Key parameters at a glance

A radius of 2.91 Earth radii
A mass of 8.78 Earth masses
Surface gravity around 1.04 g
An orbital period of 4.579 days
Semi-major axis 0.0534 AU
Equilibrium temperature 1,210 K (937 °C)
Distance from Earth 546.63 light-years
Earth Similarity Index 0.191
Travel time at Voyager 1 speed 9,639,836 years

2 siblings around TOI-1117

TOI-1117 c 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
TOI-1117 b	Sub-Neptune	2.46	8.90	2.228	1,538	2025
TOI-1117 c this	Sub-Neptune	2.91	8.78	4.579	1,210	2025
TOI-1117 d	Sub-Neptune	3.27	10.71	8.665	978	2025

TOI-1117 c Planet Profile

Physical Specs

Radius

2.91 R⊕

Radius (Jupiter)

0.259 R♃

Mass

8.78 M⊕

Mass (Jupiter)

0.028 M♃

Density

1.96 g/cm³

Surface Gravity

1.04 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.191

HZ Position Inner

Controversial No

Discovery

Year 2025

Method Radial Velocity

Facility La Silla Observatory

Telescope 3.6 m ESO Telescope

Size rank in cohort

Rank by radius

#608of 1978

top 30.7%

This planet

2.91R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

TOI-1221 b 2.91 R⊕ HD 45184 c 2.91 R⊕ GJ 480 b 2.91 R⊕

Metric	Earth	TOI-1117 c	Jupiter
Radius (R⊕)	1.00	2.91	11.21
Mass (M⊕)	1.00	8.78	317.83
Density (g/cm³)	5.51	1.96	1.33
Surface Gravity (g)	1.00	1.04	2.53
Insolation (S⊕)	1.00	355.00	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Minimum mass (M sin i)	8.780 M⊕	Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

TIC

TIC 295541511

Gaia DR2

Gaia DR2 6436995652638923392

Gaia DR3

Gaia DR3 6436995652638923392

System

TOI-1117

Percentile among Sub-Neptune cohort

Radius 2.910 R⊕ · percentile 69 / cohort 1978

Mass 8.780 M⊕ · percentile 63 / cohort 1978

Orbital period 4.58 d · percentile 10 / cohort 1946

Distance 167.60 pc · percentile 27 / cohort 1975

ESI 0.191 · percentile 6 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

4.579 days

Semi-major axis

0.0534 AU

Eccentricity

0.000

Inclination

— °

Year Length

A year here lasts approximately 4.58 Earth days (1.3% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0534 AU.

Eq. Temperature

1,210K

(937 °C)

Insolation (S⊕)

355.00

Earth = 1.00

Earth Similarity (ESI)

0.191

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — the dayside is scorched.

Discovery Paper

Primary reference

Lockley et al. 2025

Instrument

HARPS Spectrograph

Publication

2025-06

Observation locale

Ground

Discovery cohort

Planets confirmed in 2025 at La Silla Observatory (12 shown).

Proxima Cen d · Rocky Terrestrial TOI-1203 c · Sub-Neptune HD 23079 c · Sub-Neptune HD 196067 c · Sub-Neptune HD 87816 b · Gas Giant HD 102888 b · Gas Giant HD 94890 c · Gas Giant TOI-756 c · Gas Giant TOI-1203 e · Neptune-like HD 94890 b · Gas Giant HD 87816 c · Gas Giant GJ 2126 b · Gas Giant

Host System: TOI-1117

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,635 K — cooler than the Sun (5,778 K)

Estimated Age

4.42 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

1.050 R☉

Stellar Mass

0.970 M☉

Metallicity [Fe/H]

0.14

Extended Stellar Properties

Surface gravity (log g)

4.410 dex

Stellar density

1.280 g/cm³

Rotational v·sin i

1.32 km/s

Rotation period

40.00 days

Activity index (log R'HK)

-5.030

Metallicity ratio

[Fe/H]

Distance

167.60 parsec

Light-years 546.63 ly

V-band magnitude

11.02 mag

Voyager-speed travel 9,639,836 yr

Multi-band Host Photometry — 11 bands

Astrometric Data

Parallax

5.938 mas

Total Proper Motion

41.569 mas/yr

PM Right Ascension

-15.32 mas/yr

PM Declination

-38.64 mas/yr

Galactic Cartesian (pc)

x = 0.025 · y = -0.399 · z = -0.917

Equatorial (J2000)

RA 273.60206° · Dec -66.41997°

Galactic ℓ, b

327.975° · -21.139°

Ecliptic λ, β

271.966° · -43.005°

HTM-20 index

842352940