Confirmed Exoplanet Discovered 2018

K2-148 c

A super-earth orbiting the k-type orange K2-148, located approximately 405.9 light-years from Earth.

Key parameters at a glance

  • A radius of 1.73 Earth radii
  • A mass of 3.64 Earth masses
  • Surface gravity around 1.22 g
  • An orbital period of 6.923 days
  • Semi-major axis 0.0616 AU
  • Distance from Earth 405.93 light-years
  • Earth Similarity Index 0.839
  • Travel time at Voyager 1 speed 7,158,526 years
  • Almost certainly tidally locked to its host star given the close orbit

2 siblings around K2-148

K2-148 c 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
K2-148 b Super-Earth 1.33 2.33 4.384 2018
K2-148 c this Super-Earth 1.73 3.64 6.923 2018
K2-148 d Super-Earth 1.64 3.33 9.758 2018

K2-148 c Planet Profile

Physical Specs

Radius
1.73 R⊕
Radius (Jupiter)
0.154 R♃
Mass
3.64 M⊕
Mass (Jupiter)
0.012 M♃
Density
3.86 g/cm³
Surface Gravity
1.22 g (Earth)

Classification

Planet Type

Super-Earth

ESI Score 0.839
HZ Position Inner
Controversial No

Discovery

Year 2018
Method Transit
Facility K2
Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#356of 1176

top 30.2%

This planet

1.73R⊕

Super-Earth median

1.60R⊕

Nearest-size peers

Metric Earth K2-148 c Jupiter
Radius (R⊕)1.001.7311.21
Mass (M⊕)1.003.64317.83
Density (g/cm³)5.513.861.33
Surface Gravity (g)1.001.222.53
Insolation (S⊕)1.0026.500.037

Star Catalogue Identifiers

TIC

TIC 423358488

Gaia DR2

Gaia DR2 2536443724641751808

Gaia DR3

Gaia DR3 2536443724641751808

System

K2-148

Percentile among Super-Earth cohort

Radius 1.730 R⊕ · percentile 68 / cohort 1176
Mass 3.640 M⊕ · percentile 62 / cohort 1176
Orbital period 6.92 d · percentile 51 / cohort 1164
Distance 124.46 pc · percentile 19 / cohort 1171
ESI 0.839 · percentile 92 / cohort 1176

Orbit & Habitability

Orbital Dynamics

Period
6.923 days
Semi-major axis
0.0616 AU
Eccentricity
Inclination
°

Year Length

A year here lasts approximately 6.92 Earth days (1.9% of a terrestrial year) at a mean orbital distance of 0.0616 AU.

Transit Fingerprint

Depth

0.054 %

Duration

2.030 h

Rp / R★

0.025100

Transit midpoint (BJD)

2,457,387.7278

Photometric dip

Transit produces a flux drop of 537 ppm lasting ≈ 2.03 h.

Extended Orbital Architecture

Planet / star radius ratio

0.025100

Semi-major axis / stellar radius

27.300

Transit mid-time (BJD)

2,457,387.7278

Angular separation (arcsec)

0.49500

Eq. Temperature

 

Insolation (S⊕)

26.50

Earth = 1.00

Earth Similarity (ESI)

0.839

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water). Close-orbiting tidally-locked around a cool host.

Discovery Paper

Primary reference

Hirano et al. 2018

Instrument

Kepler CCD Array

Publication

2018-03

Observation locale

Space

Host System: K2-148

Spectral Class

K-type orange

Effective Temperature

4,079 K — cooler than the Sun (5,778 K)

Estimated Age

Stellar Radius

0.632 R☉

Stellar Mass

0.650 M☉

Metallicity [Fe/H]

-0.11

Extended Stellar Properties

Surface gravity (log g)

4.653 dex

Stellar density

2.943 g/cm³

Systemic radial velocity

1.52 km/s

Metallicity ratio

[Fe/H]

Distance
124.46 parsec
Light-years 405.93 ly
V-band magnitude
13.63 mag
Voyager-speed travel 7,158,526 yr

Multi-band Host Photometry — 12 bands

8.414.914.90B13.63V13.06Gaia12.98Kepler12.25TESS11.08J10.46H10.29K10.21W110.26W210.16W38.44W4

Astrometric Data

Parallax

8.006 mas

Total Proper Motion

45.323 mas/yr

PM Right Ascension

-38.70 mas/yr

PM Declination

-23.59 mas/yr

Galactic Cartesian (pc)

x = 0.968 · y = 0.251 · z = -0.003

Equatorial (J2000)

RA 14.51765° · Dec -0.19326°

Galactic ℓ, b

126.589° · -63.018°

Ecliptic λ, β

13.285° · -5.901°

HTM-20 index

-1835770589

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