 km/s vesc) |
| Insolation Flux | 18.0832 S⊕ (~24,611 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 457.400 LY (140.225 pc) |