Key parameters at a glance
- A radius of 3.74 Earth radii
- A mass of 13.50 Earth masses
- Surface gravity around 0.97 g
- An orbital period of 284.000 days
- Semi-major axis 0.8120 AU
- Equilibrium temperature 278 K (5 °C)
- Distance from Earth 174.85 light-years
- Earth Similarity Index 0.637
- Travel time at Voyager 1 speed 3,083,456 years
5 siblings around HD 191939
HD 191939 g shares its host star with 5 other confirmed planets. Side-by-side measurements below.
| Planet | Type | Radius (R⊕) | Mass (M⊕) | Period (d) | Eq. T (K) | Year |
|---|---|---|---|---|---|---|
| HD 191939 b | Sub-Neptune | 3.41 | 10.00 | 8.880 | 880 | 2020 |
| HD 191939 c | Sub-Neptune | 3.20 | 8.00 | 28.580 | 600 | 2020 |
| HD 191939 d | Sub-Neptune | 3.00 | 2.80 | 38.353 | 540 | 2020 |
| HD 191939 e | Gas Giant | 13.00 | 112.20 | 101.120 | 390 | 2022 |
| HD 191939 g this | Sub-Neptune | 3.74 | 13.50 | 284.000 | 278 | 2022 |
| HD 191939 f | Gas Giant | 13.20 | 915.35 | 2,898.000 | 125 | 2022 |
HD 191939 g Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#75of 1978
top 3.7%
This planet
3.74R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | HD 191939 g | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 3.74 | 11.21 |
| Mass (M⊕) | 1.00 | 13.50 | 317.83 |
| Density (g/cm³) | 5.51 | 1.42 | 1.33 |
| Surface Gravity (g) | 1.00 | 0.97 | 2.53 |
| Insolation (S⊕) | 1.00 | 0.99 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Minimum mass (M sin i) | 13.500 M⊕ | Lower bound from radial-velocity fitting. |
Star Catalogue Identifiers
HD
HD 191939
HIP
HIP 99175
TIC
TIC 269701147
Gaia DR2
Gaia DR2 2248126315275354496
Gaia DR3
Gaia DR3 2248126315275354496
System
HD 191939
Percentile among Sub-Neptune cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 284.00 Earth days (77.8% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.8120 AU.
Extended Orbital Architecture
Semi-major axis / stellar radius
186.000
RV semi-amplitude (K)
1.530 m/s
Transit mid-time (BJD)
2,459,385.0000
Long. of periastron (ω)
18.00°
Angular separation (arcsec)
15.10000
Eq. Temperature
278K
(5 °C)
Insolation (S⊕)
0.99
Earth = 1.00
Earth Similarity (ESI)
0.637
0 = alien, 1 = Earth-identical
Within the conservative habitable zone — liquid water is physically possible with adequate atmospheric pressure.
Discovery Paper
Primary reference
Orell Miquel et al. 2022Instrument
Multiple Instruments
Publication
2022-11
Observation locale
Ground
Discovery cohort
Planets confirmed in 2022 at Multiple Observatories (12 shown).
Host System: HD 191939
Spectral Class
G-type yellow (Sun-like)
Effective Temperature
5,348 K — cooler than the Sun (5,778 K)
Estimated Age
8.70 Gyr — older than the Sun (4.6 Gyr)
Stellar Radius
0.940 R☉
Stellar Mass
0.810 M☉
Metallicity [Fe/H]
-0.15
Extended Stellar Properties
Surface gravity (log g)
4.300 dex
Stellar density
1.370 g/cm³
Systemic radial velocity
-9.50 km/s
Rotational v·sin i
2.00 km/s
Activity index (log R'HK)
-5.110
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 11 bands
Astrometric Data
Parallax
18.625 mas
Total Proper Motion
163.283 mas/yr
PM Right Ascension
150.26 mas/yr
PM Declination
-63.91 mas/yr
Galactic Cartesian (pc)
x = 0.208 · y = -0.333 · z = 0.919
Equatorial (J2000)
RA 302.02562° · Dec 66.85030°
Galactic ℓ, b
99.987° · 17.722°
Ecliptic λ, β
16.039° · 77.471°
HTM-20 index
-1738980752
Similar Worlds
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Sub-Neptune · G-type yellow (Sun-like)
Radius 3.74 R⊕ · 6,445.0 ly
TOI-1136 f
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Kepler-1065 b
Sub-Neptune · G-type yellow (Sun-like)
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K2-357 b
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pi Men d
Sub-Neptune · G-type yellow (Sun-like)
Radius 3.72 R⊕ · 59.6 ly