Key parameters at a glance
- A radius of 3.89 Earth radii
- A mass of 14.40 Earth masses
- Surface gravity around 0.95 g
- An orbital period of 149.610 days
- Semi-major axis 0.5540 AU
- Equilibrium temperature 337 K (64 °C)
- Distance from Earth 79.37 light-years
- Earth Similarity Index 0.572
- Travel time at Voyager 1 speed 1,399,737 years
Context from the literature
HD 42618 is a well-studied star with an exoplanetary companion in the equatorial constellation of Orion. With an apparent visual magnitude of 6.85 it is too faint to be readily visible to the naked eye. This system is located at a distance of 79.6 light years from the Sun based on parallax measurements. It has a relatively high proper motion, traversing the celestial sphere at an angular rate of 0.321″ per year. HD 42618 is drifting closer with a radial velocity of −53.5 km/s and is predicted to come as near as 42.6 light-years in around 297,000 years.
Excerpted from Wikipedia · full article
HD 42618 b Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#28of 1978
top 1.4%
This planet
3.89R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | HD 42618 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 3.89 | 11.21 |
| Mass (M⊕) | 1.00 | 14.40 | 317.83 |
| Density (g/cm³) | 5.51 | 1.34 | 1.33 |
| Surface Gravity (g) | 1.00 | 0.95 | 2.53 |
| Insolation (S⊕) | 1.00 | 3.16 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Minimum mass (M sin i) | 14.400 M⊕ | Lower bound from radial-velocity fitting. |
Star Catalogue Identifiers
HD
HD 42618
HIP
HIP 29432
TIC
TIC 153289168
Gaia DR2
Gaia DR2 3319126988068404096
Gaia DR3
Gaia DR3 3319126988068404096
System
HD 42618
Percentile among Sub-Neptune cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 149.61 Earth days (41.0% of a terrestrial year) on a mildly elliptical path at a mean orbital distance of 0.5540 AU.
Extended Orbital Architecture
Semi-major axis / stellar radius
119.100
RV semi-amplitude (K)
1.890 m/s
Transit mid-time (BJD)
2,455,170.6000
Long. of periastron (ω)
101.00°
Angular separation (arcsec)
22.80000
Eq. Temperature
337K
(64 °C)
Insolation (S⊕)
3.16
Earth = 1.00
Earth Similarity (ESI)
0.572
0 = alien, 1 = Earth-identical
Inside the inner HZ boundary (too hot for liquid water) — liquid water is physically possible with adequate atmospheric pressure.
Discovery Paper
Primary reference
Fulton et al. 2016Instrument
Multiple Instruments
Publication
2016-10
Observation locale
Ground
Discovery cohort
Planets confirmed in 2016 at Multiple Observatories (12 shown).
Host System: HD 42618
Spectral Class
G-type yellow (Sun-like)
Effective Temperature
5,727 K — cooler than the Sun (5,778 K)
Estimated Age
3.72 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
0.999 R☉
Stellar Mass
1.015 M☉
Metallicity [Fe/H]
-0.09
Extended Stellar Properties
Surface gravity (log g)
4.440 dex
Stellar density
1.573 g/cm³
Systemic radial velocity
-53.70 km/s
Rotational v·sin i
2.00 km/s
Activity index (log R'HK)
-4.940
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 7 bands
Astrometric Data
Parallax
41.063 mas
Total Proper Motion
322.299 mas/yr
PM Right Ascension
197.31 mas/yr
PM Declination
-254.85 mas/yr
Galactic Cartesian (pc)
x = -0.052 · y = 0.992 · z = 0.118
Equatorial (J2000)
RA 93.00322° · Dec 6.78197°
Galactic ℓ, b
202.359° · -5.591°
Ecliptic λ, β
93.109° · -16.625°
HTM-20 index
-1463439828
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