Key parameters at a glance

A radius of 17.88 Earth radii
A mass of 235.19 Earth masses
Surface gravity around 0.74 g
An orbital period of 4.511 days
Semi-major axis 0.0630 AU
Equilibrium temperature 1,468 K (1195 °C)
Distance from Earth 1,162.39 light-years
Earth Similarity Index 0.067
Travel time at Voyager 1 speed 20,498,758 years

NGTS-2 b Planet Profile

Physical Specs

Radius

17.88 R⊕

Radius (Jupiter)

1.595 R♃

Mass

235.19 M⊕

Mass (Jupiter)

0.740 M♃

Density

0.23 g/cm³

Surface Gravity

0.74 g (Earth)

Classification

Planet Type

Gas Giant

ESI Score 0.067

HZ Position Inner

Controversial No

Discovery

Year 2018

Method Transit

Facility Next-Generation Transit Survey (NGTS)

Telescope 20 cm NGTS telescope

Size rank in cohort

Rank by radius

#80of 1771

top 4.5%

This planet

17.88R⊕

Gas Giant median

13.52R⊕

Nearest-size peers

MASCARA-1 b 17.90 R⊕ WASP-93 b 17.90 R⊕ WASP-33 b 17.86 R⊕

Metric	Earth	NGTS-2 b	Jupiter
Radius (R⊕)	1.00	17.88	11.21
Mass (M⊕)	1.00	235.19	317.83
Density (g/cm³)	5.51	0.23	1.33
Surface Gravity (g)	1.00	0.74	2.53
Insolation (S⊕)	1.00	1,085.35	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	235.194 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 125739286

Gaia DR2

Gaia DR2 6220602384081327104

Gaia DR3

Gaia DR3 6220602384081327104

System

NGTS-2

Percentile among Gas Giant cohort

Radius 17.878 R⊕ · percentile 95 / cohort 1771

Mass 235.194 M⊕ · percentile 25 / cohort 1747

Orbital period 4.51 d · percentile 33 / cohort 1533

Distance 356.39 pc · percentile 66 / cohort 1759

ESI 0.067 · percentile 12 / cohort 1771

Orbit & Habitability

Orbital Dynamics

Period

4.511 days

Semi-major axis

0.0630 AU

Eccentricity

0.000

Inclination

88.50 °

Year Length

A year here lasts approximately 4.51 Earth days (1.2% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0630 AU.

Transit Fingerprint

Depth

1.117 %

Duration

4.651 h

Rp / R★

0.096190

Transit midpoint (BJD)

2,457,759.1261

Photometric dip

Transit produces a flux drop of 11,170 ppm lasting ≈ 4.65 h.

Extended Orbital Architecture

Planet / star radius ratio

0.096190

Semi-major axis / stellar radius

8.000

RV semi-amplitude (K)

65.800 m/s

Transit mid-time (BJD)

2,457,759.1261

Angular separation (arcsec)

0.17700

Eq. Temperature

1,468K

(1195 °C)

Insolation (S⊕)

1,085.35

Earth = 1.00

Earth Similarity (ESI)

0.067

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

Raynard et al. 2018

Instrument

NGTS CCD array

Publication

2018-12

Observation locale

Ground

Host System: NGTS-2

Spectral Class

F-type yellow-white

Effective Temperature

6,478 K — hotter than the Sun (5,778 K)

Estimated Age

2.17 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

1.702 R☉

Stellar Mass

1.640 M☉

Metallicity [Fe/H]

-0.06

Extended Stellar Properties

Surface gravity (log g)

4.197 dex

Stellar density

0.477 g/cm³

Systemic radial velocity

-26.36 km/s

Rotational v·sin i

15.20 km/s

Metallicity ratio

[Fe/H]

Distance

356.39 parsec

Light-years 1,162.39 ly

V-band magnitude

10.79 mag

Voyager-speed travel 20,498,758 yr

Multi-band Host Photometry — 14 bands

Astrometric Data

Parallax

2.779 mas

Total Proper Motion

21.753 mas/yr

PM Right Ascension

-21.74 mas/yr

PM Declination

-0.86 mas/yr

Galactic Cartesian (pc)

x = -0.700 · y = -0.492 · z = -0.518

Equatorial (J2000)

RA 215.12276° · Dec -31.20207°

Galactic ℓ, b

324.448° · 27.922°

Ecliptic λ, β

223.222° · -16.234°

HTM-20 index

-547270607