Key parameters at a glance

A radius of 2.01 Earth radii
A mass of 4.70 Earth masses
Surface gravity around 1.16 g
An orbital period of 12.921 days
Semi-major axis 0.0619 AU
Equilibrium temperature 249 K (-24 °C)
Distance from Earth 115.51 light-years
Earth Similarity Index 0.750
Travel time at Voyager 1 speed 2,037,003 years
Almost certainly tidally locked to its host star given the close orbit

TOI-7166 b Planet Profile

Physical Specs

Radius

2.01 R⊕

Radius (Jupiter)

0.179 R♃

Mass

4.70 M⊕

Mass (Jupiter)

0.015 M♃

Density

3.18 g/cm³

Surface Gravity

1.16 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.750

HZ Position Habitable

Controversial No

Discovery

Year 2025

Method Transit

Facility Transiting Exoplanet Survey Satellite (TESS)

Telescope 0.1 m TESS Telescope

Size rank in cohort

Rank by radius

#1940of 1978

top 98.0%

This planet

2.01R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-415 c 2.01 R⊕ Kepler-260 b 2.01 R⊕ Kepler-280 c 2.01 R⊕

Metric	Earth	TOI-7166 b	Jupiter
Radius (R⊕)	1.00	2.01	11.21
Mass (M⊕)	1.00	4.70	317.83
Density (g/cm³)	5.51	3.18	1.33
Surface Gravity (g)	1.00	1.16	2.53
Insolation (S⊕)	1.00	1.07	0.037

Star Catalogue Identifiers

TIC

TIC 288421619

Gaia DR2

Gaia DR2 1740534092250753920

Gaia DR3

Gaia DR3 1740534092250753920

System

TOI-7166

Percentile among Sub-Neptune cohort

Radius 2.010 R⊕ · percentile 1 / cohort 1978

Mass 4.700 M⊕ · percentile 3 / cohort 1978

Orbital period 12.92 d · percentile 44 / cohort 1946

Distance 35.42 pc · percentile 9 / cohort 1975

ESI 0.750 · percentile 97 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

12.921 days

Semi-major axis

0.0619 AU

Eccentricity

0.000

Inclination

89.80 °

Year Length

A year here lasts approximately 12.92 Earth days (3.5% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0619 AU.

Transit Fingerprint

Depth

0.678 %

Duration

1.750 h

Impact parameter b

0.200

Rp / R★

0.082300

Transit midpoint (BJD)

2,460,847.7428

Photometric dip

Transit produces a flux drop of 6,776 ppm lasting ≈ 1.75 h.

Extended Orbital Architecture

Planet / star radius ratio

0.082300

Semi-major axis / stellar radius

59.980

Impact parameter (b)

0.200

Transit mid-time (BJD)

2,460,847.7428

Angular separation (arcsec)

1.75000

Eq. Temperature

249K

(-24 °C)

Insolation (S⊕)

1.07

Earth = 1.00

Earth Similarity (ESI)

0.750

0 = alien, 1 = Earth-identical

Within the conservative habitable zone — surface water would be frozen. Close-orbiting tidally-locked around a cool host.

Discovery Paper

Primary reference

Barkaoui et al. 2025

Instrument

TESS CCD Array

Publication

2025-12

Observation locale

Space

Discovery cohort

Planets confirmed in 2025 at Transiting Exoplanet Survey Satellite (TESS) (12 shown).

TOI-1266 d · Super-Earth TOI-2267 c · Rocky Terrestrial TOI-5799 c · Super-Earth TOI-5728 b · Super-Earth TOI-5716 b · Rocky Terrestrial TOI-2267 b · Rocky Terrestrial TOI-2093 c · Sub-Neptune TOI-2267 d · Super-Earth TOI-5489 c · Super-Earth TOI-1743 b · Super-Earth TOI-4364 b · Sub-Neptune HD 35843 c · Sub-Neptune

Host System: TOI-7166

Spectral Class

M-type red dwarf

Effective Temperature

3,099 K — cooler than the Sun (5,778 K)

Estimated Age

4.00 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

0.222 R☉

Stellar Mass

0.190 M☉

Metallicity [Fe/H]

-0.20

Extended Stellar Properties

Surface gravity (log g)

5.020 dex

Stellar density

24.475 g/cm³

Systemic radial velocity

-50.14 km/s

Metallicity ratio

[Fe/H]

Distance

35.42 parsec

Light-years 115.51 ly

V-band magnitude

15.79 mag

Voyager-speed travel 2,037,003 yr

Multi-band Host Photometry — 6 bands

Astrometric Data

Parallax

28.208 mas

Total Proper Motion

375.684 mas/yr

PM Right Ascension

260.60 mas/yr

PM Declination

-270.60 mas/yr

Galactic Cartesian (pc)

x = 0.764 · y = -0.626 · z = 0.155

Equatorial (J2000)

RA 320.68064° · Dec 8.88940°

Galactic ℓ, b

60.864° · -27.951°

Ecliptic λ, β

326.133° · 23.004°

HTM-20 index

-1857496442