Key parameters at a glance

A radius of 2.92 Earth radii
A mass of 8.86 Earth masses
Surface gravity around 1.04 g
An orbital period of 4.446 days
Semi-major axis 0.0521 AU
Equilibrium temperature 1,063 K (790 °C)
Distance from Earth 4,873.75 light-years
Earth Similarity Index 0.220
Travel time at Voyager 1 speed 85,948,561 years

Kepler-1878 b Planet Profile

Physical Specs

Radius

2.92 R⊕

Radius (Jupiter)

0.261 R♃

Mass

8.86 M⊕

Mass (Jupiter)

0.028 M♃

Density

1.96 g/cm³

Surface Gravity

1.04 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.220

HZ Position Inner

Controversial No

Discovery

Year 2021

Method Transit

Facility Kepler

Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#599of 1978

top 30.2%

This planet

2.92R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-1475 b 2.92 R⊕ Kepler-153 b 2.92 R⊕ Kepler-769 b 2.92 R⊕

Metric	Earth	Kepler-1878 b	Jupiter
Radius (R⊕)	1.00	2.92	11.21
Mass (M⊕)	1.00	8.86	317.83
Density (g/cm³)	5.51	1.96	1.33
Surface Gravity (g)	1.00	1.04	2.53
Insolation (S⊕)	1.00	302.60	0.037

Star Catalogue Identifiers

TIC

TIC 184998205

Gaia DR2

Gaia DR2 2076067073548982784

Gaia DR3

Gaia DR3 2076067073548982784

System

Kepler-1878

Percentile among Sub-Neptune cohort

Radius 2.920 R⊕ · percentile 70 / cohort 1978

Mass 8.860 M⊕ · percentile 64 / cohort 1978

Orbital period 4.45 d · percentile 10 / cohort 1946

Distance 1,494.30 pc · percentile 93 / cohort 1975

ESI 0.220 · percentile 10 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

4.446 days

Semi-major axis

0.0521 AU

Eccentricity

0.000

Inclination

86.18 °

Year Length

A year here lasts approximately 4.45 Earth days (1.2% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0521 AU.

Transit Fingerprint

Depth

0.044 %

Duration

2.382 h

Impact parameter b

0.650

Rp / R★

0.020568

Transit midpoint (BJD)

2,454,964.7431

Photometric dip

Transit produces a flux drop of 441 ppm lasting ≈ 2.38 h.

Extended Orbital Architecture

Planet / star radius ratio

0.020568

Semi-major axis / stellar radius

10.570

Impact parameter (b)

0.650

Transit mid-time (BJD)

2,454,964.7431

Angular separation (arcsec)

0.03490

Eq. Temperature

1,063K

(790 °C)

Insolation (S⊕)

302.60

Earth = 1.00

Earth Similarity (ESI)

0.220

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — the dayside is scorched.

Discovery Paper

Primary reference

Valizadegan et al. 2022

Instrument

Kepler CCD Array

Publication

2022-02

Observation locale

Space

Discovery cohort

Planets confirmed in 2021 at Kepler (12 shown).

Kepler-1816 b · Super-Earth Kepler-1705 c · Sub-Neptune Kepler-1948 b · Rocky Terrestrial Kepler-196 d · Sub-Neptune Kepler-1853 b · Super-Earth Kepler-1840 b · Sub-Neptune Kepler-1881 b · Sub-Neptune Kepler-1858 b · Sub-Neptune Kepler-1874 b · Sub-Neptune Kepler-1802 c · Sub-Neptune Kepler-1749 b · Super-Earth Kepler-1849 b · Sub-Neptune

Host System: Kepler-1878

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,918 K — hotter than the Sun (5,778 K)

Estimated Age

—

Stellar Radius

0.865 R☉

Stellar Mass

0.956 M☉

Metallicity [Fe/H]

-0.26

Extended Stellar Properties

Surface gravity (log g)

4.544 dex

Stellar density

1.131 g/cm³

Metallicity ratio

[Fe/H]

Distance

1,494.30 parsec

Light-years 4,873.75 ly

V-band magnitude

15.59 mag

Voyager-speed travel 85,948,561 yr

Multi-band Host Photometry — 16 bands

Astrometric Data

Parallax

0.641 mas

Total Proper Motion

7.712 mas/yr

PM Right Ascension

2.42 mas/yr

PM Declination

-7.32 mas/yr

Galactic Cartesian (pc)

x = 0.367 · y = -0.617 · z = 0.696

Equatorial (J2000)

RA 300.73242° · Dec 44.10702°

Galactic ℓ, b

79.423° · 6.963°

Ecliptic λ, β

321.732° · 62.138°

HTM-20 index

-1612068547