Key parameters at a glance
- A radius of 2.83 Earth radii
- A mass of 8.40 Earth masses
- Surface gravity around 1.05 g
- An orbital period of 8.784 days
- Semi-major axis 0.0660 AU
- Equilibrium temperature 450 K (177 °C)
- Distance from Earth 30.89 light-years
- Earth Similarity Index 0.518
- Travel time at Voyager 1 speed 544,718 years
- Almost certainly tidally locked to its host star given the close orbit
Context from the literature
Gliese 176 b is a super-Earth exoplanet approximately 31 light years away in the constellation of Taurus. This planet orbits very close to its parent red dwarf star Gliese 176.
Excerpted from Wikipedia · full article
HD 285968 b Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#703of 1978
top 35.5%
This planet
2.83R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | HD 285968 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 2.83 | 11.21 |
| Mass (M⊕) | 1.00 | 8.40 | 317.83 |
| Density (g/cm³) | 5.51 | 2.04 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.05 | 2.53 |
| Insolation (S⊕) | 1.00 | — | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Minimum mass (M sin i) | 8.400 M⊕ | Lower bound from radial-velocity fitting. |
Star Catalogue Identifiers
HD
HD 285968
HIP
HIP 21932
TIC
TIC 397354290
Gaia DR2
Gaia DR2 3409711211681795584
Gaia DR3
Gaia DR3 3409711211681795584
System
HD 285968
Percentile among Sub-Neptune cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 8.78 Earth days (2.4% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0660 AU.
Extended Orbital Architecture
RV semi-amplitude (K)
4.120 m/s
Transit mid-time (BJD)
2,455,191.0000
Long. of periastron (ω)
0.00°
Angular separation (arcsec)
6.97000
Eq. Temperature
450K
(177 °C)
Insolation (S⊕)
—
Earth = 1.00
Earth Similarity (ESI)
0.518
0 = alien, 1 = Earth-identical
Insufficient insolation data — the surface is too hot to retain surface water. Close-orbiting tidally-locked around a cool host.
Discovery Paper
Primary reference
Forveille et al. 2009Instrument
HARPS Spectrograph
Publication
2009-01
Observation locale
Ground
Discovery cohort
Planets confirmed in 2008 at La Silla Observatory (12 shown).
Host System: HD 285968
Spectral Class
M-type red dwarf
Effective Temperature
3,703 K — cooler than the Sun (5,778 K)
Estimated Age
3.62 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
0.478 R☉
Stellar Mass
0.500 M☉
Metallicity [Fe/H]
-0.10
Extended Stellar Properties
Surface gravity (log g)
4.749 dex
Stellar density
5.923 g/cm³
Systemic radial velocity
26.41 km/s
Rotational v·sin i
0.80 km/s
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 13 bands
Astrometric Data
Parallax
105.563 mas
Total Proper Motion
1,295.146 mas/yr
PM Right Ascension
656.38 mas/yr
PM Declination
-1,116.50 mas/yr
Galactic Cartesian (pc)
x = 0.312 · y = 0.893 · z = 0.325
Equatorial (J2000)
RA 70.73539° · Dec 18.95336°
Galactic ℓ, b
180.021° · -17.427°
Ecliptic λ, β
71.783° · -3.276°
HTM-20 index
116750830
Observation Record
Photometric series
1
RV measurements
5
Stellar spectra
2
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