Kepler-1038 b
Astrophysical Synthesis & Habitability Characterization
Kepler-1038 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-1038, located approximately 1905.2 light-years (584.14 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.152% across the stellar disk), this world measures 3.53 Earth radii (0.31 Jupiter radii) and has a measured mass of 12.2 Earth masses. Combining its mass and radius yields a mean bulk density of 1.53 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.98 g⊕ (9.61 m/s²), and an escape velocity of 20.8 km/s.
In its orbital architecture around Kepler-1038, Kepler-1038 b completes one full revolution every 148.46 Earth days at a semi-major axis of 0.5238 AU (situated at an orbital separation between Mercury's 0.39 AU and Venus's 0.72 AU). Its mean orbital velocity is approximately 38.4 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 3.530 R⊕, Kepler-1038 b 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-1038 is classified as a stellar host with an effective photospheric temperature of 5,335 K, a radius of 0.83 R☉, a mass of 0.87 M☉, an estimated bolometric luminosity of 0.501 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.27 Gyr and a metallicity of [Fe/H] = -0.04 dex (near-solar heavy-element abundance). From Earth, Kepler-1038 shines at apparent V-band magnitude 15.03 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-1038 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-1038 b sharing its stellar neighborhood alongside Kepler-1038 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-1038 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,335 K |
| Stellar Radius | 0.8300 R☉ |
| Stellar Mass | 0.8700 M☉ |
| Bolometric Luminosity | 0.501 L☉ |
| Metallicity [Fe/H] | -0.040 dex |
| Stellar Age | 4.270 Gyr |
| Apparent Magnitude | V: 15.030 · G: 14.856 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.523800 AU |
| Orbital Period | 148.46 days |
| Mean Orbital Velocity | 38.4 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.6600° |
| Mean Bulk Density | 1.53 g/cm³ (20.8 km/s vesc) |
| Insolation Flux | 1.5120 S⊕ (~2,058 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1905.200 LY (584.136 pc) |