Key parameters at a glance

A radius of 1.08 Earth radii
A mass of 1.28 Earth masses
Surface gravity around 1.10 g
An orbital period of 5.577 days
Semi-major axis 0.0400 AU
Distance from Earth 216.67 light-years
Earth Similarity Index 0.980
Travel time at Voyager 1 speed 3,821,015 years
Almost certainly tidally locked to its host star given the close orbit

Context from the literature

K2-72b is a small exoplanet orbiting around the red dwarf star K2-72 approximately 227.7 light-years away. K2-72b completes an orbit in 5.57 days, and it has a radius of only 75% of that of the Earth.

Excerpted from Wikipedia · full article

3 siblings around K2-72

K2-72 b 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
K2-72 b this	Rocky Terrestrial	1.08	1.28	5.577	—	2016
K2-72 d	Rocky Terrestrial	1.01	1.01	7.760	—	2016
K2-72 c	Rocky Terrestrial	1.16	1.65	15.189	—	2016
K2-72 e	Super-Earth	1.29	2.21	24.159	—	2016

K2-72 b Planet Profile

Physical Specs

Radius

1.08 R⊕

Radius (Jupiter)

0.096 R♃

Mass

1.28 M⊕

Mass (Jupiter)

0.004 M♃

Density

5.58 g/cm³

Surface Gravity

1.10 g (Earth)

Classification

Planet Type

Rocky Terrestrial

ESI Score 0.980

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

#253of 570

top 44.2%

This planet

1.08R⊕

Rocky Terrestrial median

1.01R⊕

Nearest-size peers

Wolf 1069 b 1.08 R⊕ Kepler-1605 b 1.08 R⊕ TOI-6255 b 1.08 R⊕

Metric	Earth	K2-72 b	Jupiter
Radius (R⊕)	1.00	1.08	11.21
Mass (M⊕)	1.00	1.28	317.83
Density (g/cm³)	5.51	5.58	1.33
Surface Gravity (g)	1.00	1.10	2.53
Insolation (S⊕)	1.00	8.50	0.037

Star Catalogue Identifiers

TIC

TIC 38337202

Gaia DR2

Gaia DR2 2615653023342995584

Gaia DR3

Gaia DR3 2615653023342995584

System

K2-72

Percentile among Rocky Terrestrial cohort

Radius 1.080 R⊕ · percentile 55 / cohort 570

Mass 1.280 M⊕ · percentile 50 / cohort 570

Orbital period 5.58 d · percentile 58 / cohort 567

Distance 66.43 pc · percentile 20 / cohort 566

ESI 0.980 · percentile 97 / cohort 570

Orbit & Habitability

Orbital Dynamics

Period

5.577 days

Semi-major axis

0.0400 AU

Eccentricity

0.110

Inclination

89.15 °

Year Length

A year here lasts approximately 5.58 Earth days (1.5% of a terrestrial year) on a mildly elliptical path at a mean orbital distance of 0.0400 AU.

Transit Fingerprint

Depth

0.109 %

Duration

1.670 h

Impact parameter b

0.000

Rp / R★

0.029949

Transit midpoint (BJD)

2,457,010.3760

Photometric dip

Transit produces a flux drop of 1,090 ppm lasting ≈ 1.67 h.

Extended Orbital Architecture

Planet / star radius ratio

0.029949

Semi-major axis / stellar radius

24.160

Impact parameter (b)

0.000

Transit mid-time (BJD)

2,457,010.3760

Long. of periastron (ω)

7.49°

Angular separation (arcsec)

0.60200

Eq. Temperature

—

Insolation (S⊕)

8.50

Earth = 1.00

Earth Similarity (ESI)

0.980

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

Crossfield et al. 2016

Instrument

Kepler CCD Array

Publication

2016-09

Observation locale

Space

Discovery cohort

Planets confirmed in 2016 at K2 (12 shown).

K2-72 d · Rocky Terrestrial K2-91 b · Rocky Terrestrial K2-72 c · Rocky Terrestrial K2-102 b · Super-Earth K2-90 c · Super-Earth K2-72 e · Super-Earth K2-83 b · Rocky Terrestrial K2-88 b · Rocky Terrestrial K2-80 c · Super-Earth K2-83 c · Super-Earth K2-65 b · Super-Earth K2-68 b · Super-Earth

Host System: K2-72

Spectral Class

M-type red dwarf

Effective Temperature

3,360 K — cooler than the Sun (5,778 K)

Estimated Age

—

Stellar Radius

0.331 R☉

Stellar Mass

0.271 M☉

Metallicity [Fe/H]

—

Distance

66.43 parsec

Light-years 216.67 ly

V-band magnitude

15.37 mag

Voyager-speed travel 3,821,015 yr

Multi-band Host Photometry — 17 bands

Astrometric Data

Parallax

15.024 mas

Total Proper Motion

209.489 mas/yr

PM Right Ascension

195.86 mas/yr

PM Declination

74.34 mas/yr

Galactic Cartesian (pc)

x = 0.891 · y = -0.423 · z = -0.167

Equatorial (J2000)

RA 334.62275° · Dec -9.61201°

Galactic ℓ, b

51.461° · -49.940°

Ecliptic λ, β

332.985° · 0.853°

HTM-20 index

833098984

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