Confirmed Exoplanet Discovered 2018

GJ 317 c

A gas giant orbiting the m-type red dwarf GJ 317, located approximately 49.6 light-years from Earth.

Key parameters at a glance

  • A radius of 13.60 Earth radii
  • A mass of 454.49 Earth masses
  • Surface gravity around 2.46 g
  • An orbital period of 6,500.000 days
  • Semi-major axis 5.0400 AU
  • Distance from Earth 49.57 light-years
  • Earth Similarity Index 0.338
  • Travel time at Voyager 1 speed 874,084 years

1 sibling around GJ 317

GJ 317 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
GJ 317 b Gas Giant 13.30 794.50 695.690 2007
GJ 317 c this Gas Giant 13.60 454.49 6,500.000 2018

GJ 317 c Planet Profile

Physical Specs

Radius
13.60 R⊕
Radius (Jupiter)
1.210 R♃
Mass
454.49 M⊕
Mass (Jupiter)
1.430 M♃
Density
0.99 g/cm³
Surface Gravity
2.46 g (Earth)

Classification

Planet Type

Gas Giant

ESI Score 0.338
HZ Position Unknown
Controversial No

Discovery

Year 2018
Method Radial Velocity
Facility W. M. Keck Observatory
Telescope 10 m Keck I Telescope

Size rank in cohort

Rank by radius

#609of 1771

top 34.3%

This planet

13.60R⊕

Gas Giant median

13.52R⊕

Nearest-size peers

Metric Earth GJ 317 c Jupiter
Radius (R⊕)1.0013.6011.21
Mass (M⊕)1.00454.49317.83
Density (g/cm³)5.510.991.33
Surface Gravity (g)1.002.462.53
Insolation (S⊕)1.000.037

Alternative Mass Estimates

Method Value Interpretation
Minimum mass (M sin i) 454.495 M⊕ Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

TIC

TIC 118608254

Gaia DR2

Gaia DR2 5701750711020088192

Gaia DR3

Gaia DR3 5701750715316821248

System

GJ 317

Percentile among Gas Giant cohort

Radius 13.600 R⊕ · percentile 63 / cohort 1771
Mass 454.495 M⊕ · percentile 46 / cohort 1747
Orbital period 6,500.00 d · percentile 94 / cohort 1533
Distance 15.20 pc · percentile 2 / cohort 1759
ESI 0.338 · percentile 67 / cohort 1771

Orbit & Habitability

Orbital Dynamics

Period
6,500.000 days
Semi-major axis
5.0400 AU
Eccentricity
0.217
Inclination
°

Year Length

A year here lasts about 17.80 Earth years on a mildly elliptical path at a mean orbital distance of 5.0400 AU.

Extended Orbital Architecture

RV semi-amplitude (K)

29.330 m/s

Transit mid-time (BJD)

2,462,735.0000

Long. of periastron (ω)

106.70°

Angular separation (arcsec)

332.00000

Eq. Temperature

 

Insolation (S⊕)

Earth = 1.00

Earth Similarity (ESI)

0.338

0 = alien, 1 = Earth-identical

Discovery Paper

Primary reference

Bryan et al. 2016

Instrument

HIRES Spectrometer

Publication

2016-04

Observation locale

Ground

Host System: GJ 317

Spectral Class

M-type red dwarf

Effective Temperature

3,496 K — cooler than the Sun (5,778 K)

Estimated Age

5.00 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

0.403 R☉

Stellar Mass

0.402 M☉

Metallicity [Fe/H]

-0.02

Extended Stellar Properties

Surface gravity (log g)

4.822 dex

Stellar density

7.648 g/cm³

Systemic radial velocity

87.80 km/s

Rotational v·sin i

2.50 km/s

Rotation period

57.50 days

Metallicity ratio

[Fe/H]

Distance
15.20 parsec
Light-years 49.57 ly
V-band magnitude
12.40 mag
Voyager-speed travel 874,084 yr

Multi-band Host Photometry — 12 bands

6.513.513.47B12.40V10.75Gaia9.51TESS9.37Ic7.93J7.32H7.03K6.87W16.77W26.70W36.50W4

Astrometric Data

Parallax

65.774 mas

Total Proper Motion

928.232 mas/yr

PM Right Ascension

-461.16 mas/yr

PM Declination

805.57 mas/yr

Galactic Cartesian (pc)

x = -0.593 · y = 0.700 · z = -0.398

Equatorial (J2000)

RA 130.24453° · Dec -23.45281°

Galactic ℓ, b

246.795° · 11.190°

Ecliptic λ, β

140.752° · -40.068°

HTM-20 index

-115598586

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