Confirmed Exoplanet Discovered 2015

K2-19 b

A neptune-like orbiting the g-type yellow (sun-like) K2-19, located approximately 945.3 light-years from Earth.

Key parameters at a glance

  • A radius of 6.59 Earth radii
  • A mass of 30.80 Earth masses
  • Surface gravity around 0.71 g
  • An orbital period of 7.923 days
  • Semi-major axis 0.0749 AU
  • Equilibrium temperature 857 K (584 °C)
  • Distance from Earth 945.29 light-years
  • Earth Similarity Index 0.189
  • Travel time at Voyager 1 speed 16,670,156 years

2 siblings around K2-19

K2-19 b shares its host star with 2 other confirmed planets. Side-by-side measurements below.

Planet Type Radius (R⊕) Mass (M⊕) Period (d) Eq. T (K) Year
K2-19 d Rocky Terrestrial 1.04 6.20 2.508 1,258 2016
K2-19 b this Neptune-like 6.59 30.80 7.923 857 2015
K2-19 c Sub-Neptune 3.88 11.12 11.898 749 2015

K2-19 b Planet Profile

Physical Specs

Radius
6.59 R⊕
Radius (Jupiter)
0.588 R♃
Mass
30.80 M⊕
Mass (Jupiter)
0.097 M♃
Density
0.59 g/cm³
Surface Gravity
0.71 g (Earth)

Classification

Planet Type

Neptune-like

ESI Score 0.189
HZ Position Inner
Controversial No

Discovery

Year 2015
Method Transit
Facility K2
Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#231of 574

top 40.1%

This planet

6.59R⊕

Neptune-like median

6.39R⊕

Nearest-size peers

Metric Earth K2-19 b Jupiter
Radius (R⊕)1.006.5911.21
Mass (M⊕)1.0030.80317.83
Density (g/cm³)5.510.591.33
Surface Gravity (g)1.000.712.53
Insolation (S⊕)1.0087.000.037

Alternative Mass Estimates

Method Value Interpretation
Best measured mass 30.800 M⊕ Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 281885301

Gaia DR2

Gaia DR2 3798833775141351552

Gaia DR3

Gaia DR3 3798833775141351552

System

K2-19

Percentile among Neptune-like cohort

Radius 6.590 R⊕ · percentile 60 / cohort 574
Mass 30.800 M⊕ · percentile 51 / cohort 574
Orbital period 7.92 d · percentile 31 / cohort 524
Distance 289.83 pc · percentile 47 / cohort 572
ESI 0.189 · percentile 25 / cohort 574

Orbit & Habitability

Orbital Dynamics

Period
7.923 days
Semi-major axis
0.0749 AU
Eccentricity
0.043
Inclination
89.37 °

Year Length

A year here lasts approximately 7.92 Earth days (2.2% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0749 AU.

Transit Fingerprint

Depth

0.667 %

Duration

3.237 h

Impact parameter b

0.217

Rp / R★

0.073320

Transit midpoint (BJD)

2,456,829.2223

Photometric dip

Transit produces a flux drop of 6,673 ppm lasting ≈ 3.24 h.

Extended Orbital Architecture

Planet / star radius ratio

0.073320

Semi-major axis / stellar radius

19.530

Impact parameter (b)

0.217

RV semi-amplitude (K)

10.660 m/s

Transit mid-time (BJD)

2,456,829.2223

Long. of periastron (ω)

197.00°

Angular separation (arcsec)

0.25800

Eq. Temperature

857K

(584 °C)

Insolation (S⊕)

87.00

Earth = 1.00

Earth Similarity (ESI)

0.189

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.

Transit timing variations

Gravitational interactions from neighbours have been detected.

Discovery Paper

Primary reference

Dai et al. 2016

Instrument

Kepler CCD Array

Publication

2016-06

Observation locale

Space

Host System: K2-19

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,350 K — cooler than the Sun (5,778 K)

Estimated Age

1.70 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

0.824 R☉

Stellar Mass

0.892 M☉

Metallicity [Fe/H]

0.03

Extended Stellar Properties

Surface gravity (log g)

4.556 dex

Stellar density

1.590 g/cm³

Systemic radial velocity

7.31 km/s

Rotational v·sin i

3.00 km/s

Rotation period

18.36 days

Metallicity ratio

[Fe/H]

Distance
289.83 parsec
Light-years 945.29 ly
V-band magnitude
13.02 mag
Voyager-speed travel 16,670,156 yr

Multi-band Host Photometry — 17 bands

9.015.915.86U13.80B13.02V12.82Gaia12.81Kepler12.30TESS13.82Sloan g12.84Sloan r12.75Sloan i13.90Sloan z11.60J11.21H11.16K11.11W111.15W210.92W38.98W4

Astrometric Data

Parallax

3.423 mas

Total Proper Motion

19.300 mas/yr

PM Right Ascension

-18.79 mas/yr

PM Declination

4.42 mas/yr

Galactic Cartesian (pc)

x = -0.996 · y = 0.088 · z = 0.011

Equatorial (J2000)

RA 174.96025° · Dec 0.60360°

Galactic ℓ, b

267.029° · 58.394°

Ecliptic λ, β

175.131° · -1.448°

HTM-20 index

1093139326

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