Key parameters at a glance
- A radius of 19.51 Earth radii
- A mass of 1,074.90 Earth masses
- Surface gravity around 2.82 g
- An orbital period of 3.474 days
- Semi-major axis 0.0542 AU
- Equilibrium temperature 2,262 K (1989 °C)
- Distance from Earth 444.96 light-years
- Earth Similarity Index 0.049
- Travel time at Voyager 1 speed 7,846,897 years
KELT-20 b Planet Profile
Physical Specs
Classification
Planet Type
Gas Giant
Discovery
Size rank in cohort
Rank by radius
#38of 1771
top 2.1%
This planet
19.51R⊕
Gas Giant median
13.52R⊕
Nearest-size peers
| Metric | Earth | KELT-20 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 19.51 | 11.21 |
| Mass (M⊕) | 1.00 | 1,074.90 | 317.83 |
| Density (g/cm³) | 5.51 | 0.81 | 1.33 |
| Surface Gravity (g) | 1.00 | 2.82 | 2.53 |
| Insolation (S⊕) | 1.00 | 4,362.50 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 1,074.901 M⊕ | Direct mass measurement (not derived). |
| Minimum mass (M sin i) | 1,071.723 M⊕ | Lower bound from radial-velocity fitting. |
Star Catalogue Identifiers
HD
HD 185603
HIP
HIP 96618
TIC
TIC 69679391
Gaia DR2
Gaia DR2 2033123654092592384
Gaia DR3
Gaia DR3 2033123654092592384
System
KELT-20
Percentile among Gas Giant cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 3.47 Earth days (1.0% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0542 AU.
Transit Fingerprint
Depth
1.309 %
Duration
3.576 h
Impact parameter b
0.503
Rp / R★
0.114400
Transit midpoint (BJD)
2,457,503.1200
Photometric dip
Transit produces a flux drop of 13,090 ppm lasting ≈ 3.58 h.
Extended Orbital Architecture
Planet / star radius ratio
0.114400
Semi-major axis / stellar radius
7.420
Impact parameter (b)
0.503
RV semi-amplitude (K)
311.300 m/s
Transit mid-time (BJD)
2,457,503.1200
Sky-projected obliquity (λ)
3.40°
True obliquity (ψ)
35.60°
Angular separation (arcsec)
0.39700
Eq. Temperature
2,262K
(1989 °C)
Insolation (S⊕)
4,362.50
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
Lund et al. 2017Instrument
Apogee 4K CCD Sensor
Publication
2017-11
Observation locale
Ground
Discovery cohort
Planets confirmed in 2017 at KELT-North (3 shown).
Host System: KELT-20
Spectral Class
A-type white
Effective Temperature
8,720 K — hotter than the Sun (5,778 K)
Estimated Age
0.60 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
1.565 R☉
Stellar Mass
1.760 M☉
Metallicity [Fe/H]
-0.29
Extended Stellar Properties
Surface gravity (log g)
4.290 dex
Stellar density
0.641 g/cm³
Systemic radial velocity
-23.30 km/s
Rotational v·sin i
117.40 km/s
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 11 bands
Astrometric Data
Parallax
7.301 mas
Total Proper Motion
6.892 mas/yr
PM Right Ascension
3.10 mas/yr
PM Declination
-6.16 mas/yr
Galactic Cartesian (pc)
x = 0.357 · y = -0.777 · z = 0.518
Equatorial (J2000)
RA 294.66141° · Dec 31.21920°
Galactic ℓ, b
65.808° · 4.627°
Ecliptic λ, β
305.141° · 51.692°
HTM-20 index
1394875469
Similar Worlds
HAT-P-57 b
Gas Giant · A-type white
Radius 19.50 R⊕ · 912.8 ly
WASP-178 b
Gas Giant · A-type white
Radius 20.29 R⊕ · 1,394.9 ly
bet Pic b
Gas Giant · A-type white
Radius 18.49 R⊕ · 64.4 ly
WASP-189 b
Gas Giant · A-type white
Radius 18.15 R⊕ · 325.3 ly
HAT-P-70 b
Gas Giant · A-type white
Radius 20.96 R⊕ · 1,078.7 ly
MASCARA-1 b
Gas Giant · A-type white
Radius 17.90 R⊕ · 594.5 ly