HATS-61 b
Astrophysical Synthesis & Habitability Characterization
HATS-61 b is a confirmed gas giant exoplanet orbiting the star HATS-61, located approximately 2217.1 light-years (679.76 parsecs) from the Solar System. First announced in 2018 by HATSouth using the Transit detection technique (producing an estimated primary transit depth of 0.5447% across the stellar disk), this world measures 13.395 Earth radii (1.2 Jupiter radii) and has a measured mass of 1080.622 Earth masses (3.4 Jupiter masses). Combining its mass and radius yields a mean bulk density of 2.48 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 6.02 g⊕ (59.04 m/s²), and an escape velocity of 100.5 km/s.
In its orbital architecture around HATS-61, HATS-61 b completes one full revolution every 7.818 Earth days at a semi-major axis of 0.07908 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 110 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.092 carries the world between 0.0718 AU at periapsis and 0.0864 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1226 K (+953°C / +1747°F) and receiving 374.20 S⊕ (~509,286 W/m²), HATS-61 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HATS-61 is classified as a stellar host with an effective photospheric temperature of 5,542 K, a radius of 1.664 R☉, a mass of 1.076 M☉, an estimated bolometric luminosity of 2.343 L☉. Stellar evolution modeling indicates an estimated stellar age of 8.9 Gyr and a metallicity of [Fe/H] = 0.247 dex (metal-rich relative to the Sun). From Earth, HATS-61 shines at apparent V-band magnitude 13.352 (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-61 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,542 K |
| Stellar Radius | 1.6640 R☉ |
| Stellar Mass | 1.0760 M☉ |
| Bolometric Luminosity | 2.343 L☉ |
| Metallicity [Fe/H] | 0.247 dex |
| Stellar Age | 8.900 Gyr |
| Apparent Magnitude | V: 13.352 · G: 13.068 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.079080 AU |
| Orbital Period | 7.818 days |
| Mean Orbital Velocity | 110 km/s |
| Orbital Eccentricity (e) | 0.09200 |
| Orbital Inclination (i) | 87.1500° |
| Mean Bulk Density | 2.48 g/cm³ (100.5 km/s vesc) |
| Insolation Flux | 374.2000 S⊕ (~509,286 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2217.100 LY (679.761 pc) |