Key parameters at a glance
- A radius of 2.64 Earth radii
- A mass of 7.46 Earth masses
- Surface gravity around 1.07 g
- An orbital period of 5.392 days
- Semi-major axis 0.0583 AU
- Equilibrium temperature 850 K (577 °C)
- Distance from Earth 3,022.15 light-years
- Earth Similarity Index 0.291
- Travel time at Voyager 1 speed 53,295,700 years
- Almost certainly tidally locked to its host star given the close orbit
Kepler-721 b Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#958of 1978
top 48.4%
This planet
2.64R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | Kepler-721 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 2.64 | 11.21 |
| Mass (M⊕) | 1.00 | 7.46 | 317.83 |
| Density (g/cm³) | 5.51 | 2.23 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.07 | 2.53 |
| Insolation (S⊕) | 1.00 | 138.75 | 0.037 |
Star Catalogue Identifiers
TIC
TIC 164726831
Gaia DR2
Gaia DR2 2106717678151463040
Gaia DR3
Gaia DR3 2106717678151463040
System
Kepler-721
Percentile among Sub-Neptune cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 5.39 Earth days (1.5% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0583 AU.
Transit Fingerprint
Depth
0.115 %
Duration
2.981 h
Impact parameter b
0.790
Rp / R★
0.031472
Transit midpoint (BJD)
2,455,004.7274
Photometric dip
Transit produces a flux drop of 1,151 ppm lasting ≈ 2.98 h.
Extended Orbital Architecture
Planet / star radius ratio
0.031472
Semi-major axis / stellar radius
13.780
Impact parameter (b)
0.790
Transit mid-time (BJD)
2,455,004.7274
Angular separation (arcsec)
0.06290
Eq. Temperature
850K
(577 °C)
Insolation (S⊕)
138.75
Earth = 1.00
Earth Similarity (ESI)
0.291
0 = alien, 1 = Earth-identical
Inside the inner HZ boundary (too hot for liquid water) — the surface is too hot to retain surface water. Close-orbiting tidally-locked around a cool host.
Discovery Paper
Primary reference
Morton et al. 2016Instrument
Kepler CCD Array
Publication
2016-05
Observation locale
Space
Discovery cohort
Planets confirmed in 2016 at Kepler (12 shown).
Host System: Kepler-721
Spectral Class
K-type orange
Effective Temperature
5,075 K — cooler than the Sun (5,778 K)
Estimated Age
4.90 Gyr — older than the Sun (4.6 Gyr)
Stellar Radius
0.780 R☉
Stellar Mass
0.820 M☉
Metallicity [Fe/H]
-0.01
Extended Stellar Properties
Surface gravity (log g)
4.580 dex
Stellar density
1.701 g/cm³
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 16 bands
Astrometric Data
Parallax
1.052 mas
Total Proper Motion
28.069 mas/yr
PM Right Ascension
1.61 mas/yr
PM Declination
-28.02 mas/yr
Galactic Cartesian (pc)
x = 0.178 · y = -0.691 · z = 0.701
Equatorial (J2000)
RA 284.43051° · Dec 44.48038°
Galactic ℓ, b
74.499° · 17.583°
Ecliptic λ, β
296.584° · 66.593°
HTM-20 index
962704569
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