Key parameters at a glance
- A radius of 2.90 Earth radii
- A mass of 10.90 Earth masses
- Surface gravity around 1.30 g
- An orbital period of 6.527 days
- Semi-major axis 0.0730 AU
- Equilibrium temperature 1,129 K (856 °C)
- Distance from Earth 324.37 light-years
- Earth Similarity Index 0.213
- Travel time at Voyager 1 speed 5,720,184 years
HD 77946 b Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#637of 1978
top 32.2%
This planet
2.90R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | HD 77946 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 2.90 | 11.21 |
| Mass (M⊕) | 1.00 | 10.90 | 317.83 |
| Density (g/cm³) | 5.51 | 2.44 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.30 | 2.53 |
| Insolation (S⊕) | 1.00 | 413.10 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 10.900 M⊕ | Direct mass measurement (not derived). |
Star Catalogue Identifiers
HD
HD 77946
HIP
HIP 44746
TIC
TIC 39699648
Gaia DR2
Gaia DR2 1011435012611142784
Gaia DR3
Gaia DR3 1011435012611767552
System
HD 77946
Percentile among Sub-Neptune cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 6.53 Earth days (1.8% of a terrestrial year) on a mildly elliptical path at a mean orbital distance of 0.0730 AU.
Transit Fingerprint
Depth
0.042 %
Duration
2.976 h
Impact parameter b
0.593
Rp / R★
0.020157
Transit midpoint (BJD)
2,458,875.9989
Photometric dip
Transit produces a flux drop of 415 ppm lasting ≈ 2.98 h.
Extended Orbital Architecture
Planet / star radius ratio
0.020157
Semi-major axis / stellar radius
12.009
Impact parameter (b)
0.593
RV semi-amplitude (K)
3.400 m/s
Transit mid-time (BJD)
2,458,875.9989
Long. of periastron (ω)
9.20°
Angular separation (arcsec)
0.73400
Eq. Temperature
1,129K
(856 °C)
Insolation (S⊕)
413.10
Earth = 1.00
Earth Similarity (ESI)
0.213
0 = alien, 1 = Earth-identical
Inside the inner HZ boundary (too hot for liquid water) — the dayside is scorched.
Detection Signatures
Transit photometry
A transit dip has been observed from at least one telescope.
Radial velocity
Stellar wobble has been measured spectroscopically.
Discovery Paper
Primary reference
Palethorpe et al. 2024Instrument
TESS CCD Array
Publication
2024-03
Observation locale
Space
Discovery cohort
Planets confirmed in 2024 at Transiting Exoplanet Survey Satellite (TESS) (12 shown).
Host System: HD 77946
Spectral Class
F-type yellow-white
Effective Temperature
6,007 K — hotter than the Sun (5,778 K)
Estimated Age
3.10 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
1.317 R☉
Stellar Mass
1.197 M☉
Metallicity [Fe/H]
0.22
Extended Stellar Properties
Surface gravity (log g)
4.276 dex
Stellar density
0.734 g/cm³
Rotation period
13.56 days
Activity index (log R'HK)
-5.010
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 11 bands
Astrometric Data
Parallax
10.026 mas
Total Proper Motion
79.786 mas/yr
PM Right Ascension
-68.54 mas/yr
PM Declination
-40.84 mas/yr
Galactic Cartesian (pc)
x = -0.500 · y = 0.470 · z = 0.727
Equatorial (J2000)
RA 136.77764° · Dec 46.67243°
Galactic ℓ, b
173.226° · 42.258°
Ecliptic λ, β
124.756° · 28.718°
HTM-20 index
1555597987
Similar Worlds
Kepler-1921 b
Sub-Neptune · F-type yellow-white
Radius 2.89 R⊕ · 3,030.0 ly
Kepler-631 b
Sub-Neptune · F-type yellow-white
Radius 2.90 R⊕ · 2,485.2 ly
Kepler-1239 b
Sub-Neptune · F-type yellow-white
Radius 2.90 R⊕ · 6,981.7 ly
Kepler-642 b
Sub-Neptune · F-type yellow-white
Radius 2.90 R⊕ · 2,549.2 ly
Kepler-1518 c
Sub-Neptune · F-type yellow-white
Radius 2.90 R⊕ · 2,946.9 ly
Kepler-1700 b
Sub-Neptune · F-type yellow-white
Radius 2.90 R⊕ · 2,340.5 ly