Key parameters at a glance

A radius of 18.16 Earth radii
A mass of 209.77 Earth masses
Surface gravity around 0.64 g
An orbital period of 3.244 days
Semi-major axis 0.0455 AU
Equilibrium temperature 1,675 K (1402 °C)
Distance from Earth 644.39 light-years
Earth Similarity Index 0.053
Travel time at Voyager 1 speed 11,363,869 years

KELT-8 b Planet Profile

Physical Specs

Radius

18.16 R⊕

Radius (Jupiter)

1.620 R♃

Mass

209.77 M⊕

Mass (Jupiter)

0.660 M♃

Density

0.17 g/cm³

Surface Gravity

0.64 g (Earth)

Classification

Planet Type

Gas Giant

ESI Score 0.053

HZ Position Inner

Controversial No

Discovery

Year 2015

Method Transit

Facility KELT

Telescope Mamiya 645 80mm f/1.9

Size rank in cohort

Rank by radius

#64of 1771

top 3.6%

This planet

18.16R⊕

Gas Giant median

13.52R⊕

Nearest-size peers

WASP-82 b 18.16 R⊕ WASP-189 b 18.15 R⊕ Kepler-7 b 18.18 R⊕

Metric	Earth	KELT-8 b	Jupiter
Radius (R⊕)	1.00	18.16	11.21
Mass (M⊕)	1.00	209.77	317.83
Density (g/cm³)	5.51	0.17	1.33
Surface Gravity (g)	1.00	0.64	2.53
Insolation (S⊕)	1.00	983.31	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	209.768 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

HD 343246

TIC

TIC 358516596

Gaia DR2

Gaia DR2 4534144923690481408

Gaia DR3

Gaia DR3 4534144923690481408

System

KELT-8

Percentile among Gas Giant cohort

Radius 18.159 R⊕ · percentile 96 / cohort 1771

Mass 209.768 M⊕ · percentile 21 / cohort 1747

Orbital period 3.24 d · percentile 19 / cohort 1533

Distance 197.57 pc · percentile 50 / cohort 1759

ESI 0.053 · percentile 6 / cohort 1771

Orbit & Habitability

Orbital Dynamics

Period

3.244 days

Semi-major axis

0.0455 AU

Eccentricity

0.040

Inclination

82.65 °

Year Length

A year here lasts approximately 3.24 Earth days (0.9% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0455 AU.

Transit Fingerprint

Depth

1.300 %

Duration

3.677 h

Impact parameter b

0.741

Rp / R★

0.111500

Transit midpoint (BJD)

2,457,986.4674

Photometric dip

Transit produces a flux drop of 13,000 ppm lasting ≈ 3.68 h.

Extended Orbital Architecture

Planet / star radius ratio

0.111500

Semi-major axis / stellar radius

5.900

Impact parameter (b)

0.741

RV semi-amplitude (K)

104.000 m/s

Transit mid-time (BJD)

2,457,986.4674

Long. of periastron (ω)

85.00°

Angular separation (arcsec)

0.23000

Eq. Temperature

1,675K

(1402 °C)

Insolation (S⊕)

983.31

Earth = 1.00

Earth Similarity (ESI)

0.053

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

Fulton et al. 2015

Instrument

Apogee 4K CCD Sensor

Publication

2015-09

Observation locale

Ground

Host System: KELT-8

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,754 K — cooler than the Sun (5,778 K)

Estimated Age

5.40 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

1.460 R☉

Stellar Mass

0.810 M☉

Metallicity [Fe/H]

0.27

Extended Stellar Properties

Surface gravity (log g)

4.080 dex

Stellar density

0.370 g/cm³

Systemic radial velocity

-31.20 km/s

Rotational v·sin i

3.70 km/s

Metallicity ratio

[Fe/H]

Distance

197.57 parsec

Light-years 644.39 ly

V-band magnitude

10.85 mag

Voyager-speed travel 11,363,869 yr

Multi-band Host Photometry — 11 bands

Astrometric Data

Parallax

5.033 mas

Total Proper Motion

34.437 mas/yr

PM Right Ascension

-14.58 mas/yr

PM Declination

-31.20 mas/yr

Galactic Cartesian (pc)

x = 0.210 · y = -0.888 · z = 0.409

Equatorial (J2000)

RA 283.30545° · Dec 24.12725°

Galactic ℓ, b

54.841° · 10.374°

Ecliptic λ, β

287.846° · 46.745°

HTM-20 index

11887328