Kepler-288 d
Astrophysical Synthesis & Habitability Characterization
Kepler-288 d is a confirmed sub-neptune exoplanet orbiting the star Kepler-288, located approximately 3894.8 light-years (1194.15 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0503% across the stellar disk), this world measures 2.67 Earth radii and has a measured mass of 7.61 Earth masses. Combining its mass and radius yields a mean bulk density of 2.2 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.07 g⊕ (10.49 m/s²), and an escape velocity of 18.9 km/s.
In its orbital architecture around Kepler-288, Kepler-288 d completes one full revolution every 56.634 Earth days at a semi-major axis of 0.287 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 55.1 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 570 K (+297°C / +567°F) and receiving 12.66 S⊕ (~17,229 W/m²), Kepler-288 d orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-288 is classified as a stellar host with an effective photospheric temperature of 5,918 K, a radius of 1.091 R☉, a mass of 0.842 M☉, an estimated bolometric luminosity of 1.31 L☉. Stellar evolution modeling indicates an estimated stellar age of 12.3 Gyr and a metallicity of [Fe/H] = -0.24 dex (metal-poor relative to the Sun). From Earth, Kepler-288 shines at apparent V-band magnitude 15.283 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-288 system is a multi-planet architecture hosting 3 confirmed worlds, with Kepler-288 d sharing its stellar neighborhood alongside Kepler-288 b, Kepler-288 c.
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-288 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,918 K |
| Stellar Radius | 1.0910 R☉ |
| Stellar Mass | 0.8420 M☉ |
| Bolometric Luminosity | 1.31 L☉ |
| Metallicity [Fe/H] | -0.240 dex |
| Stellar Age | 12.300 Gyr |
| Apparent Magnitude | V: 15.283 · G: 15.152 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.287000 AU |
| Orbital Period | 56.634 days |
| Mean Orbital Velocity | 55.1 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.7500° |
| Mean Bulk Density | 2.2 g/cm³ (18.9 km/s vesc) |
| Insolation Flux | 12.6590 S⊕ (~17,229 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 3894.800 LY (1194.150 pc) |