Key parameters at a glance
- A radius of 11.88 Earth radii
- A mass of 276.51 Earth masses
- Surface gravity around 1.96 g
- An orbital period of 18.248 days
- Semi-major axis 0.1530 AU
- Equilibrium temperature 1,184 K (911 °C)
- Distance from Earth 1,693.50 light-years
- Earth Similarity Index 0.122
- Travel time at Voyager 1 speed 29,864,810 years
1 sibling around K2-99
K2-99 b 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 |
|---|---|---|---|---|---|---|
| K2-99 b this | Gas Giant | 11.88 | 276.51 | 18.248 | 1,184 | 2016 |
| K2-99 c | Gas Giant | 12.60 | 2,669.76 | 522.200 | 390 | 2022 |
K2-99 b Planet Profile
Physical Specs
Classification
Planet Type
Gas Giant
Discovery
Size rank in cohort
Rank by radius
#1551of 1771
top 87.5%
This planet
11.88R⊕
Gas Giant median
13.52R⊕
Nearest-size peers
| Metric | Earth | K2-99 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 11.88 | 11.21 |
| Mass (M⊕) | 1.00 | 276.51 | 317.83 |
| Density (g/cm³) | 5.51 | 0.90 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.96 | 2.53 |
| Insolation (S⊕) | 1.00 | 357.00 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 276.511 M⊕ | Direct mass measurement (not derived). |
Star Catalogue Identifiers
TIC
TIC 176966903
Gaia DR2
Gaia DR2 3620612011248988416
Gaia DR3
Gaia DR3 3620612011248988416
System
K2-99
Percentile among Gas Giant cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 18.25 Earth days (5.0% of a terrestrial year) on a mildly elliptical path at a mean orbital distance of 0.1530 AU.
Transit Fingerprint
Depth
0.193 %
Duration
11.100 h
Impact parameter b
0.340
Rp / R★
0.042600
Transit midpoint (BJD)
2,458,182.7133
Photometric dip
Transit produces a flux drop of 1,930 ppm lasting ≈ 11.10 h.
Extended Orbital Architecture
Planet / star radius ratio
0.042600
Semi-major axis / stellar radius
13.100
Impact parameter (b)
0.340
RV semi-amplitude (K)
54.000 m/s
Transit mid-time (BJD)
2,458,182.7133
Long. of periastron (ω)
334.00°
Angular separation (arcsec)
0.29500
Eq. Temperature
1,184K
(911 °C)
Insolation (S⊕)
357.00
Earth = 1.00
Earth Similarity (ESI)
0.122
0 = alien, 1 = Earth-identical
Inside the inner HZ boundary (too hot for liquid water) — the dayside is scorched.
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
Smith et al. 2017Instrument
Kepler CCD Array
Publication
2017-01
Observation locale
Space
Discovery cohort
Planets confirmed in 2016 at K2 (12 shown).
Host System: K2-99
Spectral Class
G-type yellow (Sun-like)
Effective Temperature
6,069 K — hotter than the Sun (5,778 K)
Estimated Age
3.70 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
2.550 R☉
Stellar Mass
1.440 M☉
Metallicity [Fe/H]
0.20
Extended Stellar Properties
Surface gravity (log g)
3.783 dex
Stellar density
0.078 g/cm³
Systemic radial velocity
-2.86 km/s
Rotational v·sin i
9.30 km/s
Activity index (log R'HK)
-5.393
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 17 bands
Astrometric Data
Parallax
1.898 mas
Total Proper Motion
2.014 mas/yr
PM Right Ascension
-0.32 mas/yr
PM Declination
-1.99 mas/yr
Galactic Cartesian (pc)
x = -0.873 · y = -0.479 · z = -0.095
Equatorial (J2000)
RA 208.77376° · Dec -5.44249°
Galactic ℓ, b
330.586° · 53.976°
Ecliptic λ, β
208.678° · 5.946°
HTM-20 index
247804284
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