HATS-23 b
Astrophysical Synthesis & Habitability Characterization
HATS-23 b is a confirmed gas giant exoplanet orbiting the star HATS-23, located approximately 2084.1 light-years (639 parsecs) from the Solar System. First announced in 2017 by HATSouth using the Transit detection technique (producing an estimated primary transit depth of 2.5414% across the stellar disk), this world measures 20.849 Earth radii (1.86 Jupiter radii) and has a measured mass of 467.21 Earth masses (1.47 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.28 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.07 g⊕ (10.49 m/s²), and an escape velocity of 53 km/s.
In its orbital architecture around HATS-23, HATS-23 b completes one full revolution every 2.161 Earth days at a semi-major axis of 0.03397 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 171.1 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.114 carries the world between 0.0301 AU at periapsis and 0.0378 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1654 K (+1381°C / +2518°F) and receiving 994.80 S⊕ (~1,353,923 W/m²), HATS-23 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HATS-23 is classified as a solar-type yellow star of spectral type G V with an effective photospheric temperature of 5,780 K, a radius of 1.199 R☉, a mass of 1.121 M☉, an estimated bolometric luminosity of 1.44 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.2 Gyr and a metallicity of [Fe/H] = 0.28 dex (metal-rich relative to the Sun). From Earth, HATS-23 shines at apparent V-band magnitude 13.84 (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-23 |
| Spectral Type | G V |
| Effective Temp (Teff) | 5,780 K |
| Stellar Radius | 1.1990 R☉ |
| Stellar Mass | 1.1210 M☉ |
| Bolometric Luminosity | 1.44 L☉ |
| Metallicity [Fe/H] | 0.280 dex |
| Stellar Age | 4.200 Gyr |
| Apparent Magnitude | V: 13.840 · G: 13.752 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.033970 AU |
| Orbital Period | 2.161 days |
| Mean Orbital Velocity | 171.1 km/s |
| Orbital Eccentricity (e) | 0.11400 |
| Orbital Inclination (i) | 81.0200° |
| Mean Bulk Density | 0.28 g/cm³ (53 km/s vesc) |
| Insolation Flux | 994.8004 S⊕ (~1,353,923 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2084.100 LY (639.004 pc) |