Key parameters at a glance
- A radius of 2.43 Earth radii
- A mass of 6.50 Earth masses
- Surface gravity around 1.10 g
- An orbital period of 21.784 days
- Semi-major axis 0.1210 AU
- Equilibrium temperature 320 K (47 °C)
- Distance from Earth 10.72 light-years
- Earth Similarity Index 0.721
- Travel time at Voyager 1 speed 189,048 years
- Almost certainly tidally locked to its host star given the close orbit
Context from the literature
Gliese 887 c or Lacaille 9352 c is an exoplanet announced in 2020 and located 10.74 light years away, in the constellation of Piscis Austrinus.
Excerpted from Wikipedia · full article
3 siblings around GJ 887
GJ 887 c shares its host star with 3 other confirmed planets. Side-by-side measurements below.
GJ 887 c Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#1281of 1978
top 64.7%
This planet
2.43R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | GJ 887 c | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 2.43 | 11.21 |
| Mass (M⊕) | 1.00 | 6.50 | 317.83 |
| Density (g/cm³) | 5.51 | 2.49 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.10 | 2.53 |
| Insolation (S⊕) | 1.00 | 2.50 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Minimum mass (M sin i) | 6.500 M⊕ | Lower bound from radial-velocity fitting. |
Star Catalogue Identifiers
HD
HD 217987
HIP
HIP 114046
TIC
TIC 155315739
Gaia DR2
Gaia DR2 6553614253923452800
Gaia DR3
Gaia DR3 6553614253923452800
System
GJ 887
Percentile among Sub-Neptune cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 21.78 Earth days (6.0% of a terrestrial year) on a mildly elliptical path at a mean orbital distance of 0.1210 AU.
Extended Orbital Architecture
RV semi-amplitude (K)
2.540 m/s
Transit mid-time (BJD)
2,453,498.2000
Long. of periastron (ω)
200.00°
Angular separation (arcsec)
36.80000
Eq. Temperature
320K
(47 °C)
Insolation (S⊕)
2.50
Earth = 1.00
Earth Similarity (ESI)
0.721
0 = alien, 1 = Earth-identical
Inside the inner HZ boundary (too hot for liquid water) — liquid water is physically possible with adequate atmospheric pressure. Close-orbiting tidally-locked around a cool host.
Discovery Paper
Primary reference
Jeffers et al. 2020Instrument
HARPS Spectrograph
Publication
2020-06
Observation locale
Ground
Discovery cohort
Planets confirmed in 2020 at La Silla Observatory (4 shown).
Host System: GJ 887
Spectral Class
M-type red dwarf
Effective Temperature
3,688 K — cooler than the Sun (5,778 K)
Estimated Age
2.90 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
0.468 R☉
Stellar Mass
0.495 M☉
Metallicity [Fe/H]
-0.06
Extended Stellar Properties
Surface gravity (log g)
4.156 dex
Stellar density
6.056 g/cm³
Systemic radial velocity
8.17 km/s
Rotational v·sin i
2.50 km/s
Rotation period
38.70 days
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 8 bands
Astrometric Data
Parallax
304.219 mas
Total Proper Motion
6,895.546 mas/yr
PM Right Ascension
6,765.99 mas/yr
PM Declination
1,330.39 mas/yr
Galactic Cartesian (pc)
x = 0.788 · y = -0.189 · z = -0.586
Equatorial (J2000)
RA 346.50276° · Dec -35.84735°
Galactic ℓ, b
5.097° · -65.987°
Ecliptic λ, β
332.713° · -27.519°
HTM-20 index
215838338
Observation Record
Photometric series
1
Stellar spectra
2
Archive notes
1
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