Key parameters at a glance
- A radius of 1.03 Earth radii
- A mass of 1.09 Earth masses
- Surface gravity around 1.03 g
- An orbital period of 4.656 days
- Semi-major axis 0.0285 AU
- Equilibrium temperature 357 K (84 °C)
- Distance from Earth 12.11 light-years
- Earth Similarity Index 0.850
- Travel time at Voyager 1 speed 213,509 years
- Almost certainly tidally locked to its host star given the close orbit
2 siblings around YZ Cet
YZ Cet d shares its host star with 2 other confirmed planets. Side-by-side measurements below.
YZ Cet d Planet Profile
Physical Specs
Classification
Planet Type
Rocky Terrestrial
Discovery
Size rank in cohort
Rank by radius
#297of 570
top 51.9%
This planet
1.03R⊕
Rocky Terrestrial median
1.01R⊕
Nearest-size peers
| Metric | Earth | YZ Cet d | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 1.03 | 11.21 |
| Mass (M⊕) | 1.00 | 1.09 | 317.83 |
| Density (g/cm³) | 5.51 | 5.48 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.03 | 2.53 |
| Insolation (S⊕) | 1.00 | 2.70 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Minimum mass (M sin i) | 1.090 M⊕ | Lower bound from radial-velocity fitting. |
Star Catalogue Identifiers
HIP
HIP 5643
TIC
TIC 439403362
Gaia DR2
Gaia DR2 2358524597030794112
Gaia DR3
Gaia DR3 2358524597030794112
System
YZ Cet
Percentile among Rocky Terrestrial cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 4.66 Earth days (1.3% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0285 AU.
Eq. Temperature
357K
(84 °C)
Insolation (S⊕)
2.70
Earth = 1.00
Earth Similarity (ESI)
0.850
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
Astudillo Defru et al. 2017Instrument
HARPS Spectrograph
Publication
2017-09
Observation locale
Ground
Discovery cohort
Planets confirmed in 2017 at La Silla Observatory (12 shown).
Host System: YZ Cet
Spectral Class
M-type red dwarf
Effective Temperature
3,151 K — cooler than the Sun (5,778 K)
Estimated Age
3.80 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
0.157 R☉
Stellar Mass
0.142 M☉
Metallicity [Fe/H]
-0.18
Extended Stellar Properties
Surface gravity (log g)
5.170 dex
Systemic radial velocity
28.30 km/s
Rotational v·sin i
2.00 km/s
Rotation period
68.28 days
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 6 bands
Astrometric Data
Parallax
269.363 mas
Total Proper Motion
1,363.523 mas/yr
PM Right Ascension
1,205.18 mas/yr
PM Declination
637.76 mas/yr
Galactic Cartesian (pc)
x = 0.909 · y = 0.298 · z = -0.292
Equatorial (J2000)
RA 18.13308° · Dec -16.99624°
Galactic ℓ, b
149.724° · -78.755°
Ecliptic λ, β
9.785° · -22.742°
HTM-20 index
987040254
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