Confirmed Exoplanet Discovered 2026

TOI-5789 e

A sub-neptune orbiting the k-type orange TOI-5789, located approximately 66.7 light-years from Earth.

Key parameters at a glance

  • A radius of 3.43 Earth radii
  • A mass of 11.61 Earth masses
  • Surface gravity around 0.99 g
  • An orbital period of 62.980 days
  • Semi-major axis 0.2901 AU
  • Equilibrium temperature 424 K (151 °C)
  • Distance from Earth 66.73 light-years
  • Earth Similarity Index 0.503
  • Travel time at Voyager 1 speed 1,176,701 years

3 siblings around TOI-5789

TOI-5789 e shares its host star with 3 other confirmed planets. Side-by-side measurements below.

Planet Type Radius (R⊕) Mass (M⊕) Period (d) Eq. T (K) Year
TOI-5789 b Super-Earth 1.26 2.12 2.764 1,201 2026
TOI-5789 c Sub-Neptune 2.86 5.00 12.928 718
TOI-5789 d Super-Earth 1.91 4.29 29.650 545 2026
TOI-5789 e this Sub-Neptune 3.43 11.61 62.980 424 2026

TOI-5789 e Planet Profile

Physical Specs

Radius
3.43 R⊕
Radius (Jupiter)
0.306 R♃
Mass
11.61 M⊕
Mass (Jupiter)
0.037 M♃
Density
1.58 g/cm³
Surface Gravity
0.99 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.503
HZ Position Unknown
Controversial No

Discovery

Year 2026
Method Radial Velocity
Facility Multiple Observatories
Telescope Multiple Telescopes

Size rank in cohort

Rank by radius

#205of 1978

top 10.3%

This planet

3.43R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Metric Earth TOI-5789 e Jupiter
Radius (R⊕)1.003.4311.21
Mass (M⊕)1.0011.61317.83
Density (g/cm³)5.511.581.33
Surface Gravity (g)1.000.992.53
Insolation (S⊕)1.000.037

Alternative Mass Estimates

Method Value Interpretation
Minimum mass (M sin i) 11.610 M⊕ Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

HD

HD 191785

HIP

HIP 99452

TIC

TIC 87216634

Gaia DR2

Gaia DR2 1809360187271699584

System

TOI-5789

Percentile among Sub-Neptune cohort

Radius 3.430 R⊕ · percentile 89 / cohort 1978
Mass 11.610 M⊕ · percentile 83 / cohort 1978
Orbital period 62.98 d · percentile 90 / cohort 1946
Distance 20.46 pc · percentile 4 / cohort 1975
ESI 0.503 · percentile 71 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period
62.980 days
Semi-major axis
0.2901 AU
Eccentricity
0.071
Inclination
°

Year Length

A year here lasts approximately 62.98 Earth days (17.2% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.2901 AU.

Eq. Temperature

424K

(151 °C)

Insolation (S⊕)

Earth = 1.00

Earth Similarity (ESI)

0.503

0 = alien, 1 = Earth-identical

Insufficient insolation data — the surface is too hot to retain surface water.

Discovery Paper

Primary reference

Bonomo et al. 2025

Instrument

Multiple Instruments

Publication

2025-10

Observation locale

Ground

Host System: TOI-5789

Spectral Class

K-type orange

Effective Temperature

5,185 K — cooler than the Sun (5,778 K)

Estimated Age

9.40 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

0.833 R☉

Stellar Mass

0.821 M☉

Metallicity [Fe/H]

-0.12

Extended Stellar Properties

Surface gravity (log g)

4.511 dex

Stellar density

2.000 g/cm³

Systemic radial velocity

-49.32 km/s

Rotational v·sin i

1.20 km/s

Activity index (log R'HK)

-5.153

Metallicity ratio

[Fe/H]

Distance
20.46 parsec
Light-years 66.73 ly
V-band magnitude
7.35 mag
Voyager-speed travel 1,176,701 yr

Multi-band Host Photometry — 7 bands

5.48.28.16B7.35V7.10Gaia6.57TESS5.83J5.42H5.35K

Astrometric Data

Parallax

48.852 mas

Total Proper Motion

575.094 mas/yr

PM Right Ascension

-414.66 mas/yr

PM Declination

398.48 mas/yr

Galactic Cartesian (pc)

x = 0.520 · y = -0.807 · z = 0.279

Equatorial (J2000)

RA 302.77345° · Dec 16.18971°

Galactic ℓ, b

56.682° · -9.438°

Ecliptic λ, β

309.527° · 35.240°

HTM-20 index

1705062875

Observation Record

Photometric series

1

Stellar spectra

3

Archive notes

1

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