Key parameters at a glance

A radius of 2.61 Earth radii
A mass of 7.31 Earth masses
Surface gravity around 1.07 g
An orbital period of 2.522 days
Semi-major axis 0.0380 AU
Distance from Earth 180.97 light-years
Earth Similarity Index 0.689
Travel time at Voyager 1 speed 3,191,347 years

1 sibling around HD 217786

HD 217786 c shares its host star with 1 other confirmed planet. Side-by-side measurements below.

Planet	Type	Radius (R⊕)	Mass (M⊕)	Period (d)	Eq. T (K)	Year
HD 217786 c this	Sub-Neptune	2.61	7.31	2.522	—	2022
HD 217786 b	Gas Giant	12.30	4,402.56	1,301.360	—	2011

HD 217786 c Planet Profile

Physical Specs

Radius

2.61 R⊕

Radius (Jupiter)

0.233 R♃

Mass

7.31 M⊕

Mass (Jupiter)

0.023 M♃

Density

2.26 g/cm³

Surface Gravity

1.07 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.689

HZ Position Unknown

Controversial No

Discovery

Year 2022

Method Radial Velocity

Facility Multiple Observatories

Telescope Multiple Telescopes

Size rank in cohort

Rank by radius

#999of 1978

top 50.5%

This planet

2.61R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-214 b 2.61 R⊕ GJ 143 b 2.61 R⊕ TOI-1422 c 2.61 R⊕

Metric	Earth	HD 217786 c	Jupiter
Radius (R⊕)	1.00	2.61	11.21
Mass (M⊕)	1.00	7.31	317.83
Density (g/cm³)	5.51	2.26	1.33
Surface Gravity (g)	1.00	1.07	2.53
Insolation (S⊕)	1.00	—	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Minimum mass (M sin i)	7.310 M⊕	Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

HD 217786

HIP

HIP 113834

TIC

TIC 248048656

Gaia DR2

Gaia DR2 2650902026099857920

Gaia DR3

Gaia DR3 2650902026099857920

System

HD 217786

Percentile among Sub-Neptune cohort

Radius 2.610 R⊕ · percentile 49 / cohort 1978

Mass 7.310 M⊕ · percentile 45 / cohort 1978

Orbital period 2.52 d · percentile 3 / cohort 1946

Distance 55.48 pc · percentile 12 / cohort 1975

ESI 0.689 · percentile 91 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

2.522 days

Semi-major axis

0.0380 AU

Eccentricity

0.399

Inclination

— °

Year Length

A year here lasts approximately 2.52 Earth days (0.7% of a terrestrial year) on a highly eccentric trajectory at a mean orbital distance of 0.0380 AU.

Eq. Temperature

—

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.689

0 = alien, 1 = Earth-identical

Discovery Paper

Primary reference

Feng et al. 2022

Instrument

Multiple Instruments

Publication

2022-09

Observation locale

Ground

Discovery cohort

Planets confirmed in 2022 at Multiple Observatories (12 shown).

Kepler-138 e · Rocky Terrestrial HD 93351 b · Super-Earth GJ 1002 b · Rocky Terrestrial GJ 2030 b · Sub-Neptune GJ 3929 c · Sub-Neptune GJ 1002 c · Rocky Terrestrial HD 155918 b · Sub-Neptune HD 213519 b · Sub-Neptune HD 191939 g · Sub-Neptune GJ 514 b · Sub-Neptune HD 12235 b · Sub-Neptune HD 18143 b · Sub-Neptune

Host System: HD 217786

Spectral Class

F-type yellow-white

Effective Temperature

5,966 K — hotter than the Sun (5,778 K)

Estimated Age

7.60 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

1.270 R☉

Stellar Mass

1.140 M☉

Metallicity [Fe/H]

-0.14

Extended Stellar Properties

Surface gravity (log g)

4.350 dex

Stellar density

0.776 g/cm³

Systemic radial velocity

9.98 km/s

Rotational v·sin i

1.40 km/s

Metallicity ratio

[Fe/H]

Distance

55.48 parsec

Light-years 180.97 ly

V-band magnitude

7.78 mag

Voyager-speed travel 3,191,347 yr

Multi-band Host Photometry — 11 bands

Astrometric Data

Parallax

17.995 mas

Total Proper Motion

191.246 mas/yr

PM Right Ascension

-89.93 mas/yr

PM Declination

-168.78 mas/yr

Galactic Cartesian (pc)

x = 0.969 · y = -0.246 · z = -0.008

Equatorial (J2000)

RA 345.78381° · Dec -0.43036°

Galactic ℓ, b

74.193° · -52.736°

Ecliptic λ, β

346.744° · 5.209°

HTM-20 index

1657565510