Key parameters at a glance

A radius of 1.38 Earth radii
A mass of 2.48 Earth masses
Surface gravity around 1.30 g
An orbital period of 3.148 days
Semi-major axis 0.0280 AU
Distance from Earth 20.54 light-years
Earth Similarity Index 0.923
Travel time at Voyager 1 speed 362,252 years
Almost certainly tidally locked to its host star given the close orbit

Context from the literature

Gliese 581e or Gl 581e is an exoplanet orbiting within the Gliese 581 system, located 20.5 light-years away from Earth in the Libra constellation. It is the third planet discovered in the system and the first in order from the star.

Excerpted from Wikipedia · full article

2 siblings around GJ 581

GJ 581 e shares its host star with 2 other confirmed planets. Side-by-side measurements below.

Planet	Type	Radius (R⊕)	Mass (M⊕)	Period (d)	Eq. T (K)	Year
GJ 581 e this	Super-Earth	1.38	2.48	3.148	—	2009
GJ 581 b	Neptune-like	4.79	20.50	5.369	—	2005
GJ 581 c	Sub-Neptune	2.50	6.81	12.921	—	2007

GJ 581 e Planet Profile

Physical Specs

Radius

1.38 R⊕

Radius (Jupiter)

0.123 R♃

Mass

2.48 M⊕

Mass (Jupiter)

0.008 M♃

Density

5.19 g/cm³

Surface Gravity

1.30 g (Earth)

Classification

Planet Type

Super-Earth

ESI Score 0.923

HZ Position Unknown

Controversial No

Discovery

Year 2009

Method Radial Velocity

Facility La Silla Observatory

Telescope 3.6 m ESO Telescope

Size rank in cohort

Rank by radius

#953of 1176

top 81.0%

This planet

1.38R⊕

Super-Earth median

1.60R⊕

Nearest-size peers

Kepler-402 d 1.38 R⊕ Kepler-84 d 1.38 R⊕ Kepler-353 c 1.38 R⊕

Metric	Earth	GJ 581 e	Jupiter
Radius (R⊕)	1.00	1.38	11.21
Mass (M⊕)	1.00	2.48	317.83
Density (g/cm³)	5.51	5.19	1.33
Surface Gravity (g)	1.00	1.30	2.53
Insolation (S⊕)	1.00	—	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	2.480 M⊕	Direct mass measurement (not derived).
Minimum mass (M sin i)	1.700 M⊕	Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

HIP

HIP 74995

TIC

TIC 36853511

Gaia DR2

Gaia DR2 6322070093095493504

Gaia DR3

Gaia DR3 6322070093095493504

System

GJ 581

Percentile among Super-Earth cohort

Radius 1.380 R⊕ · percentile 18 / cohort 1176

Mass 2.480 M⊕ · percentile 18 / cohort 1176

Orbital period 3.15 d · percentile 23 / cohort 1164

Distance 6.30 pc · percentile 1 / cohort 1171

ESI 0.923 · percentile 98 / cohort 1176

Orbit & Habitability

Orbital Dynamics

Period

3.148 days

Semi-major axis

0.0280 AU

Eccentricity

0.012

Inclination

47.00 °

Year Length

A year here lasts approximately 3.15 Earth days (0.9% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0280 AU.

Eq. Temperature

—

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.923

0 = alien, 1 = Earth-identical

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

Discovery Paper

Primary reference

Mayor et al. 2009

Instrument

HARPS Spectrograph

Publication

2009-11

Observation locale

Ground

Discovery cohort

Planets confirmed in 2009 at La Silla Observatory (12 shown).

HD 125612 c · Neptune-like HD 90156 b · Neptune-like HD 147018 c · Gas Giant HD 103197 b · Neptune-like HD 125612 d · Gas Giant HIP 70849 b · Gas Giant HD 85390 b · Neptune-like HD 190984 b · Gas Giant HD 171238 b · Gas Giant HD 290327 b · Gas Giant HD 147018 b · Gas Giant HD 110014 b · Gas Giant

Host System: GJ 581

Spectral Class

M-type red dwarf

Effective Temperature

3,500 K — cooler than the Sun (5,778 K)

Estimated Age

4.30 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

0.302 R☉

Stellar Mass

0.295 M☉

Metallicity [Fe/H]

-0.08

Extended Stellar Properties

Surface gravity (log g)

4.970 dex

Stellar density

12.224 g/cm³

Systemic radial velocity

9.75 km/s

Rotational v·sin i

2.00 km/s

Rotation period

132.50 days

Activity index (log R'HK)

-5.480

Metallicity ratio

[Fe/H]

Distance

6.30 parsec

Light-years 20.54 ly

V-band magnitude

10.57 mag

Voyager-speed travel 362,252 yr

Multi-band Host Photometry — 12 bands

Astrometric Data

Parallax

158.749 mas

Total Proper Motion

1,225.326 mas/yr

PM Right Ascension

-1,221.47 mas/yr

PM Declination

-97.13 mas/yr

Galactic Cartesian (pc)

x = -0.639 · y = -0.757 · z = -0.134

Equatorial (J2000)

RA 229.85647° · Dec -7.72269°

Galactic ℓ, b

354.072° · 40.022°

Ecliptic λ, β

229.513° · 10.255°

HTM-20 index

2005289755

Observation Record

Photometric series

RV measurements

Stellar spectra

Wikipedia → Image: Wikimedia Commons · Aldaron, a.k.a. Aldaron · CC BY-SA 3.0