Kepler-740 b
Astrophysical Synthesis & Habitability Characterization
Kepler-740 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-740, located approximately 4703.2 light-years (1442.02 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.2319% across the stellar disk), this world measures 4.57 Earth radii (0.41 Jupiter radii) and has a measured mass of 18.9 Earth masses. Combining its mass and radius yields a mean bulk density of 1.09 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.9 g⊕ (8.83 m/s²), and an escape velocity of 22.7 km/s.
In its orbital architecture around Kepler-740, Kepler-740 b completes one full revolution every 3.584 Earth days at a semi-major axis of 0.0462 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 140.2 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 1131 K (+858°C / +1576°F) and receiving 432.87 S⊕ (~589,131 W/m²), Kepler-740 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-740 is classified as a stellar host with an effective photospheric temperature of 5,438 K, a radius of 0.87 R☉, a mass of 0.91 M☉, an estimated bolometric luminosity of 0.594 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.79 Gyr and a metallicity of [Fe/H] = 0.03 dex (near-solar heavy-element abundance). From Earth, Kepler-740 shines at apparent V-band magnitude 16.022 (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: Kepler · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | Kepler-740 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,438 K |
| Stellar Radius | 0.8700 R☉ |
| Stellar Mass | 0.9100 M☉ |
| Bolometric Luminosity | 0.594 L☉ |
| Metallicity [Fe/H] | 0.030 dex |
| Stellar Age | 4.790 Gyr |
| Apparent Magnitude | V: 16.022 · G: 15.924 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.046200 AU |
| Orbital Period | 3.584 days |
| Mean Orbital Velocity | 140.2 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.7600° |
| Mean Bulk Density | 1.09 g/cm³ (22.7 km/s vesc) |
| Insolation Flux | 432.8660 S⊕ (~589,131 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 4703.200 LY (1442.020 pc) |