Key parameters at a glance
- A radius of 17.60 Earth radii
- A mass of 375.04 Earth masses
- Surface gravity around 1.21 g
- An orbital period of 2.872 days
- Semi-major axis 0.0455 AU
- Equilibrium temperature 2,085 K (1812 °C)
- Distance from Earth 1,048.19 light-years
- Earth Similarity Index 0.049
- Travel time at Voyager 1 speed 18,484,779 years
KELT-18 b Planet Profile
Physical Specs
Classification
Planet Type
Gas Giant
Discovery
Size rank in cohort
Rank by radius
#91of 1771
top 5.1%
This planet
17.60R⊕
Gas Giant median
13.52R⊕
Nearest-size peers
| Metric | Earth | KELT-18 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 17.60 | 11.21 |
| Mass (M⊕) | 1.00 | 375.04 | 317.83 |
| Density (g/cm³) | 5.51 | 0.38 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.21 | 2.53 |
| Insolation (S⊕) | 1.00 | 3,152.00 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 375.039 M⊕ | Direct mass measurement (not derived). |
| Minimum mass (M sin i) | 375.039 M⊕ | Lower bound from radial-velocity fitting. |
| Computed mass | 375.114 M⊕ | Model-computed mass (e.g. from mass-radius relation). |
Star Catalogue Identifiers
TIC
TIC 293687315
Gaia DR2
Gaia DR2 1612165353793791488
Gaia DR3
Gaia DR3 1612165353793791488
System
KELT-18
Percentile among Gas Giant cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 2.87 Earth days (0.8% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0455 AU.
Transit Fingerprint
Depth
0.716 %
Duration
4.644 h
Impact parameter b
0.102
Rp / R★
0.084620
Transit midpoint (BJD)
2,457,542.5250
Photometric dip
Transit produces a flux drop of 7,160 ppm lasting ≈ 4.64 h.
Extended Orbital Architecture
Planet / star radius ratio
0.084620
Semi-major axis / stellar radius
5.138
Impact parameter (b)
0.102
RV semi-amplitude (K)
127.000 m/s
Transit mid-time (BJD)
2,457,542.5250
Sky-projected obliquity (λ)
-94.80°
True obliquity (ψ)
91.70°
Angular separation (arcsec)
0.14200
Eq. Temperature
2,085K
(1812 °C)
Insolation (S⊕)
3,152.00
Earth = 1.00
Earth Similarity (ESI)
0.049
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
Mcleod et al. 2017Instrument
Apogee 4K CCD Sensor
Publication
2017-06
Observation locale
Ground
Discovery cohort
Planets confirmed in 2017 at KELT-North (3 shown).
Host System: KELT-18
Spectral Class
F-type yellow-white
Effective Temperature
6,670 K — hotter than the Sun (5,778 K)
Estimated Age
1.90 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
1.908 R☉
Stellar Mass
1.524 M☉
Metallicity [Fe/H]
0.09
Extended Stellar Properties
Surface gravity (log g)
4.060 dex
Stellar density
0.311 g/cm³
Systemic radial velocity
-11.60 km/s
Rotational v·sin i
12.30 km/s
Rotation period
8.00 days
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 15 bands
Astrometric Data
Parallax
3.083 mas
Total Proper Motion
20.408 mas/yr
PM Right Ascension
-19.45 mas/yr
PM Declination
6.18 mas/yr
Galactic Cartesian (pc)
x = -0.409 · y = -0.303 · z = 0.861
Equatorial (J2000)
RA 216.52382° · Dec 59.44427°
Galactic ℓ, b
102.715° · 53.810°
Ecliptic λ, β
170.964° · 65.565°
HTM-20 index
1112017347
Similar Worlds
HATS-39 b
Gas Giant · F-type yellow-white
Radius 17.60 R⊕ · 2,865.3 ly
WASP-172 b
Gas Giant · F-type yellow-white
Radius 17.60 R⊕ · 1,755.1 ly
HAT-P-39 b
Gas Giant · F-type yellow-white
Radius 17.61 R⊕ · 2,273.3 ly
KELT-3 b
Gas Giant · F-type yellow-white
Radius 17.49 R⊕ · 685.7 ly
WASP-167 b
Gas Giant · F-type yellow-white
Radius 17.71 R⊕ · 1,381.4 ly
HATS-40 b
Gas Giant · F-type yellow-white
Radius 17.71 R⊕ · 4,378.0 ly