Key parameters at a glance
- A radius of 10.54 Earth radii
- A mass of 460.83 Earth masses
- Surface gravity around 4.15 g
- An orbital period of 86.648 days
- Semi-major axis 0.3820 AU
- Equilibrium temperature 511 K (238 °C)
- Distance from Earth 2,139.58 light-years
- Earth Similarity Index 0.333
- Travel time at Voyager 1 speed 37,731,550 years
KOI-1257 b Planet Profile
Physical Specs
Classification
Planet Type
Gas Giant
Discovery
Size rank in cohort
Rank by radius
#1723of 1771
top 97.2%
This planet
10.54R⊕
Gas Giant median
13.52R⊕
Nearest-size peers
| Metric | Earth | KOI-1257 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 10.54 | 11.21 |
| Mass (M⊕) | 1.00 | 460.83 | 317.83 |
| Density (g/cm³) | 5.51 | 2.10 | 1.33 |
| Surface Gravity (g) | 1.00 | 4.15 | 2.53 |
| Insolation (S⊕) | 1.00 | 7.28 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 460.830 M⊕ | Direct mass measurement (not derived). |
Star Catalogue Identifiers
TIC
TIC 159647910
Gaia DR2
Gaia DR2 2126633166627436928
Gaia DR3
Gaia DR3 2126633166627436928
System
KOI-1257
Percentile among Gas Giant cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 86.65 Earth days (23.7% of a terrestrial year) on a highly eccentric trajectory at a mean orbital distance of 0.3820 AU.
Transit Fingerprint
Depth
0.731 %
Duration
4.262 h
Impact parameter b
0.016
Rp / R★
0.081335
Transit midpoint (BJD)
2,455,006.7945
Photometric dip
Transit produces a flux drop of 7,312 ppm lasting ≈ 4.26 h.
Extended Orbital Architecture
Planet / star radius ratio
0.081335
Semi-major axis / stellar radius
167.911
Impact parameter (b)
0.016
Transit mid-time (BJD)
2,455,006.7945
Long. of periastron (ω)
141.30°
Sky-projected obliquity (λ)
74.00°
Angular separation (arcsec)
0.58200
Eq. Temperature
511K
(238 °C)
Insolation (S⊕)
7.28
Earth = 1.00
Earth Similarity (ESI)
0.333
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.
Radial velocity
Stellar wobble has been measured spectroscopically.
Discovery Paper
Primary reference
Santerne et al. 2014Instrument
Kepler CCD Array
Publication
2014-06
Observation locale
Space
Discovery cohort
Planets confirmed in 2014 at Kepler (12 shown).
Host System: KOI-1257
Spectral Class
G-type yellow (Sun-like)
Effective Temperature
5,520 K — cooler than the Sun (5,778 K)
Estimated Age
9.30 Gyr — older than the Sun (4.6 Gyr)
Stellar Radius
1.130 R☉
Stellar Mass
0.990 M☉
Metallicity [Fe/H]
0.27
Extended Stellar Properties
Surface gravity (log g)
4.320 dex
Stellar density
0.990 g/cm³
Systemic radial velocity
8.80 km/s
Rotational v·sin i
4.60 km/s
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 16 bands
Astrometric Data
Total Proper Motion
16.390 mas/yr
PM Right Ascension
-6.76 mas/yr
PM Declination
-14.93 mas/yr
Galactic Cartesian (pc)
x = 0.256 · y = -0.660 · z = 0.706
Equatorial (J2000)
RA 291.22509° · Dec 44.92729°
Galactic ℓ, b
76.892° · 13.317°
Ecliptic λ, β
308.292° · 65.569°
HTM-20 index
1389743193
Similar Worlds
WASP-56 b
Gas Giant · G-type yellow (Sun-like)
Radius 10.54 R⊕ · 1,047.2 ly
TOI-7510 d
Gas Giant · G-type yellow (Sun-like)
Radius 10.52 R⊕ · 812.1 ly
TOI-1199 b
Gas Giant · G-type yellow (Sun-like)
Radius 10.51 R⊕ · 810.3 ly
WASP-126 b
Gas Giant · G-type yellow (Sun-like)
Radius 10.51 R⊕ · 706.2 ly
TOI-6041 c
Gas Giant · G-type yellow (Sun-like)
Radius 10.50 R⊕ · 236.4 ly
Kepler-685 b
Gas Giant · G-type yellow (Sun-like)
Radius 10.58 R⊕ · 3,061.7 ly