HD 238090 b
Astrophysical Synthesis & Habitability Characterization
HD 238090 b is a confirmed sub-neptune exoplanet orbiting the star HD 238090, located approximately 49.7 light-years (15.24 parsecs) from the Solar System. First announced in 2020 by Multiple Observatories using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 2.52 Earth radii and has a measured mass of 6.89 Earth masses. Combining its mass and radius yields a mean bulk density of 2.37 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.08 g⊕ (10.59 m/s²), and an escape velocity of 18.5 km/s.
In its orbital architecture around HD 238090, HD 238090 b completes one full revolution every 13.671 Earth days at a semi-major axis of 0.0932 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 74.2 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.3, swinging from 0.0652 AU at periapsis out to 0.1212 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 470 K (+197°C / +387°F) and receiving 8.10 S⊕ (~11,024 W/m²), HD 238090 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 238090 is classified as a low-mass red dwarf of spectral type M0.0 V with an effective photospheric temperature of 3,933 K, a radius of 0.57 R☉, a mass of 0.578 M☉, an estimated bolometric luminosity of 0.07 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.03 dex (near-solar heavy-element abundance). From Earth, HD 238090 shines at apparent V-band magnitude 9.71 (accessible to binoculars and small amateur telescopes) 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: Multiple Observatories · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 238090 |
| Spectral Type | M0.0 V |
| Effective Temp (Teff) | 3,933 K |
| Stellar Radius | 0.5700 R☉ |
| Stellar Mass | 0.5780 M☉ |
| Bolometric Luminosity | 0.07 L☉ |
| Metallicity [Fe/H] | -0.030 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 9.710 · G: 9.038 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.093200 AU |
| Orbital Period | 13.671 days |
| Mean Orbital Velocity | 74.2 km/s |
| Orbital Eccentricity (e) | 0.30000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 2.37 g/cm³ (18.5 km/s vesc) |
| Insolation Flux | 8.1000 S⊕ (~11,024 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 49.700 LY (15.235 pc) |