Kepler-272 d
Astrophysical Synthesis & Habitability Characterization
Kepler-272 d is a confirmed sub-neptune exoplanet orbiting the star Kepler-272, located approximately 2901.5 light-years (889.61 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0493% across the stellar disk), this world measures 2.25 Earth radii and has a measured mass of 5.69 Earth masses. Combining its mass and radius yields a mean bulk density of 2.75 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.12 g⊕ (10.98 m/s²), and an escape velocity of 17.8 km/s.
In its orbital architecture around Kepler-272, Kepler-272 d completes one full revolution every 10.937 Earth days at a semi-major axis of 0.091 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 90.5 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 777 K (+504°C / +939°F) and receiving 141.14 S⊕ (~192,085 W/m²), Kepler-272 d orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-272 is classified as a stellar host with an effective photospheric temperature of 5,297 K, a radius of 0.929 R☉, a mass of 0.91 M☉, an estimated bolometric luminosity of 0.61 L☉. Stellar evolution modeling indicates an estimated stellar age of 13.18 Gyr and a metallicity of [Fe/H] = 0.04 dex (near-solar heavy-element abundance). From Earth, Kepler-272 shines at apparent V-band magnitude 14.811 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-272 system is a multi-planet architecture hosting 3 confirmed worlds, with Kepler-272 d sharing its stellar neighborhood alongside Kepler-272 b, Kepler-272 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-272 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,297 K |
| Stellar Radius | 0.9290 R☉ |
| Stellar Mass | 0.9100 M☉ |
| Bolometric Luminosity | 0.61 L☉ |
| Metallicity [Fe/H] | 0.040 dex |
| Stellar Age | 13.180 Gyr |
| Apparent Magnitude | V: 14.811 · G: 14.659 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.091000 AU |
| Orbital Period | 10.937 days |
| Mean Orbital Velocity | 90.5 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 86.6300° |
| Mean Bulk Density | 2.75 g/cm³ (17.8 km/s vesc) |
| Insolation Flux | 141.1350 S⊕ (~192,085 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2901.500 LY (889.608 pc) |