AU Mic d
Astrophysical Synthesis & Habitability Characterization
AU Mic d is a confirmed terrestrial exoplanet orbiting the star AU Mic, located approximately 31.7 light-years (9.72 parsecs) from the Solar System. First announced in 2023 by Multiple Observatories using the Transit Timing Variations detection technique (producing an estimated primary transit depth of 0.0158% across the stellar disk), this world measures 1.02 Earth radii and has a measured mass of 1.053 Earth masses. Combining its mass and radius yields a mean bulk density of 5.47 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 1.01 g⊕ (9.9 m/s²), and an escape velocity of 11.4 km/s.
In its orbital architecture around AU Mic, AU Mic d completes one full revolution every 12.736 Earth days. With a near-circular eccentricity of e = 0.00305, the planet experiences minimal orbital distance variation.
ℹ️ Thermal & Atmospheric Regime: Current photometric and spectroscopic constraints for AU Mic d place it outside the conservative habitable zone definition pending further atmospheric characterization.
The host star AU Mic is classified as a low-mass red dwarf of spectral type M1 V with an effective photospheric temperature of 3,678 K, a radius of 0.744 R☉, a mass of 0.51 M☉, an estimated bolometric luminosity of 0.091 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.02 Gyr and a metallicity of [Fe/H] = 0.23 dex (metal-rich relative to the Sun). From Earth, AU Mic shines at apparent V-band magnitude 8.81 (accessible to binoculars and small amateur telescopes) in the Southern celestial hemisphere. The AU Mic system is a multi-planet architecture hosting 4 confirmed worlds, with AU Mic d sharing its stellar neighborhood alongside AU Mic b, AU Mic c, AU Mic e.
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 | AU Mic |
| Spectral Type | M1 V |
| Effective Temp (Teff) | 3,678 K |
| Stellar Radius | 0.7440 R☉ |
| Stellar Mass | 0.5100 M☉ |
| Bolometric Luminosity | 0.091 L☉ |
| Metallicity [Fe/H] | 0.230 dex |
| Stellar Age | 0.020 Gyr |
| Apparent Magnitude | V: 8.810 · G: 7.840 |
| System Architecture | 1 Star, 4 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | — |
| Orbital Period | 12.736 days |
| Orbital Eccentricity (e) | 0.00305 |
| Orbital Inclination (i) | 89.3181° |
| Mean Bulk Density | 5.47 g/cm³ (11.4 km/s vesc) |
| Insolation Flux | — |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 31.700 LY (9.722 pc) |