Key parameters at a glance

A radius of 12.10 Earth radii
A mass of 6,674.40 Earth masses
Surface gravity around 45.59 g
An orbital period of 803.000 days
Semi-major axis 2.1000 AU
Distance from Earth 731.07 light-years
Earth Similarity Index 0.286
Travel time at Voyager 1 speed 12,892,342 years

HD 18438 b Planet Profile

Physical Specs

Radius

12.10 R⊕

Radius (Jupiter)

1.080 R♃

Mass

6,674.40 M⊕

Mass (Jupiter)

21.000 M♃

Density

20.70 g/cm³

Surface Gravity

45.59 g (Earth)

Classification

Planet Type

Gas Giant

ESI Score 0.286

HZ Position Unknown

Controversial No

Discovery

Year 2023

Method Radial Velocity

Facility Bohyunsan Optical Astronomical Observatory

Telescope 1.8 m Telescope

Size rank in cohort

Rank by radius

#1454of 1771

top 82.0%

This planet

12.10R⊕

Gas Giant median

13.52R⊕

Nearest-size peers

HD 62364 b 12.10 R⊕ HD 106515 A b 12.10 R⊕ BD+20 2457 b 12.10 R⊕

Metric	Earth	HD 18438 b	Jupiter
Radius (R⊕)	1.00	12.10	11.21
Mass (M⊕)	1.00	6,674.40	317.83
Density (g/cm³)	5.51	20.70	1.33
Surface Gravity (g)	1.00	45.59	2.53
Insolation (S⊕)	1.00	—	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Minimum mass (M sin i)	6,674.397 M⊕	Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

HD 18438

HIP

HIP 14417

TIC

TIC 297820335

Gaia DR2

Gaia DR2 567664766657362304

Gaia DR3

Gaia DR3 567664766657362304

System

HD 18438

Percentile among Gas Giant cohort

Radius 12.100 R⊕ · percentile 16 / cohort 1771

Mass 6,674.397 M⊕ · percentile 97 / cohort 1747

Orbital period 803.00 d · percentile 74 / cohort 1533

Distance 224.15 pc · percentile 53 / cohort 1759

ESI 0.286 · percentile 54 / cohort 1771

Orbit & Habitability

Orbital Dynamics

Period

803.000 days

Semi-major axis

2.1000 AU

Eccentricity

0.100

Inclination

— °

Year Length

A year here lasts about 2.20 Earth years on a mildly elliptical path at a mean orbital distance of 2.1000 AU.

Eq. Temperature

—

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.286

0 = alien, 1 = Earth-identical

Discovery Paper

Primary reference

Lee et al. 2023

Instrument

BOES Echelle Spectrograph

Publication

2023-03

Observation locale

Ground

Discovery cohort

Planets confirmed in 2023 at Bohyunsan Optical Astronomical Observatory (3 shown).

HD 36384 b · Gas Giant HD 112300 b · Gas Giant HD 6860 b · Gas Giant

Host System: HD 18438

Spectral Class

M-type red dwarf

Effective Temperature

3,860 K — cooler than the Sun (5,778 K)

Estimated Age

5.50 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

88.475 R☉

Stellar Mass

1.840 M☉

Metallicity [Fe/H]

-0.40

Extended Stellar Properties

Surface gravity (log g)

0.900 dex

Rotational v·sin i

5.50 km/s

Metallicity ratio

[Fe/H]

Distance

224.15 parsec

Light-years 731.07 ly

V-band magnitude

5.50 mag

Voyager-speed travel 12,892,342 yr

Multi-band Host Photometry — 11 bands

Astrometric Data

Parallax

4.443 mas

Total Proper Motion

36.895 mas/yr

PM Right Ascension

-35.29 mas/yr

PM Declination

10.76 mas/yr

Galactic Cartesian (pc)

x = 0.126 · y = 0.133 · z = 0.983

Equatorial (J2000)

RA 46.53184° · Dec 79.41858°

Galactic ℓ, b

129.084° · 18.193°

Ecliptic λ, β

76.169° · 58.089°

HTM-20 index

-220843512

Similar Worlds

UCAC3 113-933 b

Gas Giant · M-type red dwarf

Radius 12.10 R⊕ · 171.5 ly

LP 261-75 b

Gas Giant · M-type red dwarf

Radius 12.10 R⊕ · 110.7 ly

2MASS J11550485-7919108 b

Gas Giant · M-type red dwarf

Radius 12.10 R⊕ · 329.0 ly

HD 41004 B b

Gas Giant · M-type red dwarf

Radius 12.10 R⊕ · 135.5 ly

Gaia-5 b

Gas Giant · M-type red dwarf

Radius 12.10 R⊕ · 134.3 ly

ROXs 12 b

Gas Giant · M-type red dwarf

Radius 12.20 R⊕ · 445.7 ly

Explore Related Categories

Gas Giant Planets Radial Velocity Discoveries Bohyunsan Optical Astronomical Observatory Mission M-type red dwarf Hosts