KELT-23 A b
Astrophysical Synthesis & Habitability Characterization
KELT-23 A b is a confirmed gas giant exoplanet orbiting the star KELT-23 A, located approximately 411.8 light-years (126.26 parsecs) from the Solar System. First announced in 2019 by KELT-North using the Transit detection technique (producing an estimated primary transit depth of 1.8634% across the stellar disk), this world measures 14.83 Earth radii (1.32 Jupiter radii) and has a measured mass of 298.125 Earth masses (0.94 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.5 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.36 g⊕ (13.34 m/s²), and an escape velocity of 50.2 km/s.
In its orbital architecture around KELT-23 A, KELT-23 A b completes one full revolution every 2.255 Earth days at a semi-major axis of 0.03302 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 159.3 km/s (compared to Earth's 29.8 km/s). The orbit is modeled as circular (e = 0.00), maintaining a constant stellar distance throughout its year.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1561 K (+1288°C / +2350°F) and receiving 991.18 S⊕ (~1,349,000 W/m²), KELT-23 A b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star KELT-23 A is classified as a solar-type yellow star of spectral type G2 V with an effective photospheric temperature of 5,899 K, a radius of 0.996 R☉, a mass of 0.944 M☉, an estimated bolometric luminosity of 1.078 L☉. Stellar evolution modeling indicates an estimated stellar age of 6.4 Gyr and a metallicity of [Fe/H] = -0.105 dex (metal-poor relative to the Sun). From Earth, KELT-23 A shines at apparent V-band magnitude 10.308 (faint and requiring research-grade or CCD telescopic photometry) in the Northern 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: KELT-North · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | KELT-23 A |
| Spectral Type | G2 V |
| Effective Temp (Teff) | 5,899 K |
| Stellar Radius | 0.9960 R☉ |
| Stellar Mass | 0.9440 M☉ |
| Bolometric Luminosity | 1.078 L☉ |
| Metallicity [Fe/H] | -0.105 dex |
| Stellar Age | 6.400 Gyr |
| Apparent Magnitude | V: 10.308 · G: 10.182 |
| System Architecture | 2 Stars, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.033020 AU |
| Orbital Period | 2.255 days |
| Mean Orbital Velocity | 159.3 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 85.3700° |
| Mean Bulk Density | 0.5 g/cm³ (50.2 km/s vesc) |
| Insolation Flux | 991.1830 S⊕ (~1,349,000 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 411.800 LY (126.261 pc) |