Key parameters at a glance

A radius of 3.69 Earth radii
A mass of 13.15 Earth masses
Surface gravity around 0.97 g
An orbital period of 3.718 days
Semi-major axis 0.0226 AU
Distance from Earth 51.40 light-years
Earth Similarity Index 0.570
Travel time at Voyager 1 speed 906,512 years
Almost certainly tidally locked to its host star given the close orbit

Context from the literature

LHS 3154 b is a Neptune-sized exoplanet orbiting the red dwarf LHS 3154. It is located about 50 light-years from Earth, in the constellation of Hercules. As it is a massive planet that orbits very close to a low-mass star, it is challenging current models about exoplanet formation, as it would require 10 times more mass than there was in the protoplanetary disk where the planet formed.

Excerpted from Wikipedia · full article

LHS 3154 b Planet Profile

Physical Specs

Radius

3.69 R⊕

Radius (Jupiter)

0.329 R♃

Mass

13.15 M⊕

Mass (Jupiter)

0.041 M♃

Density

1.44 g/cm³

Surface Gravity

0.97 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.570

HZ Position Unknown

Controversial No

Discovery

Year 2023

Method Radial Velocity

Facility McDonald Observatory

Telescope 9.2 m Hobby-Eberly Telescope

Size rank in cohort

Rank by radius

#92of 1978

top 4.6%

This planet

3.69R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-222 d 3.69 R⊕ Kepler-1627 b 3.69 R⊕ HD 104067 c 3.69 R⊕

Metric	Earth	LHS 3154 b	Jupiter
Radius (R⊕)	1.00	3.69	11.21
Mass (M⊕)	1.00	13.15	317.83
Density (g/cm³)	5.51	1.44	1.33
Surface Gravity (g)	1.00	0.97	2.53
Insolation (S⊕)	1.00	—	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Minimum mass (M sin i)	13.150 M⊕	Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

TIC

TIC 24108819

Gaia DR2

Gaia DR2 1380293091823646720

Gaia DR3

Gaia DR3 1380293091823646720

System

LHS 3154

Percentile among Sub-Neptune cohort

Radius 3.690 R⊕ · percentile 95 / cohort 1978

Mass 13.150 M⊕ · percentile 88 / cohort 1978

Orbital period 3.72 d · percentile 7 / cohort 1946

Distance 15.76 pc · percentile 3 / cohort 1975

ESI 0.570 · percentile 79 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

3.718 days

Semi-major axis

0.0226 AU

Eccentricity

0.076

Inclination

— °

Year Length

A year here lasts approximately 3.72 Earth days (1.0% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0226 AU.

Extended Orbital Architecture

RV semi-amplitude (K)

23.400 m/s

Transit mid-time (BJD)

2,458,874.0000

Long. of periastron (ω)

82.00°

Angular separation (arcsec)

1.44000

Eq. Temperature

—

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.570

0 = alien, 1 = Earth-identical

Insufficient insolation data. Close-orbiting tidally-locked around a cool host.

Discovery Paper

Primary reference

Stef Aacute Nsson et al. 2023

Instrument

Habitable Zone Planet Finder (HPF) spectrograph

Publication

2023-12

Observation locale

Ground

Discovery cohort

Planets confirmed in 2023 at McDonald Observatory (2 shown).

BD+37 3172 b · Gas Giant BD+42 2315 b · Gas Giant

Host System: LHS 3154

Spectral Class

M-type red dwarf

Effective Temperature

2,861 K — cooler than the Sun (5,778 K)

Estimated Age

5.00 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

0.141 R☉

Stellar Mass

0.112 M☉

Metallicity [Fe/H]

—

Extended Stellar Properties

Surface gravity (log g)

5.200 dex

Stellar density

58.146 g/cm³

Systemic radial velocity

-42.05 km/s

Rotational v·sin i

2.00 km/s

Rotation period

114.00 days

Distance

15.76 parsec

Light-years 51.40 ly

V-band magnitude

17.65 mag

Voyager-speed travel 906,512 yr

Multi-band Host Photometry — 6 bands

Astrometric Data

Parallax

63.421 mas

Total Proper Motion

734.519 mas/yr

PM Right Ascension

-716.22 mas/yr

PM Declination

162.94 mas/yr

Galactic Cartesian (pc)

x = -0.359 · y = -0.665 · z = 0.655

Equatorial (J2000)

RA 241.63673° · Dec 40.90682°

Galactic ℓ, b

64.967° · 47.889°

Ecliptic λ, β

224.241° · 59.921°

HTM-20 index

-165666931

Wikipedia → Image: Wikimedia Commons · Vue d'artiste de l'article Penn State "Discovery of planet too… · CC BY-SA 4.0