Key parameters at a glance

A radius of 1.73 Earth radii
A mass of 5.60 Earth masses
Surface gravity around 1.87 g
An orbital period of 24.737 days
Semi-major axis 0.0946 AU
Equilibrium temperature 226 K (-47 °C)
Distance from Earth 48.88 light-years
Earth Similarity Index 0.747
Travel time at Voyager 1 speed 861,965 years
Almost certainly tidally locked to its host star given the close orbit

Context from the literature

LHS 1140 b is an exoplanet orbiting within the conservative habitable zone of the red dwarf LHS 1140. Discovered in 2017 by the MEarth Project, LHS 1140 b is about 5.6 times the mass of Earth and about 70% larger in radius, putting it within the super-Earth category of planets. It was initially thought to be a dense rocky planet, but refined measurements of its mass and radius have found a lower density than previously estimated, indicating that it is likely an ocean world with 9-19% of its mass composed of water. LHS 1140 b orbits entirely within the star's habitable zone and gets 43% the incident flux of Earth. The planet is 49 light-years away and transits its star, making it an excellent candidate for atmospheric studies with ground-based and/or space telescopes.

Excerpted from Wikipedia · full article

1 sibling around LHS 1140

LHS 1140 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
LHS 1140 c	Super-Earth	1.27	1.91	3.778	422	2018
LHS 1140 b this	Super-Earth	1.73	5.60	24.737	226	2017

LHS 1140 b Planet Profile

Physical Specs

Radius

1.73 R⊕

Radius (Jupiter)

0.154 R♃

Mass

5.60 M⊕

Mass (Jupiter)

0.018 M♃

Density

5.90 g/cm³

Surface Gravity

1.87 g (Earth)

Classification

Planet Type

Super-Earth

ESI Score 0.747

HZ Position Habitable

Controversial No

Discovery

Year 2017

Method Transit

Facility MEarth Project

Telescope 0.4 m MEarth Telescope

Size rank in cohort

Rank by radius

#356of 1176

top 30.2%

This planet

1.73R⊕

Super-Earth median

1.60R⊕

Nearest-size peers

Kepler-327 d 1.73 R⊕ Kepler-1608 b 1.73 R⊕ Kepler-238 b 1.73 R⊕

Metric	Earth	LHS 1140 b	Jupiter
Radius (R⊕)	1.00	1.73	11.21
Mass (M⊕)	1.00	5.60	317.83
Density (g/cm³)	5.51	5.90	1.33
Surface Gravity (g)	1.00	1.87	2.53
Insolation (S⊕)	1.00	0.43	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	5.600 M⊕	Direct mass measurement (not derived).
Minimum mass (M sin i)	6.090 M⊕	Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

TIC

TIC 92226327

Gaia DR2

Gaia DR2 2371032916186181760

Gaia DR3

Gaia DR3 2371032916186181760

System

LHS 1140

Percentile among Super-Earth cohort

Radius 1.730 R⊕ · percentile 68 / cohort 1176

Mass 5.600 M⊕ · percentile 93 / cohort 1176

Orbital period 24.74 d · percentile 88 / cohort 1164

Distance 14.99 pc · percentile 3 / cohort 1171

ESI 0.747 · percentile 87 / cohort 1176

Orbit & Habitability

Orbital Dynamics

Period

24.737 days

Semi-major axis

0.0946 AU

Eccentricity

0.043

Inclination

89.86 °

Year Length

A year here lasts approximately 24.74 Earth days (6.8% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0946 AU.

Transit Fingerprint

Depth

0.538 %

Duration

2.150 h

Impact parameter b

0.230

Rp / R★

0.073900

Transit midpoint (BJD)

2,458,399.9300

Photometric dip

Transit produces a flux drop of 5,380 ppm lasting ≈ 2.15 h.

Extended Orbital Architecture

Planet / star radius ratio

0.073900

Semi-major axis / stellar radius

95.340

Impact parameter (b)

0.230

RV semi-amplitude (K)

3.800 m/s

Transit mid-time (BJD)

2,458,399.9300

Angular separation (arcsec)

6.31000

Eq. Temperature

226K

(-47 °C)

Insolation (S⊕)

0.43

Earth = 1.00

Earth Similarity (ESI)

0.747

0 = alien, 1 = Earth-identical

Within the conservative habitable zone — surface water would be frozen. 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

Dittmann et al. 2017

Instrument

Apogee CCD Sensor

Publication

2017-04

Observation locale

Ground

Host System: LHS 1140

Spectral Class

M-type red dwarf

Effective Temperature

3,096 K — cooler than the Sun (5,778 K)

Estimated Age

5.00 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

0.216 R☉

Stellar Mass

0.184 M☉

Metallicity [Fe/H]

-0.15

Extended Stellar Properties

Surface gravity (log g)

5.041 dex

Stellar density

25.800 g/cm³

Systemic radial velocity

-13.23 km/s

Rotation period

131.00 days

Metallicity ratio

[Fe/H]

Distance

14.99 parsec

Light-years 48.88 ly

V-band magnitude

14.15 mag

Voyager-speed travel 861,965 yr

Multi-band Host Photometry — 12 bands

Astrometric Data

Parallax

66.700 mas

Total Proper Motion

675.879 mas/yr

PM Right Ascension

317.59 mas/yr

PM Declination

-596.62 mas/yr

Galactic Cartesian (pc)

x = 0.946 · y = 0.188 · z = -0.263

Equatorial (J2000)

RA 11.24863° · Dec -15.27411°

Galactic ℓ, b

115.405° · -78.052°

Ecliptic λ, β

4.098° · -18.454°

HTM-20 index

-652728547

Wikipedia → Image: Wikimedia Commons · ESO/spaceengine.org · CC BY 4.0