Key parameters at a glance

A radius of 1.45 Earth radii
A mass of 2.70 Earth masses
Surface gravity around 1.28 g
An orbital period of 18.314 days
Semi-major axis 0.1257 AU
Equilibrium temperature 660 K (387 °C)
Distance from Earth 19.58 light-years
Earth Similarity Index 0.463
Travel time at Voyager 1 speed 345,266 years

Context from the literature

82 G. Eridani is a star 19.7 light-years away from Earth in the constellation Eridanus. It is a main-sequence star with a stellar classification of G6 V, and it hosts a system of three confirmed planets and a dust disk.

Excerpted from Wikipedia · full article

2 siblings around HD 20794

HD 20794 b 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
HD 20794 b this	Super-Earth	1.45	2.70	18.314	660	2011
HD 20794 d	Sub-Neptune	2.04	4.80	89.680	388	2011
HD 20794 f	Sub-Neptune	2.28	5.82	647.600	—	2025

HD 20794 b Planet Profile

Physical Specs

Radius

1.45 R⊕

Radius (Jupiter)

0.129 R♃

Mass

2.70 M⊕

Mass (Jupiter)

0.009 M♃

Density

4.87 g/cm³

Surface Gravity

1.28 g (Earth)

Classification

Planet Type

Super-Earth

ESI Score 0.463

HZ Position Unknown

Controversial No

Discovery

Year 2011

Method Radial Velocity

Facility La Silla Observatory

Telescope 3.6 m ESO Telescope

Size rank in cohort

Rank by radius

#837of 1176

top 71.1%

This planet

1.45R⊕

Super-Earth median

1.60R⊕

Nearest-size peers

Kepler-1226 b 1.45 R⊕ Kepler-361 b 1.45 R⊕ Kepler-375 b 1.45 R⊕

Metric	Earth	HD 20794 b	Jupiter
Radius (R⊕)	1.00	1.45	11.21
Mass (M⊕)	1.00	2.70	317.83
Density (g/cm³)	5.51	4.87	1.33
Surface Gravity (g)	1.00	1.28	2.53
Insolation (S⊕)	1.00	—	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Minimum mass (M sin i)	2.150 M⊕	Lower bound from radial-velocity fitting.
Computed mass	2.700 M⊕	Model-computed mass (e.g. from mass-radius relation).

Star Catalogue Identifiers

HD 20794

HIP

HIP 15510

TIC

TIC 301051051

Gaia DR2

Gaia DR2 4847957293277762560

Gaia DR3

Gaia DR3 4847957293278177024

System

HD 20794

Percentile among Super-Earth cohort

Radius 1.450 R⊕ · percentile 28 / cohort 1176

Mass 2.700 M⊕ · percentile 26 / cohort 1176

Orbital period 18.31 d · percentile 83 / cohort 1164

Distance 6.00 pc · percentile 1 / cohort 1171

ESI 0.463 · percentile 69 / cohort 1176

Orbit & Habitability

Orbital Dynamics

Period

18.314 days

Semi-major axis

0.1257 AU

Eccentricity

0.064

Inclination

90.00 °

Year Length

A year here lasts approximately 18.31 Earth days (5.0% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.1257 AU.

Extended Orbital Architecture

RV semi-amplitude (K)

0.614 m/s

Transit mid-time (BJD)

2,460,383.2600

Long. of periastron (ω)

25.00°

Angular separation (arcsec)

20.90000

Eq. Temperature

660K

(387 °C)

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.463

0 = alien, 1 = Earth-identical

Insufficient insolation data — the surface is too hot to retain surface water.

Discovery Paper

Primary reference

Pepe et al. 2011

Instrument

HARPS Spectrograph

Publication

2011-10

Observation locale

Ground

Discovery cohort

Planets confirmed in 2011 at La Silla Observatory (10 shown).

GJ 433 b · Sub-Neptune HD 20794 d · Sub-Neptune HD 192310 b · Neptune-like HD 7449 b · Gas Giant HD 192310 c · Neptune-like HD 217786 b · Gas Giant HIP 5158 c · Gas Giant HD 137388 b · Neptune-like HD 204941 b · Gas Giant HD 7199 b · Unclassified

Host System: HD 20794

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,368 K — cooler than the Sun (5,778 K)

Estimated Age

5.76 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

0.930 R☉

Stellar Mass

0.790 M☉

Metallicity [Fe/H]

-0.42

Extended Stellar Properties

Surface gravity (log g)

4.390 dex

Stellar density

1.704 g/cm³

Systemic radial velocity

87.88 km/s

Rotational v·sin i

3.00 km/s

Activity index (log R'HK)

-4.980

Metallicity ratio

[Fe/H]

Distance

6.00 parsec

Light-years 19.58 ly

V-band magnitude

4.26 mag

Voyager-speed travel 345,266 yr

Multi-band Host Photometry — 8 bands

Astrometric Data

Parallax

166.561 mas

Total Proper Motion

3,120.505 mas/yr

PM Right Ascension

3,033.73 mas/yr

PM Declination

730.78 mas/yr

Galactic Cartesian (pc)

x = 0.470 · y = 0.560 · z = -0.683

Equatorial (J2000)

RA 49.99977° · Dec -43.06665°

Galactic ℓ, b

250.734° · -56.065°

Ecliptic λ, β

27.244° · -58.115°

HTM-20 index

-869587511

Wikipedia → Image: Wikimedia Commons · Eridanus_constellation_map.png: Torsten Bronger derivative work: Kxx (talk) · CC BY-SA 3.0