Kepler-549 c
Astrophysical Synthesis & Habitability Characterization
Kepler-549 c is a confirmed sub-neptune exoplanet orbiting the star Kepler-549, located approximately 2071.6 light-years (635.15 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.1023% across the stellar disk), this world measures 2.93 Earth radii and has a measured mass of 8.91 Earth masses. Combining its mass and radius yields a mean bulk density of 1.95 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.04 g⊕ (10.2 m/s²), and an escape velocity of 19.5 km/s.
In its orbital architecture around Kepler-549, Kepler-549 c completes one full revolution every 117.04 Earth days at a semi-major axis of 0.45332 AU (situated at an orbital separation between Mercury's 0.39 AU and Venus's 0.72 AU). Its mean orbital velocity is approximately 42.1 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.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 2.930 R⊕, Kepler-549 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-549 is classified as a stellar host with an effective photospheric temperature of 5,360 K, a radius of 0.84 R☉, a mass of 0.88 M☉, an estimated bolometric luminosity of 0.523 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-549 shines at apparent V-band magnitude 14.805 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-549 system is a multi-planet architecture hosting 3 confirmed worlds, with Kepler-549 c sharing its stellar neighborhood alongside Kepler-549 d, Kepler-549 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-549 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,360 K |
| Stellar Radius | 0.8400 R☉ |
| Stellar Mass | 0.8800 M☉ |
| Bolometric Luminosity | 0.523 L☉ |
| Metallicity [Fe/H] | -0.030 dex |
| Stellar Age | 4.570 Gyr |
| Apparent Magnitude | V: 14.805 · G: 14.623 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.453320 AU |
| Orbital Period | 117.04 days |
| Mean Orbital Velocity | 42.1 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.9200° |
| Mean Bulk Density | 1.95 g/cm³ (19.5 km/s vesc) |
| Insolation Flux | 2.5100 S⊕ (~3,416 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2071.600 LY (635.145 pc) |