Key parameters at a glance

A radius of 1.52 Earth radii
A mass of 2.92 Earth masses
Surface gravity around 1.26 g
An orbital period of 2.668 days
Semi-major axis 0.0376 AU
Equilibrium temperature 1,252 K (979 °C)
Distance from Earth 3,607.12 light-years
Earth Similarity Index 0.232
Travel time at Voyager 1 speed 63,611,598 years

Kepler-1257 b Planet Profile

Physical Specs

Radius

1.52 R⊕

Radius (Jupiter)

0.136 R♃

Mass

2.92 M⊕

Mass (Jupiter)

0.009 M♃

Density

4.57 g/cm³

Surface Gravity

1.26 g (Earth)

Classification

Planet Type

Super-Earth

ESI Score 0.232

HZ Position Inner

Controversial No

Discovery

Year 2016

Method Transit

Facility Kepler

Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#707of 1176

top 60.0%

This planet

1.52R⊕

Super-Earth median

1.60R⊕

Nearest-size peers

Kepler-65 d 1.52 R⊕ Kepler-348 b 1.52 R⊕ Kepler-306 b 1.52 R⊕

Metric	Earth	Kepler-1257 b	Jupiter
Radius (R⊕)	1.00	1.52	11.21
Mass (M⊕)	1.00	2.92	317.83
Density (g/cm³)	5.51	4.57	1.33
Surface Gravity (g)	1.00	1.26	2.53
Insolation (S⊕)	1.00	546.91	0.037

Star Catalogue Identifiers

TIC

TIC 272084528

Gaia DR2

Gaia DR2 2079813934296000512

Gaia DR3

Gaia DR3 2079813934296000512

System

Kepler-1257

Percentile among Super-Earth cohort

Radius 1.520 R⊕ · percentile 39 / cohort 1176

Mass 2.920 M⊕ · percentile 36 / cohort 1176

Orbital period 2.67 d · percentile 18 / cohort 1164

Distance 1,105.95 pc · percentile 86 / cohort 1171

ESI 0.232 · percentile 19 / cohort 1176

Orbit & Habitability

Orbital Dynamics

Period

2.668 days

Semi-major axis

0.0376 AU

Eccentricity

0.000

Inclination

87.65 °

Year Length

A year here lasts approximately 2.67 Earth days (0.7% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0376 AU.

Transit Fingerprint

Depth

0.027 %

Duration

2.366 h

Impact parameter b

0.333

Rp / R★

0.015820

Transit midpoint (BJD)

2,454,964.6888

Photometric dip

Transit produces a flux drop of 266 ppm lasting ≈ 2.37 h.

Extended Orbital Architecture

Planet / star radius ratio

0.015820

Semi-major axis / stellar radius

8.390

Impact parameter (b)

0.333

Transit mid-time (BJD)

2,454,964.6888

Angular separation (arcsec)

0.03400

Eq. Temperature

1,252K

(979 °C)

Insolation (S⊕)

546.91

Earth = 1.00

Earth Similarity (ESI)

0.232

0 = alien, 1 = Earth-identical

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

Discovery Paper

Primary reference

Morton et al. 2016

Instrument

Kepler CCD Array

Publication

2016-05

Observation locale

Space

Discovery cohort

Planets confirmed in 2016 at Kepler (12 shown).

Kepler-1512 b · Rocky Terrestrial Kepler-1410 b · Super-Earth Kepler-560 b · Super-Earth Kepler-1389 b · Super-Earth Kepler-1450 b · Super-Earth Kepler-1544 b · Super-Earth Kepler-1459 b · Super-Earth Kepler-1638 b · Super-Earth Kepler-737 b · Super-Earth Kepler-1185 b · Super-Earth Kepler-1178 b · Rocky Terrestrial Kepler-1040 b · Sub-Neptune

Host System: Kepler-1257

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,502 K — cooler than the Sun (5,778 K)

Estimated Age

4.37 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

0.870 R☉

Stellar Mass

0.900 M☉

Metallicity [Fe/H]

-0.09

Extended Stellar Properties

Surface gravity (log g)

4.520 dex

Stellar density

1.424 g/cm³

Metallicity ratio

[Fe/H]

Distance

1,105.95 parsec

Light-years 3,607.12 ly

V-band magnitude

15.64 mag

Voyager-speed travel 63,611,598 yr

Multi-band Host Photometry — 16 bands

Astrometric Data

Parallax

0.877 mas

Total Proper Motion

12.884 mas/yr

PM Right Ascension

-9.40 mas/yr

PM Declination

-8.82 mas/yr

Galactic Cartesian (pc)

x = 0.307 · y = -0.628 · z = 0.715

Equatorial (J2000)

RA 296.07562° · Dec 45.62702°

Galactic ℓ, b

79.097° · 10.582°

Ecliptic λ, β

316.469° · 64.915°

HTM-20 index

-2032381369