HATS-43 b
Astrophysical Synthesis & Habitability Characterization
HATS-43 b is a confirmed gas giant exoplanet orbiting the star HATS-43, located approximately 1181.6 light-years (362.27 parsecs) from the Solar System. First announced in 2018 by HATSouth using the Transit detection technique (producing an estimated primary transit depth of 2.2302% across the stellar disk), this world measures 13.227 Earth radii (1.18 Jupiter radii) and has a measured mass of 82.954 Earth masses (0.26 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 0.47 g⊕ (4.61 m/s²), and an escape velocity of 28 km/s.
In its orbital architecture around HATS-43, HATS-43 b completes one full revolution every 4.389 Earth days at a semi-major axis of 0.04944 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 122.6 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.173 carries the world between 0.0409 AU at periapsis and 0.058 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1003 K (+730°C / +1346°F) and receiving 192.23 S⊕ (~261,629 W/m²), HATS-43 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HATS-43 is classified as a stellar host with an effective photospheric temperature of 5,099 K, a radius of 0.812 R☉, a mass of 0.837 M☉, an estimated bolometric luminosity of 0.4 L☉. Stellar evolution modeling indicates an estimated stellar age of 8.6 Gyr and a metallicity of [Fe/H] = 0.05 dex (near-solar heavy-element abundance). From Earth, HATS-43 shines at apparent V-band magnitude 13.562 (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-43 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,099 K |
| Stellar Radius | 0.8120 R☉ |
| Stellar Mass | 0.8370 M☉ |
| Bolometric Luminosity | 0.4 L☉ |
| Metallicity [Fe/H] | 0.050 dex |
| Stellar Age | 8.600 Gyr |
| Apparent Magnitude | V: 13.562 · G: 13.401 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.049440 AU |
| Orbital Period | 4.389 days |
| Mean Orbital Velocity | 122.6 km/s |
| Orbital Eccentricity (e) | 0.17300 |
| Orbital Inclination (i) | 89.2400° |
| Mean Bulk Density | 0.2 g/cm³ (28 km/s vesc) |
| Insolation Flux | 192.2328 S⊕ (~261,629 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1181.600 LY (362.273 pc) |