Confirmed Exoplanet Discovered 2026

TOI-5788 c

A sub-neptune orbiting the g-type yellow (sun-like) TOI-5788, located approximately 318.4 light-years from Earth.

Key parameters at a glance

  • A radius of 2.27 Earth radii
  • A mass of 6.40 Earth masses
  • Surface gravity around 1.24 g
  • An orbital period of 16.213 days
  • Semi-major axis 0.1197 AU
  • Equilibrium temperature 667 K (394 °C)
  • Distance from Earth 318.37 light-years
  • Earth Similarity Index 0.399
  • Travel time at Voyager 1 speed 5,614,524 years

1 sibling around TOI-5788

TOI-5788 c 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-5788 b Super-Earth 1.53 3.72 6.341 910 2026
TOI-5788 c this Sub-Neptune 2.27 6.40 16.213 667 2026

TOI-5788 c Planet Profile

Physical Specs

Radius
2.27 R⊕
Radius (Jupiter)
0.203 R♃
Mass
6.40 M⊕
Mass (Jupiter)
0.020 M♃
Density
3.03 g/cm³
Surface Gravity
1.24 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.399
HZ Position Inner
Controversial No

Discovery

Year 2026
Method Transit
Facility Transiting Exoplanet Survey Satellite (TESS)
Telescope 0.1 m TESS Telescope

Size rank in cohort

Rank by radius

#1553of 1978

top 78.5%

This planet

2.27R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Metric Earth TOI-5788 c Jupiter
Radius (R⊕)1.002.2711.21
Mass (M⊕)1.006.40317.83
Density (g/cm³)5.513.031.33
Surface Gravity (g)1.001.242.53
Insolation (S⊕)1.0049.800.037

Alternative Mass Estimates

Method Value Interpretation
Best measured mass 6.400 M⊕ Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 42883782

Gaia DR2

Gaia DR2 2042653052618584960

Gaia DR3

Gaia DR3 2042653052618584960

System

TOI-5788

Percentile among Sub-Neptune cohort

Radius 2.272 R⊕ · percentile 21 / cohort 1978
Mass 6.400 M⊕ · percentile 32 / cohort 1978
Orbital period 16.21 d · percentile 54 / cohort 1946
Distance 97.61 pc · percentile 19 / cohort 1975
ESI 0.399 · percentile 52 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period
16.213 days
Semi-major axis
0.1197 AU
Eccentricity
0.046
Inclination
89.60 °

Year Length

A year here lasts approximately 16.21 Earth days (4.4% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.1197 AU.

Transit Fingerprint

Depth

0.053 %

Duration

3.551 h

Rp / R★

0.023940

Transit midpoint (BJD)

2,459,608.5914

Photometric dip

Transit produces a flux drop of 530 ppm lasting ≈ 3.55 h.

Extended Orbital Architecture

Planet / star radius ratio

0.023940

RV semi-amplitude (K)

1.780 m/s

Transit mid-time (BJD)

2,459,608.5914

Long. of periastron (ω)

148.00°

Angular separation (arcsec)

1.23000

Eq. Temperature

667K

(394 °C)

Insolation (S⊕)

49.80

Earth = 1.00

Earth Similarity (ESI)

0.399

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — the surface is too hot to retain surface water.

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

Lakeland et al. 2026

Instrument

TESS CCD Array

Publication

2026-01

Observation locale

Space

Host System: TOI-5788

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,615 K — cooler than the Sun (5,778 K)

Estimated Age

5.72 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

0.870 R☉

Stellar Mass

0.870 M☉

Metallicity [Fe/H]

-0.32

Extended Stellar Properties

Surface gravity (log g)

4.420 dex

Stellar density

1.889 g/cm³

Systemic radial velocity

-59.36 km/s

Rotational v·sin i

2.00 km/s

Activity index (log R'HK)

-4.940

Metallicity ratio

[Fe/H]

Distance
97.61 parsec
Light-years 318.37 ly
V-band magnitude
10.15 mag
Voyager-speed travel 5,614,524 yr

Multi-band Host Photometry — 11 bands

8.310.810.83B10.15V10.06Gaia9.61TESS8.95J8.66H8.58K8.55W18.59W28.53W38.28W4

Astrometric Data

Parallax

10.216 mas

Total Proper Motion

120.921 mas/yr

PM Right Ascension

17.20 mas/yr

PM Declination

119.69 mas/yr

Galactic Cartesian (pc)

x = 0.255 · y = -0.811 · z = 0.526

Equatorial (J2000)

RA 287.42490° · Dec 31.76153°

Galactic ℓ, b

63.437° · 10.358°

Ecliptic λ, β

295.450° · 53.672°

HTM-20 index

-625989599

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