Kepler-553 c
Astrophysical Synthesis & Habitability Characterization
Kepler-553 c is a confirmed gas giant exoplanet orbiting the star Kepler-553, located approximately 2376.1 light-years (728.53 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 1.3851% across the stellar disk), this world measures 11.579 Earth radii (1.03 Jupiter radii) and has a measured mass of 2129.45 Earth masses (6.7 Jupiter masses). Combining its mass and radius yields a mean bulk density of 7.56 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 15.88 g⊕ (155.73 m/s²), and an escape velocity of 151.7 km/s.
In its orbital architecture around Kepler-553, Kepler-553 c completes one full revolution every 328.24 Earth days at a semi-major axis of 0.898 AU (comparable to the inner terrestrial zone between Venus, Earth at 1.00 AU, and Mars at 1.52 AU). Its mean orbital velocity is approximately 29.8 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.346, swinging from 0.5873 AU at periapsis out to 1.2087 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 11.579 R⊕, Kepler-553 c exceeds the empirical ~1.8–2.2 R⊕ Fulton radius valley threshold, indicating a substantial hydrogen-helium or supercritical volatile envelope without a conventional solid terrestrial surface.
The host star Kepler-553 is classified as a stellar host with an effective photospheric temperature of 5,191 K, a radius of 0.902 R☉, a mass of 0.889 M☉, an estimated bolometric luminosity of 0.53 L☉. Stellar evolution modeling indicates an estimated stellar age of 8.8 Gyr and a metallicity of [Fe/H] = 0.152 dex (metal-rich relative to the Sun). From Earth, Kepler-553 shines at apparent V-band magnitude 15.034 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-553 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-553 c sharing its stellar neighborhood alongside Kepler-553 b.
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-553 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,191 K |
| Stellar Radius | 0.9020 R☉ |
| Stellar Mass | 0.8890 M☉ |
| Bolometric Luminosity | 0.53 L☉ |
| Metallicity [Fe/H] | 0.152 dex |
| Stellar Age | 8.800 Gyr |
| Apparent Magnitude | V: 15.034 · G: 14.957 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.898000 AU |
| Orbital Period | 328.24 days |
| Mean Orbital Velocity | 29.8 km/s |
| Orbital Eccentricity (e) | 0.34600 |
| Orbital Inclination (i) | 89.8314° |
| Mean Bulk Density | 7.56 g/cm³ (151.7 km/s vesc) |
| Insolation Flux | 0.5890 S⊕ (~802 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2376.100 LY (728.525 pc) |