Kepler-878 b
Astrophysical Synthesis & Habitability Characterization
Kepler-878 b is a confirmed super-earth exoplanet orbiting the star Kepler-878, located approximately 2581.9 light-years (791.63 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0528% across the stellar disk), this world measures 1.93 Earth radii and has a measured mass of 4.38 Earth masses. Combining its mass and radius yields a mean bulk density of 3.36 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.18 g⊕ (11.57 m/s²), and an escape velocity of 16.9 km/s.
In its orbital architecture around Kepler-878, Kepler-878 b completes one full revolution every 25.942 Earth days at a semi-major axis of 0.165 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 69.2 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 501 K (+228°C / +442°F) and receiving 27.01 S⊕ (~36,759 W/m²), Kepler-878 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-878 is classified as a stellar host with an effective photospheric temperature of 5,044 K, a radius of 0.77 R☉, a mass of 0.81 M☉, an estimated bolometric luminosity of 0.344 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.57 Gyr and a metallicity of [Fe/H] = -0.03 dex (near-solar heavy-element abundance). From Earth, Kepler-878 shines at apparent V-band magnitude 14.967 (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-878 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,044 K |
| Stellar Radius | 0.7700 R☉ |
| Stellar Mass | 0.8100 M☉ |
| Bolometric Luminosity | 0.344 L☉ |
| Metallicity [Fe/H] | -0.030 dex |
| Stellar Age | 4.570 Gyr |
| Apparent Magnitude | V: 14.967 · G: 14.790 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.165000 AU |
| Orbital Period | 25.942 days |
| Mean Orbital Velocity | 69.2 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.2000° |
| Mean Bulk Density | 3.36 g/cm³ (16.9 km/s vesc) |
| Insolation Flux | 27.0090 S⊕ (~36,759 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2581.900 LY (791.625 pc) |