HATS-27 b
Astrophysical Synthesis & Habitability Characterization
HATS-27 b is a confirmed gas giant exoplanet orbiting the star HATS-27, located approximately 2664.7 light-years (816.99 parsecs) from the Solar System. First announced in 2016 by HATSouth using the Transit detection technique (producing an estimated primary transit depth of 0.7848% across the stellar disk), this world measures 16.814 Earth radii (1.5 Jupiter radii) and has a measured mass of 168.45 Earth masses (0.53 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.2 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.6 g⊕ (5.88 m/s²), and an escape velocity of 35.4 km/s.
In its orbital architecture around HATS-27, HATS-27 b completes one full revolution every 4.637 Earth days at a semi-major axis of 0.0611 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 143.3 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.581, swinging from 0.0256 AU at periapsis out to 0.0966 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1659 K (+1386°C / +2527°F) and receiving 1,342.57 S⊕ (~1,827,242 W/m²), HATS-27 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HATS-27 is classified as a warm F-type star of spectral type F with an effective photospheric temperature of 6,438 K, a radius of 1.74 R☉, a mass of 1.415 M☉, an estimated bolometric luminosity of 4.667 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.3 Gyr and a metallicity of [Fe/H] = 0.09 dex (metal-rich relative to the Sun). From Earth, HATS-27 shines at apparent V-band magnitude 12.782 (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-27 |
| Spectral Type | F |
| Effective Temp (Teff) | 6,438 K |
| Stellar Radius | 1.7400 R☉ |
| Stellar Mass | 1.4150 M☉ |
| Bolometric Luminosity | 4.667 L☉ |
| Metallicity [Fe/H] | 0.090 dex |
| Stellar Age | 2.300 Gyr |
| Apparent Magnitude | V: 12.782 · G: 12.679 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.061100 AU |
| Orbital Period | 4.637 days |
| Mean Orbital Velocity | 143.3 km/s |
| Orbital Eccentricity (e) | 0.58100 |
| Orbital Inclination (i) | 87.3000° |
| Mean Bulk Density | 0.2 g/cm³ (35.4 km/s vesc) |
| Insolation Flux | 1342.5733 S⊕ (~1,827,242 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2664.700 LY (816.988 pc) |