Key parameters at a glance

A radius of 15.13 Earth radii
A mass of 540.31 Earth masses
Surface gravity around 2.36 g
An orbital period of 4.114 days
Semi-major axis 0.0550 AU
Equilibrium temperature 2,080 K (1807 °C)
Distance from Earth 437.24 light-years
Earth Similarity Index 0.059
Travel time at Voyager 1 speed 7,710,695 years

KELT-2 A b Planet Profile

Physical Specs

Radius

15.13 R⊕

Radius (Jupiter)

1.350 R♃

Mass

540.31 M⊕

Mass (Jupiter)

1.700 M♃

Density

0.91 g/cm³

Surface Gravity

2.36 g (Earth)

Classification

Planet Type

Gas Giant

ESI Score 0.059

HZ Position Inner

Controversial No

Discovery

Year 2012

Method Transit

Facility KELT

Telescope Mamiya 645 80mm f/1.9

Size rank in cohort

Rank by radius

#220of 1771

top 12.4%

This planet

15.13R⊕

Gas Giant median

13.52R⊕

Nearest-size peers

WASP-123 b 15.13 R⊕ KELT-11 b 15.13 R⊕ WASP-108 b 15.13 R⊕

Metric	Earth	KELT-2 A b	Jupiter
Radius (R⊕)	1.00	15.13	11.21
Mass (M⊕)	1.00	540.31	317.83
Density (g/cm³)	5.51	0.91	1.33
Surface Gravity (g)	1.00	2.36	2.53
Insolation (S⊕)	1.00	3,108.45	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	540.311 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

HD 42176

HIP

HIP 29301

TIC

TIC 97735908

Gaia DR2

Gaia DR2 3438059369839738624

Gaia DR3

Gaia DR3 3438059369839738624

System

KELT-2

Percentile among Gas Giant cohort

Radius 15.132 R⊕ · percentile 88 / cohort 1771

Mass 540.311 M⊕ · percentile 51 / cohort 1747

Orbital period 4.11 d · percentile 30 / cohort 1533

Distance 134.06 pc · percentile 41 / cohort 1759

ESI 0.059 · percentile 8 / cohort 1771

Orbit & Habitability

Orbital Dynamics

Period

4.114 days

Semi-major axis

0.0550 AU

Eccentricity

0.000

Inclination

88.60 °

Year Length

A year here lasts approximately 4.11 Earth days (1.1% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0550 AU.

Transit Fingerprint

Depth

0.520 %

Duration

5.172 h

Rp / R★

0.072200

Transit midpoint (BJD)

2,459,467.1990

Photometric dip

Transit produces a flux drop of 5,200 ppm lasting ≈ 5.17 h.

Extended Orbital Architecture

Planet / star radius ratio

0.072200

Semi-major axis / stellar radius

6.480

RV semi-amplitude (K)

161.100 m/s

Transit mid-time (BJD)

2,459,467.1990

Long. of periastron (ω)

90.00°

Angular separation (arcsec)

0.41000

Eq. Temperature

2,080K

(1807 °C)

Insolation (S⊕)

3,108.45

Earth = 1.00

Earth Similarity (ESI)

0.059

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

Beatty et al. 2012

Instrument

Apogee 4K CCD Sensor

Publication

2012-09

Observation locale

Ground

Host System: KELT-2 A

Spectral Class

F-type yellow-white

Effective Temperature

6,327 K — hotter than the Sun (5,778 K)

Estimated Age

3.97 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

1.930 R☉

Stellar Mass

1.540 M☉

Metallicity [Fe/H]

0.00

Extended Stellar Properties

Surface gravity (log g)

4.500 dex

Stellar density

0.300 g/cm³

Systemic radial velocity

-47.30 km/s

Rotational v·sin i

9.00 km/s

Metallicity ratio

[Fe/H]

Distance

134.06 parsec

Light-years 437.24 ly

V-band magnitude

8.68 mag

Voyager-speed travel 7,710,695 yr

Multi-band Host Photometry — 11 bands

Astrometric Data

Parallax

7.431 mas

Total Proper Motion

16.912 mas/yr

PM Right Ascension

16.74 mas/yr

PM Declination

-2.41 mas/yr

Galactic Cartesian (pc)

x = -0.040 · y = 0.857 · z = 0.514

Equatorial (J2000)

RA 92.66402° · Dec 30.95713°

Galactic ℓ, b

180.950° · 5.708°

Ecliptic λ, β

92.300° · 7.539°

HTM-20 index

-565993200

Observation Record

Photometric series

Emission spectra

Archive notes