Confirmed Exoplanet Discovered 2016

K2-32 c

A sub-neptune orbiting the g-type yellow (sun-like) K2-32, located approximately 514.3 light-years from Earth.

Key parameters at a glance

  • A radius of 3.13 Earth radii
  • A mass of 8.10 Earth masses
  • Surface gravity around 0.82 g
  • An orbital period of 20.661 days
  • Semi-major axis 0.1384 AU
  • Equilibrium temperature 634 K (361 °C)
  • Distance from Earth 514.29 light-years
  • Earth Similarity Index 0.352
  • Travel time at Voyager 1 speed 9,069,491 years

3 siblings around K2-32

K2-32 c shares its host star with 3 other confirmed planets. Side-by-side measurements below.

Planet Type Radius (R⊕) Mass (M⊕) Period (d) Eq. T (K) Year
K2-32 e Rocky Terrestrial 1.21 2.10 4.349 1,066 2019
K2-32 b Neptune-like 5.30 15.00 8.992 837 2016
K2-32 c this Sub-Neptune 3.13 8.10 20.661 634 2016
K2-32 d Sub-Neptune 3.48 6.70 31.717 550 2016

K2-32 c Planet Profile

Physical Specs

Radius
3.13 R⊕
Radius (Jupiter)
0.280 R♃
Mass
8.10 M⊕
Mass (Jupiter)
0.025 M♃
Density
1.43 g/cm³
Surface Gravity
0.82 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.352
HZ Position Inner
Controversial No

Discovery

Year 2016
Method Transit
Facility K2
Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#405of 1978

top 20.4%

This planet

3.13R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Metric Earth K2-32 c Jupiter
Radius (R⊕)1.003.1311.21
Mass (M⊕)1.008.10317.83
Density (g/cm³)5.511.431.33
Surface Gravity (g)1.000.822.53
Insolation (S⊕)1.0026.200.037

Alternative Mass Estimates

Method Value Interpretation
Best measured mass 8.100 M⊕ Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 437444661

Gaia DR2

Gaia DR2 4130539180358512768

Gaia DR3

Gaia DR3 4130539180358512768

System

K2-32

Percentile among Sub-Neptune cohort

Radius 3.134 R⊕ · percentile 80 / cohort 1978
Mass 8.100 M⊕ · percentile 55 / cohort 1978
Orbital period 20.66 d · percentile 63 / cohort 1946
Distance 157.68 pc · percentile 26 / cohort 1975
ESI 0.352 · percentile 41 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period
20.661 days
Semi-major axis
0.1384 AU
Eccentricity
0.049
Inclination
89.40 °

Year Length

A year here lasts approximately 20.66 Earth days (5.7% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.1384 AU.

Transit Fingerprint

Depth

0.135 %

Duration

4.350 h

Impact parameter b

0.370

Rp / R★

0.033420

Transit midpoint (BJD)

2,456,899.4234

Photometric dip

Transit produces a flux drop of 1,346 ppm lasting ≈ 4.35 h.

Extended Orbital Architecture

Planet / star radius ratio

0.033420

Semi-major axis / stellar radius

34.580

Impact parameter (b)

0.370

RV semi-amplitude (K)

2.150 m/s

Transit mid-time (BJD)

2,456,899.4234

Long. of periastron (ω)

168.00°

Angular separation (arcsec)

0.87800

Eq. Temperature

634K

(361 °C)

Insolation (S⊕)

26.20

Earth = 1.00

Earth Similarity (ESI)

0.352

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

Dai et al. 2016

Instrument

Kepler CCD Array

Publication

2016-06

Observation locale

Space

Host System: K2-32

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,271 K — cooler than the Sun (5,778 K)

Estimated Age

7.90 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

0.860 R☉

Stellar Mass

0.830 M☉

Metallicity [Fe/H]

-0.06

Extended Stellar Properties

Surface gravity (log g)

4.490 dex

Stellar density

1.833 g/cm³

Systemic radial velocity

-2.20 km/s

Rotational v·sin i

0.70 km/s

Activity index (log R'HK)

-5.061

Metallicity ratio

[Fe/H]

Distance
157.68 parsec
Light-years 514.29 ly
V-band magnitude
12.30 mag
Voyager-speed travel 9,069,491 yr

Multi-band Host Photometry — 12 bands

8.413.313.27B12.30V12.00Gaia12.01Kepler11.37TESS10.40J9.99H9.82K9.75W19.79W29.89W38.41W4

Astrometric Data

Parallax

6.314 mas

Total Proper Motion

56.149 mas/yr

PM Right Ascension

-16.60 mas/yr

PM Declination

-53.64 mas/yr

Galactic Cartesian (pc)

x = -0.285 · y = -0.898 · z = -0.335

Equatorial (J2000)

RA 252.42601° · Dec -19.54305°

Galactic ℓ, b

0.546° · 15.802°

Ecliptic λ, β

253.443° · 2.892°

HTM-20 index

1677871432

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