Key parameters at a glance

A radius of 13.50 Earth radii
A mass of 525.69 Earth masses
Surface gravity around 2.88 g
An orbital period of 183.930 days
Semi-major axis 0.6480 AU
Distance from Earth 279.58 light-years
Earth Similarity Index 0.350
Travel time at Voyager 1 speed 4,930,312 years

HD 81688 b Planet Profile

Physical Specs

Radius

13.50 R⊕

Radius (Jupiter)

1.200 R♃

Mass

525.69 M⊕

Mass (Jupiter)

1.654 M♃

Density

1.17 g/cm³

Surface Gravity

2.88 g (Earth)

Classification

Planet Type

Gas Giant

ESI Score 0.350

HZ Position Unknown

Controversial No

Discovery

Year 2007

Method Radial Velocity

Facility Okayama Astrophysical Observatory

Telescope 1.88 m Telescope

Size rank in cohort

Rank by radius

#671of 1771

top 37.8%

This planet

13.50R⊕

Gas Giant median

13.52R⊕

Nearest-size peers

HD 45350 b 13.50 R⊕ HD 82943 b 13.50 R⊕ HD 27442 b 13.50 R⊕

Metric	Earth	HD 81688 b	Jupiter
Radius (R⊕)	1.00	13.50	11.21
Mass (M⊕)	1.00	525.69	317.83
Density (g/cm³)	5.51	1.17	1.33
Surface Gravity (g)	1.00	2.88	2.53
Insolation (S⊕)	1.00	—	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Minimum mass (M sin i)	525.688 M⊕	Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

HD 81688

HIP

HIP 46471

TIC

TIC 105438311

Gaia DR2

Gaia DR2 818464227945910016

Gaia DR3

Gaia DR3 818464227945910016

System

HD 81688

Percentile among Gas Giant cohort

Radius 13.500 R⊕ · percentile 59 / cohort 1771

Mass 525.688 M⊕ · percentile 50 / cohort 1747

Orbital period 183.93 d · percentile 57 / cohort 1533

Distance 85.72 pc · percentile 32 / cohort 1759

ESI 0.350 · percentile 71 / cohort 1771

Orbit & Habitability

Orbital Dynamics

Period

183.930 days

Semi-major axis

0.6480 AU

Eccentricity

0.040

Inclination

— °

Year Length

A year here lasts approximately 183.93 Earth days (50.4% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.6480 AU.

Eq. Temperature

—

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.350

0 = alien, 1 = Earth-identical

Discovery Paper

Primary reference

Sato et al. 2008

Instrument

HIDES Echelle Spectrograph

Publication

2008-06

Observation locale

Ground

Host System: HD 81688

Spectral Class

K-type orange

Effective Temperature

4,797 K — cooler than the Sun (5,778 K)

Estimated Age

1.48 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

11.130 R☉

Stellar Mass

1.070 M☉

Metallicity [Fe/H]

-0.32

Extended Stellar Properties

Surface gravity (log g)

2.370 dex

Systemic radial velocity

38.57 km/s

Rotational v·sin i

1.21 km/s

Metallicity ratio

[Fe/H]

Distance

85.72 parsec

Light-years 279.58 ly

V-band magnitude

5.40 mag

Voyager-speed travel 4,930,312 yr

Multi-band Host Photometry — 16 bands

Astrometric Data

Parallax

11.639 mas

Total Proper Motion

129.787 mas/yr

PM Right Ascension

-7.30 mas/yr

PM Declination

-129.58 mas/yr

Galactic Cartesian (pc)

x = -0.553 · y = 0.429 · z = 0.714

Equatorial (J2000)

RA 142.16658° · Dec 45.60092°

Galactic ℓ, b

174.227° · 46.075°

Ecliptic λ, β

129.179° · 29.001°

HTM-20 index

1217017961

Observation Record

Photometric series

RV measurements

Archive notes

Similar Worlds

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Radius 13.50 R⊕ · 2,534.4 ly

HD 222076 b

Gas Giant · K-type orange

Radius 13.50 R⊕ · 297.3 ly

HD 128311 b

Gas Giant · K-type orange

Radius 13.50 R⊕ · 53.3 ly

BD+48 740 b

Gas Giant · K-type orange

Radius 13.50 R⊕ · 2,174.1 ly

HD 47366 c

Gas Giant · K-type orange

Radius 13.50 R⊕ · 275.1 ly

HD 27442 b

Gas Giant · K-type orange

Radius 13.50 R⊕ · 59.6 ly

Explore Related Categories

Gas Giant Planets Radial Velocity Discoveries Okayama Astrophysical Observatory Mission K-type orange Hosts