HATS-44 b
Astrophysical Synthesis & Habitability Characterization
HATS-44 b is a confirmed gas giant exoplanet orbiting the star HATS-44, located approximately 1454.8 light-years (446.04 parsecs) from the Solar System. First announced in 2018 by HATSouth using the Transit detection technique (producing an estimated primary transit depth of 1.6759% across the stellar disk), this world measures 11.96 Earth radii (1.07 Jupiter radii) and has a measured mass of 177.985 Earth masses (0.56 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.57 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.24 g⊕ (12.16 m/s²), and an escape velocity of 43.2 km/s.
In its orbital architecture around HATS-44, HATS-44 b completes one full revolution every 2.744 Earth days at a semi-major axis of 0.03649 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 144.7 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.279, swinging from 0.0263 AU at periapsis out to 0.0467 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1161 K (+888°C / +1630°F) and receiving 306.42 S⊕ (~417,034 W/m²), HATS-44 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HATS-44 is classified as a stellar host with an effective photospheric temperature of 5,080 K, a radius of 0.847 R☉, a mass of 0.86 M☉, an estimated bolometric luminosity of 0.429 L☉. Stellar evolution modeling indicates an estimated stellar age of 9.7 Gyr and a metallicity of [Fe/H] = 0.32 dex (metal-rich relative to the Sun). From Earth, HATS-44 shines at apparent V-band magnitude 14.397 (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-44 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,080 K |
| Stellar Radius | 0.8470 R☉ |
| Stellar Mass | 0.8600 M☉ |
| Bolometric Luminosity | 0.429 L☉ |
| Metallicity [Fe/H] | 0.320 dex |
| Stellar Age | 9.700 Gyr |
| Apparent Magnitude | V: 14.397 · G: 14.160 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.036490 AU |
| Orbital Period | 2.744 days |
| Mean Orbital Velocity | 144.7 km/s |
| Orbital Eccentricity (e) | 0.27900 |
| Orbital Inclination (i) | 84.6500° |
| Mean Bulk Density | 0.57 g/cm³ (43.2 km/s vesc) |
| Insolation Flux | 306.4170 S⊕ (~417,034 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1454.800 LY (446.035 pc) |