Key parameters at a glance

A radius of 2.61 Earth radii
A mass of 22.70 Earth masses
Surface gravity around 3.33 g
An orbital period of 35.613 days
Semi-major axis 0.1915 AU
Equilibrium temperature 422 K (149 °C)
Distance from Earth 53.23 light-years
Earth Similarity Index 0.589
Travel time at Voyager 1 speed 938,687 years
Almost certainly tidally locked to its host star given the close orbit

1 sibling around GJ 143

GJ 143 b shares its host star with 1 other confirmed planet. Side-by-side measurements below.

Planet	Type	Radius (R⊕)	Mass (M⊕)	Period (d)	Eq. T (K)	Year
HD 21749 c	Rocky Terrestrial	0.89	3.70	7.790	701	2019
GJ 143 b this	Sub-Neptune	2.61	22.70	35.613	422	2019

GJ 143 b Planet Profile

Physical Specs

Radius

2.61 R⊕

Radius (Jupiter)

0.233 R♃

Mass

22.70 M⊕

Mass (Jupiter)

0.071 M♃

Density

7.00 g/cm³

Surface Gravity

3.33 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.589

HZ Position Inner

Controversial No

Discovery

Year 2019

Method Transit

Facility Transiting Exoplanet Survey Satellite (TESS)

Telescope 0.1 m TESS Telescope

Size rank in cohort

Rank by radius

#999of 1978

top 50.5%

This planet

2.61R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-214 b 2.61 R⊕ TOI-2048 b 2.61 R⊕ TOI-1422 c 2.61 R⊕

Metric	Earth	GJ 143 b	Jupiter
Radius (R⊕)	1.00	2.61	11.21
Mass (M⊕)	1.00	22.70	317.83
Density (g/cm³)	5.51	7.00	1.33
Surface Gravity (g)	1.00	3.33	2.53
Insolation (S⊕)	1.00	7.04	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	22.700 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

HD 21749

HIP

HIP 16069

TIC

TIC 279741379

Gaia DR2

Gaia DR2 4673947174316727040

Gaia DR3

Gaia DR3 4673947174316727040

System

GJ 143

Percentile among Sub-Neptune cohort

Radius 2.610 R⊕ · percentile 49 / cohort 1978

Mass 22.700 M⊕ · percentile 96 / cohort 1978

Orbital period 35.61 d · percentile 78 / cohort 1946

Distance 16.32 pc · percentile 3 / cohort 1975

ESI 0.589 · percentile 81 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

35.613 days

Semi-major axis

0.1915 AU

Eccentricity

0.188

Inclination

89.33 °

Year Length

A year here lasts approximately 35.61 Earth days (9.8% of a terrestrial year) on a mildly elliptical path at a mean orbital distance of 0.1915 AU.

Transit Fingerprint

Depth

0.140 %

Duration

3.230 h

Impact parameter b

0.587

Rp / R★

0.035000

Transit midpoint (BJD)

2,458,385.9250

Photometric dip

Transit produces a flux drop of 1,398 ppm lasting ≈ 3.23 h.

Extended Orbital Architecture

Planet / star radius ratio

0.035000

Semi-major axis / stellar radius

60.100

Impact parameter (b)

0.587

RV semi-amplitude (K)

5.510 m/s

Transit mid-time (BJD)

2,458,385.9250

Long. of periastron (ω)

98.00°

Angular separation (arcsec)

11.70000

Eq. Temperature

422K

(149 °C)

Insolation (S⊕)

7.04

Earth = 1.00

Earth Similarity (ESI)

0.589

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — the surface is too hot to retain surface water. Close-orbiting tidally-locked around a cool host.

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

Trifonov et al. 2019

Instrument

TESS CCD Array

Publication

2019-02

Observation locale

Space

Discovery cohort

Planets confirmed in 2019 at Transiting Exoplanet Survey Satellite (TESS) (12 shown).

LP 791-18 c · Sub-Neptune LTT 1445 A b · Super-Earth TOI-270 d · Sub-Neptune L 98-59 d · Super-Earth GJ 357 b · Rocky Terrestrial HD 23472 c · Super-Earth L 98-59 c · Super-Earth LP 791-18 b · Rocky Terrestrial TOI-270 c · Sub-Neptune HD 23472 b · Sub-Neptune TOI-270 b · Super-Earth L 98-59 b · Rocky Terrestrial

Host System: GJ 143

Spectral Class

K-type orange

Effective Temperature

4,640 K — cooler than the Sun (5,778 K)

Estimated Age

3.80 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

0.695 R☉

Stellar Mass

0.730 M☉

Metallicity [Fe/H]

0.00

Extended Stellar Properties

Surface gravity (log g)

4.613 dex

Stellar density

3.030 g/cm³

Systemic radial velocity

59.46 km/s

Metallicity ratio

[Fe/H]

Distance

16.32 parsec

Light-years 53.23 ly

V-band magnitude

8.08 mag

Voyager-speed travel 938,687 yr

Multi-band Host Photometry — 8 bands

Astrometric Data

Parallax

61.246 mas

Total Proper Motion

432.806 mas/yr

PM Right Ascension

355.08 mas/yr

PM Declination

-247.46 mas/yr

Galactic Cartesian (pc)

x = 0.276 · y = 0.350 · z = -0.895

Equatorial (J2000)

RA 51.75019° · Dec -63.50017°

Galactic ℓ, b

279.230° · -45.821°

Ecliptic λ, β

352.878° · -73.836°

HTM-20 index

-1611504001

Observation Record

Photometric series

Stellar spectra

Archive notes

Similar Worlds

Kepler-257 b

Sub-Neptune · K-type orange

Radius 2.61 R⊕ · 2,544.9 ly

Kepler-242 b

Sub-Neptune · K-type orange

Radius 2.61 R⊕ · 1,957.7 ly

Kepler-970 b

Sub-Neptune · K-type orange

Radius 2.61 R⊕ · 1,081.4 ly

K2-54 b

Sub-Neptune · K-type orange

Radius 2.61 R⊕ · 570.6 ly

HD 110067 g

Sub-Neptune · K-type orange

Radius 2.61 R⊕ · 104.9 ly

HD 110067 f

Sub-Neptune · K-type orange

Radius 2.60 R⊕ · 104.9 ly

Explore Related Categories

Sub-Neptune Planets Transit Discoveries Transiting Exoplanet Survey Satellite (TESS) Mission K-type orange Hosts