Key parameters at a glance
- A radius of 2.73 Earth radii
- A mass of 8.41 Earth masses
- Surface gravity around 1.13 g
- An orbital period of 1.580 days
- Semi-major axis 0.0151 AU
- Equilibrium temperature 567 K (294 °C)
- Distance from Earth 47.76 light-years
- Earth Similarity Index 0.431
- Travel time at Voyager 1 speed 842,213 years
- Almost certainly tidally locked to its host star given the close orbit
Context from the literature
GJ 1214 b is an exoplanet that orbits the star GJ 1214, discovered in December 2009. Its parent star is 48 light-years (15 pc) from the Sun, in the constellation Ophiuchus. At the time of its discovery, GJ 1214 b was the most likely known candidate for being an ocean planet. For that reason, scientists at that time often called the planet a "waterworld". However, a recent study of the planet's internal structure informed by observations taken with the James Webb Space Telescope suggests that a "waterworld" composition is implausible and the planet is more likely to host a thick gaseous envelope consisting of hydrogen, helium, water and other volatile chemicals such as methane or carbon dioxide.
Excerpted from Wikipedia · full article
GJ 1214 b Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#822of 1978
top 41.5%
This planet
2.73R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | GJ 1214 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 2.73 | 11.21 |
| Mass (M⊕) | 1.00 | 8.41 | 317.83 |
| Density (g/cm³) | 5.51 | 2.26 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.13 | 2.53 |
| Insolation (S⊕) | 1.00 | 17.20 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 8.410 M⊕ | Direct mass measurement (not derived). |
| Minimum mass (M sin i) | 8.410 M⊕ | Lower bound from radial-velocity fitting. |
Star Catalogue Identifiers
TIC
TIC 467929202
Gaia DR2
Gaia DR2 4393265392167891712
Gaia DR3
Gaia DR3 4393265392168829056
System
GJ 1214
Percentile among Sub-Neptune cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 1.58 Earth days (0.4% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0150 AU.
Transit Fingerprint
Depth
1.343 %
Duration
0.870 h
Impact parameter b
0.264
Rp / R★
0.115890
Transit midpoint (BJD)
2,459,639.7813
Photometric dip
Transit produces a flux drop of 13,430 ppm lasting ≈ 0.87 h.
Extended Orbital Architecture
Planet / star radius ratio
0.115890
Semi-major axis / stellar radius
14.970
Impact parameter (b)
0.264
RV semi-amplitude (K)
14.380 m/s
Transit mid-time (BJD)
2,459,639.7813
Long. of periastron (ω)
77.00°
Angular separation (arcsec)
1.03000
Eq. Temperature
567K
(294 °C)
Insolation (S⊕)
17.20
Earth = 1.00
Earth Similarity (ESI)
0.431
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.
Detection Signatures
Transit photometry
A transit dip has been observed from at least one telescope.
Radial velocity
Stellar wobble has been measured spectroscopically.
Orbital-brightness modulation
Host star brightness varies with the planet's orbit.
Discovery Paper
Primary reference
Charbonneau et al. 2009Instrument
Apogee CCD Sensor
Publication
2009-12
Observation locale
Ground
Host System: GJ 1214
Spectral Class
M-type red dwarf
Effective Temperature
3,101 K — cooler than the Sun (5,778 K)
Estimated Age
3.00 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
0.216 R☉
Stellar Mass
0.182 M☉
Metallicity [Fe/H]
0.24
Extended Stellar Properties
Surface gravity (log g)
5.029 dex
Stellar density
25.410 g/cm³
Systemic radial velocity
20.91 km/s
Rotational v·sin i
2.00 km/s
Rotation period
124.70 days
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 11 bands
Astrometric Data
Parallax
68.265 mas
Total Proper Motion
948.051 mas/yr
PM Right Ascension
580.45 mas/yr
PM Declination
-749.59 mas/yr
Galactic Cartesian (pc)
x = -0.193 · y = -0.977 · z = 0.086
Equatorial (J2000)
RA 258.83140° · Dec 4.96068°
Galactic ℓ, b
26.162° · 23.607°
Ecliptic λ, β
257.382° · 27.912°
HTM-20 index
-2037770512
Observation Record
RV measurements
1
Stellar spectra
2
Transmission spectra
26
Emission spectra
1
Archive notes
3
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