Key parameters at a glance

A radius of 1.02 Earth radii
A mass of 1.05 Earth masses
Surface gravity around 1.01 g
An orbital period of 12.736 days
Distance from Earth 31.71 light-years
Earth Similarity Index 0.994
Travel time at Voyager 1 speed 559,192 years
Almost certainly tidally locked to its host star given the close orbit

2 siblings around AU Mic

AU Mic d shares its host star with 2 other confirmed planets. Side-by-side measurements below.

Planet	Type	Radius (R⊕)	Mass (M⊕)	Period (d)	Eq. T (K)	Year
AU Mic b	Neptune-like	4.79	8.99	8.463	555	2020
AU Mic d this	Rocky Terrestrial	1.02	1.05	12.736	—	2023
AU Mic c	Sub-Neptune	2.79	14.46	18.859	425	2021

AU Mic d Planet Profile

Physical Specs

Radius

1.02 R⊕

Radius (Jupiter)

0.091 R♃

Mass

1.05 M⊕

Mass (Jupiter)

0.003 M♃

Density

5.45 g/cm³

Surface Gravity

1.01 g (Earth)

Classification

Planet Type

Rocky Terrestrial

ESI Score 0.994

HZ Position Unknown

Controversial No

Discovery

Year 2023

Method Transit Timing Variations

Facility Multiple Observatories

Telescope Multiple Telescopes

Size rank in cohort

Rank by radius

#311of 570

top 54.4%

This planet

1.02R⊕

Rocky Terrestrial median

1.01R⊕

Nearest-size peers

Kepler-336 b 1.02 R⊕ Kepler-130 b 1.02 R⊕ Proxima Cen b 1.02 R⊕

Metric	Earth	AU Mic d	Jupiter
Radius (R⊕)	1.00	1.02	11.21
Mass (M⊕)	1.00	1.05	317.83
Density (g/cm³)	5.51	5.45	1.33
Surface Gravity (g)	1.00	1.01	2.53
Insolation (S⊕)	1.00	—	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	1.053 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

HD 197481

HIP

HIP 102409

TIC

TIC 441420236

Gaia DR2

Gaia DR2 6794047652729201024

Gaia DR3

Gaia DR3 6794047652729201024

System

AU Mic

Percentile among Rocky Terrestrial cohort

Radius 1.020 R⊕ · percentile 44 / cohort 570

Mass 1.053 M⊕ · percentile 40 / cohort 570

Orbital period 12.74 d · percentile 84 / cohort 567

Distance 9.72 pc · percentile 5 / cohort 566

ESI 0.994 · percentile 99 / cohort 570

Orbit & Habitability

Orbital Dynamics

Period

12.736 days

Semi-major axis

— AU

Eccentricity

0.003

Inclination

89.32 °

Year Length

A year here lasts approximately 12.74 Earth days (3.5% of a terrestrial year) on a nearly circular orbit.

Eq. Temperature

—

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.994

0 = alien, 1 = Earth-identical

Insufficient insolation data. Close-orbiting tidally-locked around a cool host.

Discovery Paper

Primary reference

Wittrock et al. 2023

Instrument

Multiple Instruments

Publication

2023-12

Observation locale

Ground

Discovery cohort

Planets confirmed in 2023 at Multiple Observatories (12 shown).

DMPP-4 b · Sub-Neptune HD 110067 g · Sub-Neptune GJ 806 c · Sub-Neptune HD 110067 f · Sub-Neptune HD 110067 e · Super-Earth TIC 279401253 c · Gas Giant HD 112570 b · Gas Giant HD 110067 d · Sub-Neptune HD 154391 b · Gas Giant HAT-P-2 c · Gas Giant HD 110067 b · Sub-Neptune HD 110067 c · Sub-Neptune

Host System: AU Mic

Spectral Class

M-type red dwarf

Effective Temperature

3,678 K — cooler than the Sun (5,778 K)

Estimated Age

0.02 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

0.744 R☉

Stellar Mass

0.510 M☉

Metallicity [Fe/H]

0.23

Extended Stellar Properties

Surface gravity (log g)

4.404 dex

Stellar density

1.750 g/cm³

Systemic radial velocity

-6.31 km/s

Rotational v·sin i

8.50 km/s

Rotation period

4.84 days

Metallicity ratio

[Fe/H]

Distance

9.72 parsec

Light-years 31.71 ly

V-band magnitude

8.81 mag

Voyager-speed travel 559,192 yr

Multi-band Host Photometry — 12 bands

Astrometric Data

Parallax

102.829 mas

Total Proper Motion

456.863 mas/yr

PM Right Ascension

281.42 mas/yr

PM Declination

-359.90 mas/yr

Galactic Cartesian (pc)

x = 0.564 · y = -0.642 · z = -0.520

Equatorial (J2000)

RA 311.29114° · Dec -31.34245°

Galactic ℓ, b

12.653° · -36.804°

Ecliptic λ, β

305.307° · -12.825°

HTM-20 index

1266543779

Observation Record

Photometric series

Stellar spectra

Archive notes