Key parameters at a glance

A radius of 15.13 Earth radii
A mass of 285.73 Earth masses
Surface gravity around 1.25 g
An orbital period of 2.978 days
Semi-major axis 0.0426 AU
Equilibrium temperature 1,500 K (1227 °C)
Distance from Earth 645.78 light-years
Earth Similarity Index 0.079
Travel time at Voyager 1 speed 11,388,256 years

WASP-123 b Planet Profile

Physical Specs

Radius

15.13 R⊕

Radius (Jupiter)

1.350 R♃

Mass

285.73 M⊕

Mass (Jupiter)

0.899 M♃

Density

0.49 g/cm³

Surface Gravity

1.25 g (Earth)

Classification

Planet Type

Gas Giant

ESI Score 0.079

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

#221of 1771

top 12.4%

This planet

15.13R⊕

Gas Giant median

13.52R⊕

Nearest-size peers

WASP-108 b 15.13 R⊕ KELT-11 b 15.13 R⊕ KELT-2 A b 15.13 R⊕

Metric	Earth	WASP-123 b	Jupiter
Radius (R⊕)	1.00	15.13	11.21
Mass (M⊕)	1.00	285.73	317.83
Density (g/cm³)	5.51	0.49	1.33
Surface Gravity (g)	1.00	1.25	2.53
Insolation (S⊕)	1.00	758.32	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	285.729 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 31858843

Gaia DR2

Gaia DR2 6756148659453907200

Gaia DR3

Gaia DR3 6756148659453907200

System

WASP-123

Percentile among Gas Giant cohort

Radius 15.132 R⊕ · percentile 87 / cohort 1771

Mass 285.729 M⊕ · percentile 32 / cohort 1747

Orbital period 2.98 d · percentile 15 / cohort 1533

Distance 198.00 pc · percentile 50 / cohort 1759

ESI 0.079 · percentile 18 / cohort 1771

Orbit & Habitability

Orbital Dynamics

Period

2.978 days

Semi-major axis

0.0426 AU

Eccentricity

0.000

Inclination

86.20 °

Year Length

A year here lasts approximately 2.98 Earth days (0.8% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0426 AU.

Transit Fingerprint

Depth

1.302 %

Duration

3.094 h

Impact parameter b

0.480

Rp / R★

0.105300

Transit midpoint (BJD)

2,456,845.1735

Photometric dip

Transit produces a flux drop of 13,022 ppm lasting ≈ 3.09 h.

Extended Orbital Architecture

Planet / star radius ratio

0.105300

Semi-major axis / stellar radius

7.290

Impact parameter (b)

0.480

RV semi-amplitude (K)

114.200 m/s

Transit mid-time (BJD)

2,456,845.1735

Angular separation (arcsec)

0.21500

Eq. Temperature

1,500K

(1227 °C)

Insolation (S⊕)

758.32

Earth = 1.00

Earth Similarity (ESI)

0.079

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

Turner et al. 2016

Instrument

iKon-L CCD Camera

Publication

2016-06

Observation locale

Ground

Discovery cohort

Planets confirmed in 2016 at SuperWASP (11 shown).

WASP-157 b · Gas Giant WASP-138 b · Gas Giant WASP-120 b · Gas Giant WASP-136 b · Gas Giant WASP-127 b · Gas Giant WASP-118 b · Gas Giant WASP-92 b · Gas Giant WASP-93 b · Gas Giant WASP-90 b · Gas Giant WASP-121 b · Gas Giant WASP-76 b · Gas Giant

Host System: WASP-123

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,740 K — cooler than the Sun (5,778 K)

Estimated Age

6.90 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

1.285 R☉

Stellar Mass

1.166 M☉

Metallicity [Fe/H]

0.18

Extended Stellar Properties

Surface gravity (log g)

4.286 dex

Stellar density

0.773 g/cm³

Systemic radial velocity

16.93 km/s

Rotational v·sin i

1.00 km/s

Metallicity ratio

[Fe/H]

Distance

198.00 parsec

Light-years 645.78 ly

V-band magnitude

11.03 mag

Voyager-speed travel 11,388,256 yr

Multi-band Host Photometry — 11 bands

Astrometric Data

Parallax

5.024 mas

Total Proper Motion

35.957 mas/yr

PM Right Ascension

-16.78 mas/yr

PM Declination

-31.80 mas/yr

Galactic Cartesian (pc)

x = 0.280 · y = -0.792 · z = -0.543

Equatorial (J2000)

RA 289.47921° · Dec -32.86012°

Galactic ℓ, b

5.196° · -19.487°

Ecliptic λ, β

286.550° · -10.533°

HTM-20 index

-1762605040