Key parameters at a glance
- A radius of 3.18 Earth radii
- A mass of 20.60 Earth masses
- Surface gravity around 2.04 g
- An orbital period of 1.337 days
- Semi-major axis 0.0190 AU
- Equilibrium temperature 1,650 K (1377 °C)
- Distance from Earth 915.05 light-years
- Earth Similarity Index 0.140
- Travel time at Voyager 1 speed 16,136,852 years
- Almost certainly tidally locked to its host star given the close orbit
NGTS-4 b Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#367of 1978
top 18.5%
This planet
3.18R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | NGTS-4 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 3.18 | 11.21 |
| Mass (M⊕) | 1.00 | 20.60 | 317.83 |
| Density (g/cm³) | 5.51 | 3.45 | 1.33 |
| Surface Gravity (g) | 1.00 | 2.04 | 2.53 |
| Insolation (S⊕) | 1.00 | 886.98 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 20.600 M⊕ | Direct mass measurement (not derived). |
Star Catalogue Identifiers
TIC
TIC 143143769
Gaia DR2
Gaia DR2 2891248292906892032
Gaia DR3
Gaia DR3 2891248292906892032
System
NGTS-4
Percentile among Sub-Neptune cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 1.34 Earth days (0.4% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0190 AU.
Transit Fingerprint
Depth
0.123 %
Duration
1.800 h
Impact parameter b
0.350
Rp / R★
0.035000
Transit midpoint (BJD)
2,457,607.9975
Photometric dip
Transit produces a flux drop of 1,227 ppm lasting ≈ 1.80 h.
Extended Orbital Architecture
Planet / star radius ratio
0.035000
Semi-major axis / stellar radius
4.790
Impact parameter (b)
0.350
RV semi-amplitude (K)
13.700 m/s
Transit mid-time (BJD)
2,457,607.9975
Long. of periastron (ω)
0.00°
Angular separation (arcsec)
0.06770
Eq. Temperature
1,650K
(1377 °C)
Insolation (S⊕)
886.98
Earth = 1.00
Earth Similarity (ESI)
0.140
0 = alien, 1 = Earth-identical
Inside the inner HZ boundary (too hot for liquid water) — the dayside is scorched. Close-orbiting tidally-locked around a cool host.
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
West et al. 2019Instrument
NGTS CCD array
Publication
2019-07
Observation locale
Ground
Discovery cohort
Planets confirmed in 2019 at Next-Generation Transit Survey (NGTS) (4 shown).
Host System: NGTS-4
Spectral Class
K-type orange
Effective Temperature
5,143 K — cooler than the Sun (5,778 K)
Estimated Age
—
Stellar Radius
0.840 R☉
Stellar Mass
0.750 M☉
Metallicity [Fe/H]
-0.28
Extended Stellar Properties
Surface gravity (log g)
4.500 dex
Stellar density
1.910 g/cm³
Systemic radial velocity
111.20 km/s
Rotational v·sin i
2.75 km/s
Metallicity ratio
[M/H]
Multi-band Host Photometry — 11 bands
Astrometric Data
Parallax
3.536 mas
Total Proper Motion
18.420 mas/yr
PM Right Ascension
-16.88 mas/yr
PM Declination
-7.37 mas/yr
Galactic Cartesian (pc)
x = 0.006 · y = 0.859 · z = -0.512
Equatorial (J2000)
RA 89.59889° · Dec -30.81180°
Galactic ℓ, b
236.579° · -24.135°
Ecliptic λ, β
89.407° · -54.250°
HTM-20 index
-531502396
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