KELT-3 b
Astrophysical Synthesis & Habitability Characterization
KELT-3 b is a confirmed gas giant exoplanet orbiting the star KELT-3, located approximately 685.7 light-years (210.25 parsecs) from the Solar System. First announced in 2013 by KELT using the Transit detection technique (producing an estimated primary transit depth of 0.8893% across the stellar disk), this world measures 17.486 Earth radii (1.56 Jupiter radii) and has a measured mass of 616.59 Earth masses (1.94 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.64 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 2.02 g⊕ (19.81 m/s²), and an escape velocity of 66.4 km/s.
In its orbital architecture around KELT-3, KELT-3 b completes one full revolution every 2.703 Earth days at a semi-major axis of 0.04123 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 165.9 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 1816 K (+1543°C / +2809°F) and receiving 1,704.57 S⊕ (~2,319,920 W/m²), KELT-3 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star KELT-3 is classified as a stellar host with an effective photospheric temperature of 6,304 K, a radius of 1.7 R☉, a mass of 1.96 M☉, an estimated bolometric luminosity of 4.095 L☉. Stellar evolution modeling indicates an estimated stellar age of 3 Gyr and a metallicity of [Fe/H] = 0.05 dex (near-solar heavy-element abundance). From Earth, KELT-3 shines at apparent V-band magnitude 9.816 (accessible to binoculars and small amateur telescopes) 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 · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | KELT-3 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 6,304 K |
| Stellar Radius | 1.7000 R☉ |
| Stellar Mass | 1.9600 M☉ |
| Bolometric Luminosity | 4.095 L☉ |
| Metallicity [Fe/H] | 0.050 dex |
| Stellar Age | 3.000 Gyr |
| Apparent Magnitude | V: 9.816 · G: 9.763 |
| System Architecture | 2 Stars, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.041230 AU |
| Orbital Period | 2.703 days |
| Mean Orbital Velocity | 165.9 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 84.1400° |
| Mean Bulk Density | 0.64 g/cm³ (66.4 km/s vesc) |
| Insolation Flux | 1704.5700 S⊕ (~2,319,920 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 685.700 LY (210.252 pc) |