Key parameters at a glance

A radius of 2.08 Earth radii
A mass of 6.57 Earth masses
Surface gravity around 1.52 g
An orbital period of 13.176 days
Semi-major axis 0.0809 AU
Equilibrium temperature 368 K (95 °C)
Distance from Earth 101.30 light-years
Earth Similarity Index 0.710
Travel time at Voyager 1 speed 1,786,480 years
Almost certainly tidally locked to its host star given the close orbit

1 sibling around TOI-406

TOI-406.01 shares its host star with 1 other confirmed planet. Side-by-side measurements below.

Planet	Type	Radius (R⊕)	Mass (M⊕)	Period (d)	Eq. T (K)	Year
TOI-406 c	Super-Earth	1.32	2.08	3.307	584	2024
TOI-406.01 this	Sub-Neptune	2.08	6.57	13.176	368	2024

TOI-406.01 Planet Profile

Physical Specs

Radius

2.08 R⊕

Radius (Jupiter)

0.186 R♃

Mass

6.57 M⊕

Mass (Jupiter)

0.021 M♃

Density

4.10 g/cm³

Surface Gravity

1.52 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.710

HZ Position Inner

Controversial No

Discovery

Year 2024

Method Transit

Facility Transiting Exoplanet Survey Satellite (TESS)

Telescope 0.1 m TESS Telescope

Size rank in cohort

Rank by radius

#1846of 1978

top 93.3%

This planet

2.08R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-1195 b 2.08 R⊕ Kepler-405 b 2.08 R⊕ Kepler-237 c 2.08 R⊕

Metric	Earth	TOI-406.01	Jupiter
Radius (R⊕)	1.00	2.08	11.21
Mass (M⊕)	1.00	6.57	317.83
Density (g/cm³)	5.51	4.10	1.33
Surface Gravity (g)	1.00	1.52	2.53
Insolation (S⊕)	1.00	3.00	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	6.570 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 153065527

Gaia DR2

Gaia DR2 4851053999056603904

Gaia DR3

Gaia DR3 4851053999056603904

System

TOI-406

Percentile among Sub-Neptune cohort

Radius 2.080 R⊕ · percentile 6 / cohort 1978

Mass 6.570 M⊕ · percentile 34 / cohort 1978

Orbital period 13.18 d · percentile 45 / cohort 1946

Distance 31.06 pc · percentile 8 / cohort 1975

ESI 0.710 · percentile 93 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

13.176 days

Semi-major axis

0.0809 AU

Eccentricity

0.056

Inclination

89.40 °

Year Length

A year here lasts approximately 13.18 Earth days (3.6% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0809 AU.

Transit Fingerprint

Depth

0.248 %

Duration

2.170 h

Impact parameter b

0.430

Rp / R★

0.046600

Transit midpoint (BJD)

2,458,388.5700

Photometric dip

Transit produces a flux drop of 2,479 ppm lasting ≈ 2.17 h.

Extended Orbital Architecture

Planet / star radius ratio

0.046600

Semi-major axis / stellar radius

44.600

Impact parameter (b)

0.430

RV semi-amplitude (K)

3.250 m/s

Transit mid-time (BJD)

2,458,388.5700

Long. of periastron (ω)

169.00°

Angular separation (arcsec)

2.60000

Eq. Temperature

368K

(95 °C)

Insolation (S⊕)

3.00

Earth = 1.00

Earth Similarity (ESI)

0.710

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — liquid water is physically possible with adequate atmospheric pressure. Close-orbiting tidally-locked around a cool host.

Detection Signatures

Transit photometry

A transit dip has been observed from at least one telescope.

Radial velocity

Stellar wobble has been measured spectroscopically.

Discovery Paper

Primary reference

Hord et al. 2024

Instrument

TESS CCD Array

Publication

2024-05

Observation locale

Space

Discovery cohort

Planets confirmed in 2024 at Transiting Exoplanet Survey Satellite (TESS) (12 shown).

Gliese 12 b · Rocky Terrestrial TOI-6002 b · Super-Earth TOI-5713 b · Super-Earth TOI-4336 A b · Sub-Neptune TOI-1224 c · Sub-Neptune LHS 1678 d · Rocky Terrestrial TOI-2088 b · Sub-Neptune TOI-2120 b · Sub-Neptune TOI-1806.01 · Sub-Neptune TOI-4633 c · Sub-Neptune TOI-260 b · Super-Earth TOI-663 d · Super-Earth

Host System: TOI-406

Spectral Class

M-type red dwarf

Effective Temperature

3,392 K — cooler than the Sun (5,778 K)

Estimated Age

—

Stellar Radius

0.410 R☉

Stellar Mass

0.408 M☉

Metallicity [Fe/H]

-0.02

Extended Stellar Properties

Surface gravity (log g)

4.690 dex

Stellar density

9.446 g/cm³

Systemic radial velocity

14.48 km/s

Rotation period

29.20 days

Activity index (log R'HK)

-5.167

Metallicity ratio

[M/H]

Distance

31.06 parsec

Light-years 101.30 ly

V-band magnitude

13.77 mag

Voyager-speed travel 1,786,480 yr

Multi-band Host Photometry — 7 bands

Astrometric Data

Parallax

32.167 mas

Total Proper Motion

414.925 mas/yr

PM Right Ascension

41.67 mas/yr

PM Declination

-412.83 mas/yr

Galactic Cartesian (pc)

x = 0.483 · y = 0.561 · z = -0.672

Equatorial (J2000)

RA 49.26264° · Dec -42.24415°

Galactic ℓ, b

249.563° · -56.807°

Ecliptic λ, β

27.096° · -57.133°

HTM-20 index

-938313135