Confirmed Exoplanet Discovered 2016

WASP-118 b

A gas giant orbiting the f-type yellow-white WASP-118, located approximately 1,228.5 light-years from Earth.

Key parameters at a glance

  • A radius of 16.14 Earth radii
  • A mass of 163.36 Earth masses
  • Surface gravity around 0.63 g
  • An orbital period of 4.046 days
  • Semi-major axis 0.0545 AU
  • Equilibrium temperature 1,729 K (1456 °C)
  • Distance from Earth 1,228.49 light-years
  • Earth Similarity Index 0.058
  • Travel time at Voyager 1 speed 21,664,467 years

WASP-118 b Planet Profile

Physical Specs

Radius
16.14 R⊕
Radius (Jupiter)
1.440 R♃
Mass
163.36 M⊕
Mass (Jupiter)
0.514 M♃
Density
0.23 g/cm³
Surface Gravity
0.63 g (Earth)

Classification

Planet Type

Gas Giant

ESI Score 0.058
HZ Position Inner
Controversial No

Discovery

Year 2016
Method Transit
Facility SuperWASP
Telescope Canon 200mm f/1.8L

Size rank in cohort

Rank by radius

#146of 1771

top 8.2%

This planet

16.14R⊕

Gas Giant median

13.52R⊕

Nearest-size peers

Metric Earth WASP-118 b Jupiter
Radius (R⊕)1.0016.1411.21
Mass (M⊕)1.00163.36317.83
Density (g/cm³)5.510.231.33
Surface Gravity (g)1.000.632.53
Insolation (S⊕)1.006,586.470.037

Alternative Mass Estimates

Method Value Interpretation
Best measured mass 163.365 M⊕ Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 380907135

Gaia DR2

Gaia DR2 2562569564026683520

Gaia DR3

Gaia DR3 2562569564026683520

System

WASP-118

Percentile among Gas Giant cohort

Radius 16.141 R⊕ · percentile 92 / cohort 1771
Mass 163.365 M⊕ · percentile 14 / cohort 1747
Orbital period 4.05 d · percentile 29 / cohort 1533
Distance 376.66 pc · percentile 67 / cohort 1759
ESI 0.058 · percentile 8 / cohort 1771

Orbit & Habitability

Orbital Dynamics

Period
4.046 days
Semi-major axis
0.0545 AU
Eccentricity
0.000
Inclination
88.70 °

Year Length

A year here lasts approximately 4.05 Earth days (1.1% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0545 AU.

Transit Fingerprint

Depth

0.755 %

Duration

4.805 h

Impact parameter b

0.160

Rp / R★

0.080590

Transit midpoint (BJD)

2,456,787.8142

Photometric dip

Transit produces a flux drop of 7,550 ppm lasting ≈ 4.80 h.

Extended Orbital Architecture

Planet / star radius ratio

0.080590

Semi-major axis / stellar radius

6.920

Impact parameter (b)

0.160

RV semi-amplitude (K)

54.600 m/s

Transit mid-time (BJD)

2,456,787.8142

Long. of periastron (ω)

0.00°

Angular separation (arcsec)

0.14500

Eq. Temperature

1,729K

(1456 °C)

Insolation (S⊕)

6,586.47

Earth = 1.00

Earth Similarity (ESI)

0.058

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

Hay et al. 2016

Instrument

iKon-L CCD Camera

Publication

2016-12

Observation locale

Ground

Host System: WASP-118

Spectral Class

F-type yellow-white

Effective Temperature

6,410 K — hotter than the Sun (5,778 K)

Estimated Age

1.17 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

1.696 R☉

Stellar Mass

1.320 M☉

Metallicity [Fe/H]

0.16

Extended Stellar Properties

Surface gravity (log g)

4.100 dex

Stellar density

0.382 g/cm³

Systemic radial velocity

5.88 km/s

Rotational v·sin i

9.68 km/s

Rotation period

6.12 days

Metallicity ratio

[Fe/H]

Distance
376.66 parsec
Light-years 1,228.49 ly
V-band magnitude
11.01 mag
Voyager-speed travel 21,664,467 yr

Multi-band Host Photometry — 12 bands

8.411.611.62B11.01V10.92Gaia10.93Kepler10.56TESS10.09J9.85H9.79K9.75W19.78W29.77W38.40W4

Astrometric Data

Parallax

2.628 mas

Total Proper Motion

14.801 mas/yr

PM Right Ascension

2.46 mas/yr

PM Declination

-14.59 mas/yr

Galactic Cartesian (pc)

x = 0.941 · y = 0.334 · z = 0.047

Equatorial (J2000)

RA 19.55059° · Dec 2.70278°

Galactic ℓ, b

136.180° · -59.479°

Ecliptic λ, β

19.068° · -5.146°

HTM-20 index

-476830732

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