KELT-15 b
Astrophysical Synthesis & Habitability Characterization
KELT-15 b is a confirmed gas giant exoplanet orbiting the star KELT-15, located approximately 1059 light-years (324.68 parsecs) from the Solar System. First announced in 2016 by KELT-South using the Transit detection technique (producing an estimated primary transit depth of 1.0091% across the stellar disk), this world measures 19.504 Earth radii (1.74 Jupiter radii) and has a measured mass of 416.357 Earth masses (1.31 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.31 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.09 g⊕ (10.69 m/s²), and an escape velocity of 51.7 km/s.
In its orbital architecture around KELT-15, KELT-15 b completes one full revolution every 3.329 Earth days at a semi-major axis of 0.04613 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 150.7 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 1642 K (+1369°C / +2496°F) and receiving 1,612.76 S⊕ (~2,194,969 W/m²), KELT-15 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star KELT-15 is classified as a stellar host with an effective photospheric temperature of 6,003 K, a radius of 1.78 R☉, a mass of 2.06 M☉, an estimated bolometric luminosity of 3.692 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.05 dex (near-solar heavy-element abundance). From Earth, KELT-15 shines at apparent V-band magnitude 11.39 (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: KELT-South · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | KELT-15 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 6,003 K |
| Stellar Radius | 1.7800 R☉ |
| Stellar Mass | 2.0600 M☉ |
| Bolometric Luminosity | 3.692 L☉ |
| Metallicity [Fe/H] | 0.050 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 11.390 · G: 11.069 |
| System Architecture | 2 Stars, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.046130 AU |
| Orbital Period | 3.329 days |
| Mean Orbital Velocity | 150.7 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 88.3000° |
| Mean Bulk Density | 0.31 g/cm³ (51.7 km/s vesc) |
| Insolation Flux | 1612.7618 S⊕ (~2,194,969 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1059.000 LY (324.683 pc) |