Key parameters at a glance

A radius of 13.56 Earth radii
A mass of 129.99 Earth masses
Surface gravity around 0.71 g
An orbital period of 3.051 days
Semi-major axis 0.0448 AU
Equilibrium temperature 1,381 K (1108 °C)
Distance from Earth 3,575.29 light-years
Earth Similarity Index 0.081
Travel time at Voyager 1 speed 63,050,226 years

NGTS-18 b Planet Profile

Physical Specs

Radius

13.56 R⊕

Radius (Jupiter)

1.210 R♃

Mass

129.99 M⊕

Mass (Jupiter)

0.409 M♃

Density

0.28 g/cm³

Surface Gravity

0.71 g (Earth)

Classification

Planet Type

Gas Giant

ESI Score 0.081

HZ Position Inner

Controversial No

Discovery

Year 2021

Method Transit

Facility Next-Generation Transit Survey (NGTS)

Telescope 20 cm NGTS telescope

Size rank in cohort

Rank by radius

#664of 1771

top 37.4%

This planet

13.56R⊕

Gas Giant median

13.52R⊕

Nearest-size peers

K2-140 b 13.56 R⊕ HAT-P-5 b 13.56 R⊕ WASP-26 b 13.56 R⊕

Metric	Earth	NGTS-18 b	Jupiter
Radius (R⊕)	1.00	13.56	11.21
Mass (M⊕)	1.00	129.99	317.83
Density (g/cm³)	5.51	0.28	1.33
Surface Gravity (g)	1.00	0.71	2.53
Insolation (S⊕)	1.00	845.00	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	129.992 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 142211778

Gaia DR2

Gaia DR2 3462511310147530752

Gaia DR3

Gaia DR3 3462511310147530752

System

NGTS-18

Percentile among Gas Giant cohort

Radius 13.563 R⊕ · percentile 62 / cohort 1771

Mass 129.992 M⊕ · percentile 9 / cohort 1747

Orbital period 3.05 d · percentile 16 / cohort 1533

Distance 1,096.19 pc · percentile 87 / cohort 1759

ESI 0.081 · percentile 19 / cohort 1771

Orbit & Habitability

Orbital Dynamics

Period

3.051 days

Semi-major axis

0.0448 AU

Eccentricity

0.000

Inclination

— °

Year Length

A year here lasts approximately 3.05 Earth days (0.8% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0448 AU.

Transit Fingerprint

Depth

0.940 %

Duration

3.601 h

Impact parameter b

0.183

Rp / R★

0.089000

Transit midpoint (BJD)

2,458,564.4506

Photometric dip

Transit produces a flux drop of 9,403 ppm lasting ≈ 3.60 h.

Extended Orbital Architecture

Planet / star radius ratio

0.089000

Semi-major axis / stellar radius

6.970

Impact parameter (b)

0.183

RV semi-amplitude (K)

62.000 m/s

Transit mid-time (BJD)

2,458,564.4506

Angular separation (arcsec)

0.04090

Eq. Temperature

1,381K

(1108 °C)

Insolation (S⊕)

845.00

Earth = 1.00

Earth Similarity (ESI)

0.081

0 = alien, 1 = Earth-identical

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

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

Tilbrook et al. 2021

Instrument

NGTS CCD array

Publication

2021-03

Observation locale

Ground

Discovery cohort

Planets confirmed in 2021 at Next-Generation Transit Survey (NGTS) (5 shown).

NGTS-14 A b · Neptune-like NGTS-15 b · Gas Giant NGTS-13 b · Gas Giant NGTS-16 b · Gas Giant NGTS-17 b · Gas Giant

Host System: NGTS-18

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,610 K — cooler than the Sun (5,778 K)

Estimated Age

10.84 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

1.392 R☉

Stellar Mass

1.003 M☉

Metallicity [Fe/H]

0.15

Extended Stellar Properties

Surface gravity (log g)

4.160 dex

Stellar density

0.539 g/cm³

Systemic radial velocity

5.19 km/s

Rotational v·sin i

0.50 km/s

Metallicity ratio

[Fe/H]

Distance

1,096.19 parsec

Light-years 3,575.29 ly

V-band magnitude

14.59 mag

Voyager-speed travel 63,050,226 yr

Multi-band Host Photometry — 11 bands

Astrometric Data

Parallax

0.884 mas

Total Proper Motion

2.837 mas/yr

PM Right Ascension

-2.42 mas/yr

PM Declination

1.49 mas/yr

Galactic Cartesian (pc)

x = -0.814 · y = -0.008 · z = -0.581

Equatorial (J2000)

RA 180.54622° · Dec -35.54861°

Galactic ℓ, b

291.777° · 26.254°

Ecliptic λ, β

196.327° · -32.028°

HTM-20 index

474574292