Key parameters at a glance

A radius of 1.21 Earth radii
A mass of 10.36 Earth masses
Surface gravity around 7.08 g
An orbital period of 31.828 days
Semi-major axis 0.1869 AU
Equilibrium temperature 686 K (413 °C)
Distance from Earth 2,893.21 light-years
Earth Similarity Index 0.384
Travel time at Voyager 1 speed 51,021,799 years

1 sibling around KOI-3503

KOI-3503 c shares its host star with 1 other confirmed planet. Side-by-side measurements below.

Planet	Type	Radius (R⊕)	Mass (M⊕)	Period (d)	Eq. T (K)	Year
KOI-3503 b	Rocky Terrestrial	1.19	9.20	21.185	785	2021
KOI-3503 c this	Rocky Terrestrial	1.21	10.36	31.828	686	2021

KOI-3503 c Planet Profile

Physical Specs

Radius

1.21 R⊕

Radius (Jupiter)

0.108 R♃

Mass

10.36 M⊕

Mass (Jupiter)

0.033 M♃

Density

10.00 g/cm³

Surface Gravity

7.08 g (Earth)

Classification

Planet Type

Rocky Terrestrial

ESI Score 0.384

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

#56of 570

top 9.6%

This planet

1.21R⊕

Rocky Terrestrial median

1.01R⊕

Nearest-size peers

Kepler-415 b 1.21 R⊕ Kepler-169 c 1.21 R⊕ Kepler-189 b 1.21 R⊕

Metric	Earth	KOI-3503 c	Jupiter
Radius (R⊕)	1.00	1.21	11.21
Mass (M⊕)	1.00	10.36	317.83
Density (g/cm³)	5.51	10.00	1.33
Surface Gravity (g)	1.00	7.08	2.53
Insolation (S⊕)	1.00	52.50	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	10.360 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 138097784

Gaia DR2

Gaia DR2 2077601373302068352

Gaia DR3

Gaia DR3 2077601373302068352

System

KOI-3503

Percentile among Rocky Terrestrial cohort

Radius 1.210 R⊕ · percentile 87 / cohort 570

Mass 10.360 M⊕ · percentile 98 / cohort 570

Orbital period 31.83 d · percentile 97 / cohort 567

Distance 887.06 pc · percentile 90 / cohort 566

ESI 0.384 · percentile 56 / cohort 570

Orbit & Habitability

Orbital Dynamics

Period

31.828 days

Semi-major axis

0.1869 AU

Eccentricity

0.000

Inclination

89.38 °

Year Length

A year here lasts approximately 31.83 Earth days (8.7% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.1869 AU.

Transit Fingerprint

Depth

0.008 %

Duration

4.170 h

Impact parameter b

0.681

Rp / R★

0.008651

Transit midpoint (BJD)

2,454,977.5289

Photometric dip

Transit produces a flux drop of 79 ppm lasting ≈ 4.17 h.

Extended Orbital Architecture

Planet / star radius ratio

0.008651

Semi-major axis / stellar radius

43.400

Impact parameter (b)

0.681

Transit mid-time (BJD)

2,454,977.5289

Angular separation (arcsec)

0.21100

Eq. Temperature

686K

(413 °C)

Insolation (S⊕)

52.50

Earth = 1.00

Earth Similarity (ESI)

0.384

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.

Transit timing variations

Gravitational interactions from neighbours have been detected.

Discovery Paper

Primary reference

Jontof Hutter et al. 2021

Instrument

Kepler CCD Array

Publication

2021-05

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: KOI-3503

Spectral Class

F-type yellow-white

Effective Temperature

6,001 K — hotter than the Sun (5,778 K)

Estimated Age

11.48 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

1.255 R☉

Stellar Mass

0.858 M☉

Metallicity [Fe/H]

-0.54

Extended Stellar Properties

Surface gravity (log g)

4.547 dex

Stellar density

0.440 g/cm³

Metallicity ratio

[M/H]

Distance

887.06 parsec

Light-years 2,893.21 ly

V-band magnitude

13.83 mag

Voyager-speed travel 51,021,799 yr

Multi-band Host Photometry — 16 bands

Astrometric Data

Parallax

1.099 mas

Total Proper Motion

22.085 mas/yr

PM Right Ascension

-9.91 mas/yr

PM Declination

-19.73 mas/yr

Galactic Cartesian (pc)

x = 0.293 · y = -0.686 · z = 0.666

Equatorial (J2000)

RA 293.15077° · Dec 41.72915°

Galactic ℓ, b

74.586° · 10.652°

Ecliptic λ, β

308.805° · 62.085°

HTM-20 index

-184720875