Key parameters at a glance
- A radius of 1.44 Earth radii
- A mass of 4.28 Earth masses
- Surface gravity around 2.06 g
- An orbital period of 1.209 days
- Semi-major axis 0.0189 AU
- Equilibrium temperature 1,035 K (762 °C)
- Distance from Earth 96.74 light-years
- Earth Similarity Index 0.274
- Travel time at Voyager 1 speed 1,706,030 years
- Almost certainly tidally locked to its host star given the close orbit
2 siblings around GJ 9827
GJ 9827 b shares its host star with 2 other confirmed planets. Side-by-side measurements below.
GJ 9827 b Planet Profile
Physical Specs
Classification
Planet Type
Super-Earth
Discovery
Size rank in cohort
Rank by radius
#850of 1176
top 72.2%
This planet
1.44R⊕
Super-Earth median
1.60R⊕
Nearest-size peers
| Metric | Earth | GJ 9827 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 1.44 | 11.21 |
| Mass (M⊕) | 1.00 | 4.28 | 317.83 |
| Density (g/cm³) | 5.51 | 7.86 | 1.33 |
| Surface Gravity (g) | 1.00 | 2.06 | 2.53 |
| Insolation (S⊕) | 1.00 | 318.00 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 4.280 M⊕ | Direct mass measurement (not derived). |
| Minimum mass (M sin i) | 3.410 M⊕ | Lower bound from radial-velocity fitting. |
| Computed mass | 3.419 M⊕ | Model-computed mass (e.g. from mass-radius relation). |
Star Catalogue Identifiers
HIP
HIP 115752
TIC
TIC 301289516
Gaia DR2
Gaia DR2 2643842302456085888
Gaia DR3
Gaia DR3 2643842302456085888
System
GJ 9827
Percentile among Super-Earth cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 1.21 Earth days (0.3% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0189 AU.
Transit Fingerprint
Depth
0.059 %
Duration
1.260 h
Impact parameter b
0.300
Rp / R★
0.024000
Transit midpoint (BJD)
2,457,738.8259
Photometric dip
Transit produces a flux drop of 586 ppm lasting ≈ 1.26 h.
Extended Orbital Architecture
Planet / star radius ratio
0.024000
Semi-major axis / stellar radius
6.719
Impact parameter (b)
0.300
RV semi-amplitude (K)
3.530 m/s
Transit mid-time (BJD)
2,457,738.8259
Angular separation (arcsec)
0.63700
Eq. Temperature
1,035K
(762 °C)
Insolation (S⊕)
318.00
Earth = 1.00
Earth Similarity (ESI)
0.274
0 = alien, 1 = Earth-identical
Inside the inner HZ boundary (too hot for liquid water) — the dayside is scorched. Close-orbiting tidally-locked around a cool host.
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
Niraula et al. 2017Instrument
Kepler CCD Array
Publication
2017-12
Observation locale
Space
Discovery cohort
Planets confirmed in 2017 at K2 (12 shown).
Host System: GJ 9827
Spectral Class
K-type orange
Effective Temperature
4,236 K — cooler than the Sun (5,778 K)
Estimated Age
5.46 Gyr — older than the Sun (4.6 Gyr)
Stellar Radius
0.580 R☉
Stellar Mass
0.620 M☉
Metallicity [Fe/H]
-0.29
Extended Stellar Properties
Surface gravity (log g)
4.719 dex
Stellar density
3.970 g/cm³
Systemic radial velocity
31.95 km/s
Rotational v·sin i
1.75 km/s
Rotation period
28.16 days
Activity index (log R'HK)
-5.280
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 18 bands
Astrometric Data
Parallax
33.686 mas
Total Proper Motion
433.678 mas/yr
PM Right Ascension
376.02 mas/yr
PM Declination
216.07 mas/yr
Galactic Cartesian (pc)
x = 0.989 · y = -0.143 · z = -0.022
Equatorial (J2000)
RA 351.77178° · Dec -1.28534°
Galactic ℓ, b
81.348° · -57.183°
Ecliptic λ, β
351.932° · 2.082°
HTM-20 index
-676985054
Similar Worlds
DMPP-3 A b
Super-Earth · K-type orange
Radius 1.44 R⊕ · 152.9 ly
K2-162 b
Super-Earth · K-type orange
Radius 1.44 R⊕ · 405.8 ly
Kepler-1007 b
Super-Earth · K-type orange
Radius 1.44 R⊕ · 1,190.5 ly
K2-36 b
Super-Earth · K-type orange
Radius 1.43 R⊕ · 358.0 ly
Kepler-1335 b
Super-Earth · K-type orange
Radius 1.45 R⊕ · 2,028.2 ly
Kepler-1259 b
Super-Earth · K-type orange
Radius 1.43 R⊕ · 2,627.4 ly