Key parameters at a glance

A radius of 6.47 Earth radii
A mass of 34.20 Earth masses
Surface gravity around 0.82 g
An orbital period of 96.045 days
Semi-major axis 0.4610 AU
Distance from Earth 245.39 light-years
Earth Similarity Index 0.406
Travel time at Voyager 1 speed 4,327,412 years

HD 206255 b Planet Profile

Physical Specs

Radius

6.47 R⊕

Radius (Jupiter)

0.577 R♃

Mass

34.20 M⊕

Mass (Jupiter)

0.108 M♃

Density

0.69 g/cm³

Surface Gravity

0.82 g (Earth)

Classification

Planet Type

Neptune-like

ESI Score 0.406

HZ Position Unknown

Controversial No

Discovery

Year 2019

Method Radial Velocity

Facility Las Campanas Observatory

Telescope 6.5 m Magellan II Clay Telescope

Size rank in cohort

Rank by radius

#242of 574

top 42.0%

This planet

6.47R⊕

Neptune-like median

6.39R⊕

Nearest-size peers

TOI-1052 c 6.48 R⊕ KMT-2017-BLG-0165L b 6.45 R⊕ Kepler-603 c 6.50 R⊕

Metric	Earth	HD 206255 b	Jupiter
Radius (R⊕)	1.00	6.47	11.21
Mass (M⊕)	1.00	34.20	317.83
Density (g/cm³)	5.51	0.69	1.33
Surface Gravity (g)	1.00	0.82	2.53
Insolation (S⊕)	1.00	—	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Minimum mass (M sin i)	34.200 M⊕	Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

HD 206255

HIP

HIP 107160

TIC

TIC 139842723

Gaia DR2

Gaia DR2 6561908626047094144

Gaia DR3

Gaia DR3 6561908626047094144

System

HD 206255

Percentile among Neptune-like cohort

Radius 6.470 R⊕ · percentile 58 / cohort 574

Mass 34.200 M⊕ · percentile 56 / cohort 574

Orbital period 96.05 d · percentile 81 / cohort 524

Distance 75.24 pc · percentile 21 / cohort 572

ESI 0.406 · percentile 74 / cohort 574

Orbit & Habitability

Orbital Dynamics

Period

96.045 days

Semi-major axis

0.4610 AU

Eccentricity

0.230

Inclination

— °

Year Length

A year here lasts approximately 96.05 Earth days (26.3% of a terrestrial year) on a mildly elliptical path at a mean orbital distance of 0.4610 AU.

Eq. Temperature

—

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.406

0 = alien, 1 = Earth-identical

Discovery Paper

Primary reference

Feng et al. 2019

Instrument

Carnegie Planet Finder Spectrograph

Publication

2019-06

Observation locale

Ground

Discovery cohort

Planets confirmed in 2019 at Las Campanas Observatory (12 shown).

HD 39855 b · Sub-Neptune HIP 54373 b · Sub-Neptune HD 103949 b · Sub-Neptune HD 24085 b · Sub-Neptune HIP 54373 c · Sub-Neptune HIP 35173 b · Sub-Neptune HD 211970 b · Sub-Neptune HD 64114 b · Neptune-like HIP 71135 b · Neptune-like HD 21411 b · Neptune-like HD 8326 b · Neptune-like HD 102843 b · Gas Giant

Host System: HD 206255

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,635 K — cooler than the Sun (5,778 K)

Estimated Age

—

Stellar Radius

2.221 R☉

Stellar Mass

1.420 M☉

Metallicity [Fe/H]

—

Extended Stellar Properties

Surface gravity (log g)

3.748 dex

Stellar density

0.130 g/cm³

Systemic radial velocity

-3.64 km/s

Rotational v·sin i

2.00 km/s

Activity index (log R'HK)

-5.110

Distance

75.24 parsec

Light-years 245.39 ly

V-band magnitude

7.62 mag

Voyager-speed travel 4,327,412 yr

Multi-band Host Photometry — 11 bands

Astrometric Data

Parallax

13.263 mas

Total Proper Motion

83.209 mas/yr

PM Right Ascension

83.05 mas/yr

PM Declination

5.14 mas/yr

Galactic Cartesian (pc)

x = 0.529 · y = -0.363 · z = -0.767

Equatorial (J2000)

RA 325.59178° · Dec -50.09359°

Galactic ℓ, b

347.154° · -47.495°

Ecliptic λ, β

309.687° · -34.028°

HTM-20 index

-818660061