Confirmed Exoplanet Discovered 2017

K2-115 b

A gas giant orbiting the g-type yellow (sun-like) K2-115, located approximately 1,349.0 light-years from Earth.

Key parameters at a glance

  • A radius of 11.80 Earth radii
  • A mass of 321.01 Earth masses
  • Surface gravity around 2.30 g
  • An orbital period of 20.273 days
  • Semi-major axis 0.1415 AU
  • Equilibrium temperature 696 K (423 °C)
  • Distance from Earth 1,348.95 light-years
  • Earth Similarity Index 0.221
  • Travel time at Voyager 1 speed 23,788,765 years

K2-115 b Planet Profile

Physical Specs

Radius
11.80 R⊕
Radius (Jupiter)
1.053 R♃
Mass
321.01 M⊕
Mass (Jupiter)
1.010 M♃
Density
1.07 g/cm³
Surface Gravity
2.30 g (Earth)

Classification

Planet Type

Gas Giant

ESI Score 0.221
HZ Position Inner
Controversial No

Discovery

Year 2017
Method Transit
Facility K2
Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#1558of 1771

top 87.9%

This planet

11.80R⊕

Gas Giant median

13.52R⊕

Nearest-size peers

Metric Earth K2-115 b Jupiter
Radius (R⊕)1.0011.8011.21
Mass (M⊕)1.00321.01317.83
Density (g/cm³)5.511.071.33
Surface Gravity (g)1.002.302.53
Insolation (S⊕)1.0020.440.037

Alternative Mass Estimates

Method Value Interpretation
Best measured mass 321.007 M⊕ Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 7020254

Gaia DR2

Gaia DR2 650778499868023296

Gaia DR3

Gaia DR3 650778499868023296

System

K2-115

Percentile among Gas Giant cohort

Radius 11.803 R⊕ · percentile 12 / cohort 1771
Mass 321.007 M⊕ · percentile 35 / cohort 1747
Orbital period 20.27 d · percentile 47 / cohort 1533
Distance 413.59 pc · percentile 71 / cohort 1759
ESI 0.221 · percentile 41 / cohort 1771

Orbit & Habitability

Orbital Dynamics

Period
20.273 days
Semi-major axis
0.1415 AU
Eccentricity
0.063
Inclination
88.91 °

Year Length

A year here lasts approximately 20.27 Earth days (5.6% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.1415 AU.

Transit Fingerprint

Depth

1.603 %

Duration

3.874 h

Impact parameter b

0.655

Rp / R★

0.126590

Transit midpoint (BJD)

2,457,522.0701

Photometric dip

Transit produces a flux drop of 16,030 ppm lasting ≈ 3.87 h.

Extended Orbital Architecture

Planet / star radius ratio

0.126590

Semi-major axis / stellar radius

35.620

Impact parameter (b)

0.655

RV semi-amplitude (K)

80.000 m/s

Transit mid-time (BJD)

2,457,522.0701

Long. of periastron (ω)

137.00°

Angular separation (arcsec)

0.34200

Eq. Temperature

696K

(423 °C)

Insolation (S⊕)

20.44

Earth = 1.00

Earth Similarity (ESI)

0.221

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — the surface is too hot to retain surface water.

Detection Signatures

Transit photometry

A transit dip has been observed from at least one telescope.

Radial velocity

Stellar wobble has been measured spectroscopically.

Discovery Paper

Primary reference

Shporer et al. 2017

Instrument

Kepler CCD Array

Publication

2017-11

Observation locale

Space

Host System: K2-115

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,870 K — hotter than the Sun (5,778 K)

Estimated Age

2.20 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

0.855 R☉

Stellar Mass

0.918 M☉

Metallicity [Fe/H]

-0.20

Extended Stellar Properties

Surface gravity (log g)

4.538 dex

Stellar density

2.080 g/cm³

Metallicity ratio

[Fe/H]

Distance
413.59 parsec
Light-years 1,348.95 ly
V-band magnitude
13.44 mag
Voyager-speed travel 23,788,765 yr

Multi-band Host Photometry — 17 bands

8.615.415.42U14.01B13.44V13.20Gaia13.19Kepler12.75TESS13.84Sloan g13.23Sloan r13.20Sloan i13.38Sloan z12.11J11.76H11.72K11.66W111.70W211.72W38.57W4

Astrometric Data

Parallax

2.389 mas

Total Proper Motion

26.677 mas/yr

PM Right Ascension

15.56 mas/yr

PM Declination

-21.67 mas/yr

Galactic Cartesian (pc)

x = -0.582 · y = 0.785 · z = 0.213

Equatorial (J2000)

RA 126.55350° · Dec 12.28185°

Galactic ℓ, b

212.274° · 26.517°

Ecliptic λ, β

125.868° · -6.722°

HTM-20 index

7041805

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