Kepler-1990 b
Astrophysical Synthesis & Habitability Characterization
Kepler-1990 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-1990, located approximately 1280.9 light-years (392.74 parsecs) from the Solar System. First announced in 2023 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0784% across the stellar disk), this world measures 3.27 Earth radii (0.29 Jupiter radii) and has a measured mass of 10.7 Earth masses. Combining its mass and radius yields a mean bulk density of 1.69 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1 g⊕ (9.81 m/s²), and an escape velocity of 20.2 km/s.
In its orbital architecture around Kepler-1990, Kepler-1990 b completes one full revolution every 1.735 Earth days at a semi-major axis of 0.0286 AU (an ultra-close orbit less than one-seventh of Mercury's 0.387 AU distance from the Sun, where strong stellar tidal forces typically induce synchronous rotation). Its mean orbital velocity is approximately 179.3 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 1554 K (+1281°C / +2338°F) and receiving 1,372.87 S⊕ (~1,868,476 W/m²), Kepler-1990 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-1990 is classified as a stellar host with an effective photospheric temperature of 5,751 K, a radius of 1.071 R☉, a mass of 1.028 M☉, an estimated bolometric luminosity of 1.126 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.5 Gyr and a metallicity of [Fe/H] = 0.21 dex (metal-rich relative to the Sun). From Earth, Kepler-1990 shines at apparent V-band magnitude 11.946 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-1990 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-1990 b sharing its stellar neighborhood alongside Kepler-1990 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-1990 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,751 K |
| Stellar Radius | 1.0710 R☉ |
| Stellar Mass | 1.0280 M☉ |
| Bolometric Luminosity | 1.126 L☉ |
| Metallicity [Fe/H] | 0.210 dex |
| Stellar Age | 2.500 Gyr |
| Apparent Magnitude | V: 11.946 · G: 12.583 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.028600 AU |
| Orbital Period | 1.735 days |
| Mean Orbital Velocity | 179.3 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.5700° |
| Mean Bulk Density | 1.69 g/cm³ (20.2 km/s vesc) |
| Insolation Flux | 1372.8700 S⊕ (~1,868,476 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1280.900 LY (392.739 pc) |