DMPP-4 b
Astrophysical Synthesis & Habitability Characterization
DMPP-4 b is a confirmed sub-neptune exoplanet orbiting the star DMPP-4, located approximately 82.6 light-years (25.33 parsecs) from the Solar System. First announced in 2023 by Multiple Observatories using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), 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 DMPP-4, DMPP-4 b completes one full revolution every 3.498 Earth days at a semi-major axis of 0.04853 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 150.9 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.063 carries the world between 0.0455 AU at periapsis and 0.0516 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1646 K (+1373°C / +2503°F) and receiving 1,222.85 S⊕ (~1,664,294 W/m²), DMPP-4 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star DMPP-4 is classified as a warm F-type star of spectral type F5-F8 V with an effective photospheric temperature of 6,400 K, a radius of 1.38 R☉, a mass of 1.25 M☉, an estimated bolometric luminosity of 2.867 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.15 Gyr and a metallicity of [Fe/H] = -0.007 dex (near-solar heavy-element abundance). From Earth, DMPP-4 shines at apparent V-band magnitude 5.729 (visible to the unaided human eye under dark skies) 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 | DMPP-4 |
| Spectral Type | F5-F8 V |
| Effective Temp (Teff) | 6,400 K |
| Stellar Radius | 1.3800 R☉ |
| Stellar Mass | 1.2500 M☉ |
| Bolometric Luminosity | 2.867 L☉ |
| Metallicity [Fe/H] | -0.007 dex |
| Stellar Age | 2.150 Gyr |
| Apparent Magnitude | V: 5.729 · G: 5.600 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.048530 AU |
| Orbital Period | 3.498 days |
| Mean Orbital Velocity | 150.9 km/s |
| Orbital Eccentricity (e) | 0.06300 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.53 g/cm³ (20.8 km/s vesc) |
| Insolation Flux | 1222.8464 S⊕ (~1,664,294 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 82.600 LY (25.328 pc) |