Key parameters at a glance
- A radius of 6.17 Earth radii
- A mass of 31.50 Earth masses
- Surface gravity around 0.83 g
- An orbital period of 811.300 days
- Semi-major axis 1.5700 AU
- Distance from Earth 79.36 light-years
- Earth Similarity Index 0.418
- Travel time at Voyager 1 speed 1,399,536 years
1 sibling around HD 156668
HD 156668 c 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 |
|---|---|---|---|---|---|---|
| HD 156668 b | Super-Earth | 1.87 | 4.15 | 4.646 | — | 2010 |
| HD 156668 c this | Neptune-like | 6.17 | 31.50 | 811.300 | — | 2021 |
HD 156668 c Planet Profile
Physical Specs
Classification
Planet Type
Neptune-like
Discovery
Size rank in cohort
Rank by radius
#268of 574
top 46.5%
This planet
6.17R⊕
Neptune-like median
6.39R⊕
Nearest-size peers
| Metric | Earth | HD 156668 c | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 6.17 | 11.21 |
| Mass (M⊕) | 1.00 | 31.50 | 317.83 |
| Density (g/cm³) | 5.51 | 0.74 | 1.33 |
| Surface Gravity (g) | 1.00 | 0.83 | 2.53 |
| Insolation (S⊕) | 1.00 | — | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Minimum mass (M sin i) | 31.497 M⊕ | Lower bound from radial-velocity fitting. |
Star Catalogue Identifiers
HD
HD 156668
HIP
HIP 84607
TIC
TIC 257715493
Gaia DR2
Gaia DR2 4575374857376398976
Gaia DR3
Gaia DR3 4575374857376398976
System
HD 156668
Percentile among Neptune-like cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts about 2.22 Earth years on a nearly circular orbit at a mean orbital distance of 1.5700 AU.
Extended Orbital Architecture
RV semi-amplitude (K)
2.560 m/s
Transit mid-time (BJD)
2,455,890.0000
Long. of periastron (ω)
-10.89°
Angular separation (arcsec)
64.50000
Eq. Temperature
—
Insolation (S⊕)
—
Earth = 1.00
Earth Similarity (ESI)
0.418
0 = alien, 1 = Earth-identical
Discovery Paper
Primary reference
Rosenthal et al. 2021Instrument
Multiple Instruments
Publication
2021-07
Observation locale
Ground
Discovery cohort
Planets confirmed in 2021 at Multiple Observatories (12 shown).
Host System: HD 156668
Spectral Class
K-type orange
Effective Temperature
4,904 K — cooler than the Sun (5,778 K)
Estimated Age
8.60 Gyr — older than the Sun (4.6 Gyr)
Stellar Radius
0.775 R☉
Stellar Mass
0.785 M☉
Metallicity [Fe/H]
0.05
Extended Stellar Properties
Surface gravity (log g)
4.551 dex
Stellar density
2.533 g/cm³
Systemic radial velocity
-44.57 km/s
Rotational v·sin i
0.50 km/s
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 11 bands
Astrometric Data
Parallax
41.069 mas
Total Proper Motion
228.612 mas/yr
PM Right Ascension
-72.63 mas/yr
PM Declination
216.77 mas/yr
Galactic Cartesian (pc)
x = -0.160 · y = -0.858 · z = 0.488
Equatorial (J2000)
RA 259.41835° · Dec 29.22816°
Galactic ℓ, b
51.969° · 32.115°
Ecliptic λ, β
254.869° · 52.113°
HTM-20 index
-1072161331
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