Key parameters at a glance

A radius of 2.86 Earth radii
A mass of 15.60 Earth masses
Surface gravity around 1.91 g
An orbital period of 3.077 days
Semi-major axis 0.0227 AU
Equilibrium temperature 449 K (176 °C)
Distance from Earth 180.75 light-years
Earth Similarity Index 0.495
Travel time at Voyager 1 speed 3,187,568 years
Almost certainly tidally locked to its host star given the close orbit

TOI-2406 b Planet Profile

Physical Specs

Radius

2.86 R⊕

Radius (Jupiter)

0.255 R♃

Mass

15.60 M⊕

Mass (Jupiter)

0.049 M♃

Density

— g/cm³

Surface Gravity

1.91 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.495

HZ Position Inner

Controversial No

Discovery

Year 2021

Method Transit

Facility Transiting Exoplanet Survey Satellite (TESS)

Telescope 0.1 m TESS Telescope

Size rank in cohort

Rank by radius

#671of 1978

top 33.9%

This planet

2.86R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-58 c 2.86 R⊕ Kepler-142 c 2.86 R⊕ Kepler-170 c 2.86 R⊕

Metric	Earth	TOI-2406 b	Jupiter
Radius (R⊕)	1.00	2.86	11.21
Mass (M⊕)	1.00	15.60	317.83
Density (g/cm³)	5.51	—	1.33
Surface Gravity (g)	1.00	1.91	2.53
Insolation (S⊕)	1.00	6.69	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	15.600 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 212957629

Gaia DR2

Gaia DR2 2528453161326406016

Gaia DR3

Gaia DR3 2528453161326406016

System

TOI-2406

Percentile among Sub-Neptune cohort

Radius 2.860 R⊕ · percentile 66 / cohort 1978

Mass 15.600 M⊕ · percentile 93 / cohort 1978

Orbital period 3.08 d · percentile 5 / cohort 1946

Distance 55.42 pc · percentile 12 / cohort 1975

ESI 0.495 · percentile 70 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

3.077 days

Semi-major axis

0.0227 AU

Eccentricity

0.170

Inclination

89.80 °

Year Length

A year here lasts approximately 3.08 Earth days (0.8% of a terrestrial year) on a mildly elliptical path at a mean orbital distance of 0.0227 AU.

Transit Fingerprint

Depth

1.885 %

Duration

1.249 h

Impact parameter b

0.090

Rp / R★

0.128700

Transit midpoint (BJD)

2,459,115.9760

Photometric dip

Transit produces a flux drop of 18,849 ppm lasting ≈ 1.25 h.

Extended Orbital Architecture

Planet / star radius ratio

0.128700

Semi-major axis / stellar radius

23.950

Impact parameter (b)

0.090

RV semi-amplitude (K)

23.700 m/s

Transit mid-time (BJD)

2,459,115.9760

Long. of periastron (ω)

279.00°

Angular separation (arcsec)

0.40900

Eq. Temperature

449K

(176 °C)

Insolation (S⊕)

6.69

Earth = 1.00

Earth Similarity (ESI)

0.495

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — the surface is too hot to retain surface water. Close-orbiting tidally-locked around a cool host.

Discovery Paper

Primary reference

Wells et al. 2021

Instrument

TESS CCD Array

Publication

2021-09

Observation locale

Space

Discovery cohort

Planets confirmed in 2021 at Transiting Exoplanet Survey Satellite (TESS) (12 shown).

TOI-2257 b · Sub-Neptune TOI-2285 b · Super-Earth TOI-1231 b · Sub-Neptune AU Mic c · Sub-Neptune LHS 1678 c · Rocky Terrestrial LHS 1478 b · Rocky Terrestrial HD 207897 b · Sub-Neptune TOI-269 b · Sub-Neptune TIC 172900988 b · Gas Giant TOI-178 g · Sub-Neptune TOI-2076 d · Sub-Neptune TOI-1749 d · Sub-Neptune

Host System: TOI-2406

Spectral Class

M-type red dwarf

Effective Temperature

3,100 K — cooler than the Sun (5,778 K)

Estimated Age

—

Stellar Radius

0.204 R☉

Stellar Mass

0.166 M☉

Metallicity [Fe/H]

-0.26

Extended Stellar Properties

Surface gravity (log g)

5.041 dex

Stellar density

27.400 g/cm³

Systemic radial velocity

-29.50 km/s

Metallicity ratio

[Fe/H]

Distance

55.42 parsec

Light-years 180.75 ly

V-band magnitude

— mag

Voyager-speed travel 3,187,568 yr

Multi-band Host Photometry — 5 bands

Astrometric Data

Parallax

18.016 mas

Total Proper Motion

405.023 mas/yr

PM Right Ascension

225.75 mas/yr

PM Declination

-336.27 mas/yr

Galactic Cartesian (pc)

x = 0.987 · y = 0.153 · z = -0.059

Equatorial (J2000)

RA 8.80605° · Dec -3.37208°

Galactic ℓ, b

112.969° · -65.930°

Ecliptic λ, β

6.749° · -6.590°

HTM-20 index

-289013690