Key parameters at a glance

A radius of 11.99 Earth radii
A mass of 921.71 Earth masses
Surface gravity around 6.41 g
An orbital period of 4.435 days
Semi-major axis 0.0580 AU
Equilibrium temperature 1,448 K (1175 °C)
Distance from Earth 1,986.71 light-years
Earth Similarity Index 0.113
Travel time at Voyager 1 speed 35,035,585 years

NGTS-9 b Planet Profile

Physical Specs

Radius

11.99 R⊕

Radius (Jupiter)

1.070 R♃

Mass

921.71 M⊕

Mass (Jupiter)

2.900 M♃

Density

2.93 g/cm³

Surface Gravity

6.41 g (Earth)

Classification

Planet Type

Gas Giant

ESI Score 0.113

HZ Position Inner

Controversial No

Discovery

Year 2019

Method Transit

Facility Next-Generation Transit Survey (NGTS)

Telescope 20 cm NGTS telescope

Size rank in cohort

Rank by radius

#1510of 1771

top 85.2%

This planet

11.99R⊕

Gas Giant median

13.52R⊕

Nearest-size peers

WASP-158 b 11.99 R⊕ TOI-892 b 11.99 R⊕ WASP-150 b 11.99 R⊕

Metric	Earth	NGTS-9 b	Jupiter
Radius (R⊕)	1.00	11.99	11.21
Mass (M⊕)	1.00	921.71	317.83
Density (g/cm³)	5.51	2.93	1.33
Surface Gravity (g)	1.00	6.41	2.53
Insolation (S⊕)	1.00	729.00	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	921.707 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 176685457

Gaia DR2

Gaia DR2 5678340222972504832

Gaia DR3

Gaia DR3 5678340222972504832

System

NGTS-9

Percentile among Gas Giant cohort

Radius 11.994 R⊕ · percentile 15 / cohort 1771

Mass 921.707 M⊕ · percentile 65 / cohort 1747

Orbital period 4.44 d · percentile 33 / cohort 1533

Distance 609.13 pc · percentile 79 / cohort 1759

ESI 0.113 · percentile 30 / cohort 1771

Orbit & Habitability

Orbital Dynamics

Period

4.435 days

Semi-major axis

0.0580 AU

Eccentricity

0.060

Inclination

84.10 °

Year Length

A year here lasts approximately 4.44 Earth days (1.2% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0580 AU.

Transit Fingerprint

Depth

0.641 %

Duration

2.050 h

Rp / R★

0.080000

Transit midpoint (BJD)

2,457,671.8109

Photometric dip

Transit produces a flux drop of 6,410 ppm lasting ≈ 2.05 h.

Extended Orbital Architecture

Planet / star radius ratio

0.080000

Semi-major axis / stellar radius

9.060

RV semi-amplitude (K)

293.440 m/s

Transit mid-time (BJD)

2,457,671.8109

Angular separation (arcsec)

0.09520

Eq. Temperature

1,448K

(1175 °C)

Insolation (S⊕)

729.00

Earth = 1.00

Earth Similarity (ESI)

0.113

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

Costes et al. 2020

Instrument

NGTS CCD array

Publication

2020-01

Observation locale

Ground

Discovery cohort

Planets confirmed in 2019 at Next-Generation Transit Survey (NGTS) (4 shown).

NGTS-4 b · Sub-Neptune NGTS-5 b · Gas Giant NGTS-8 b · Gas Giant NGTS-6 b · Gas Giant

Host System: NGTS-9

Spectral Class

F-type yellow-white

Effective Temperature

6,330 K — hotter than the Sun (5,778 K)

Estimated Age

0.96 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

1.380 R☉

Stellar Mass

1.340 M☉

Metallicity [Fe/H]

0.31

Extended Stellar Properties

Surface gravity (log g)

4.370 dex

Stellar density

0.646 g/cm³

Systemic radial velocity

38.79 km/s

Rotational v·sin i

6.38 km/s

Metallicity ratio

[Fe/H]

Distance

609.13 parsec

Light-years 1,986.71 ly

V-band magnitude

12.87 mag

Voyager-speed travel 35,035,585 yr

Multi-band Host Photometry — 14 bands

Astrometric Data

Parallax

1.614 mas

Total Proper Motion

6.317 mas/yr

PM Right Ascension

-6.08 mas/yr

PM Declination

1.72 mas/yr

Galactic Cartesian (pc)

x = -0.743 · y = 0.582 · z = -0.331

Equatorial (J2000)

RA 141.92064° · Dec -19.34765°

Galactic ℓ, b

250.619° · 22.215°

Ecliptic λ, β

151.564° · -32.373°

HTM-20 index

916925540