Key parameters at a glance

A radius of 14.00 Earth radii
A mass of 127.13 Earth masses
Surface gravity around 0.65 g
An orbital period of 956.000 days
Semi-major axis 1.8500 AU
Distance from Earth 196.36 light-years
Earth Similarity Index 0.244
Travel time at Voyager 1 speed 3,462,825 years

HD 181720 b Planet Profile

Physical Specs

Radius

14.00 R⊕

Radius (Jupiter)

1.250 R♃

Mass

127.13 M⊕

Mass (Jupiter)

0.400 M♃

Density

0.26 g/cm³

Surface Gravity

0.65 g (Earth)

Classification

Planet Type

Gas Giant

ESI Score 0.244

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

#415of 1771

top 23.4%

This planet

14.00R⊕

Gas Giant median

13.52R⊕

Nearest-size peers

HD 9446 b 14.00 R⊕ HD 156411 b 14.00 R⊕ HD 224693 b 14.00 R⊕

Metric	Earth	HD 181720 b	Jupiter
Radius (R⊕)	1.00	14.00	11.21
Mass (M⊕)	1.00	127.13	317.83
Density (g/cm³)	5.51	0.26	1.33
Surface Gravity (g)	1.00	0.65	2.53
Insolation (S⊕)	1.00	—	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Minimum mass (M sin i)	127.132 M⊕	Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

HD 181720

HIP

HIP 95262

TIC

TIC 112243062

Gaia DR2

Gaia DR2 6745589980571162752

Gaia DR3

Gaia DR3 6745589980571162752

System

HD 181720

Percentile among Gas Giant cohort

Radius 14.000 R⊕ · percentile 74 / cohort 1771

Mass 127.132 M⊕ · percentile 9 / cohort 1747

Orbital period 956.00 d · percentile 76 / cohort 1533

Distance 60.20 pc · percentile 25 / cohort 1759

ESI 0.244 · percentile 42 / cohort 1771

Orbit & Habitability

Orbital Dynamics

Period

956.000 days

Semi-major axis

1.8500 AU

Eccentricity

0.260

Inclination

— °

Year Length

A year here lasts about 2.62 Earth years on a mildly elliptical path at a mean orbital distance of 1.8500 AU.

Eq. Temperature

—

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.244

0 = alien, 1 = Earth-identical

Discovery Paper

Primary reference

Santos et al. 2010

Instrument

HARPS Spectrograph

Publication

2010-03

Observation locale

Ground

Discovery cohort

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

GJ 581 e · Super-Earth 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

Host System: HD 181720

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,736 K — cooler than the Sun (5,778 K)

Estimated Age

—

Stellar Radius

1.500 R☉

Stellar Mass

1.030 M☉

Metallicity [Fe/H]

-0.62

Extended Stellar Properties

Surface gravity (log g)

4.090 dex

Stellar density

0.427 g/cm³

Systemic radial velocity

-45.34 km/s

Rotational v·sin i

1.50 km/s

Activity index (log R'HK)

-5.070

Metallicity ratio

[Fe/H]

Distance

60.20 parsec

Light-years 196.36 ly

V-band magnitude

7.84 mag

Voyager-speed travel 3,462,825 yr

Multi-band Host Photometry — 11 bands

Astrometric Data

Parallax

16.582 mas

Total Proper Motion

424.297 mas/yr

PM Right Ascension

88.15 mas/yr

PM Declination

-415.04 mas/yr

Galactic Cartesian (pc)

x = 0.297 · y = -0.785 · z = -0.543

Equatorial (J2000)

RA 290.72122° · Dec -32.92084°

Galactic ℓ, b

5.515° · -20.488°

Ecliptic λ, β

287.592° · -10.739°

HTM-20 index

-1421662484