Key parameters at a glance
- A radius of 4.72 Earth radii
- A mass of 29.32 Earth masses
- Surface gravity around 1.32 g
- An orbital period of 0.792 days
- Semi-major axis 0.0168 AU
- Equilibrium temperature 1,978 K (1705 °C)
- Distance from Earth 262.35 light-years
- Earth Similarity Index 0.093
- Travel time at Voyager 1 speed 4,626,561 years
LTT 9779 b Planet Profile
Physical Specs
Classification
Planet Type
Neptune-like
Discovery
Size rank in cohort
Rank by radius
#426of 574
top 74.0%
This planet
4.72R⊕
Neptune-like median
6.39R⊕
Nearest-size peers
| Metric | Earth | LTT 9779 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 4.72 | 11.21 |
| Mass (M⊕) | 1.00 | 29.32 | 317.83 |
| Density (g/cm³) | 5.51 | 1.54 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.32 | 2.53 |
| Insolation (S⊕) | 1.00 | 1,781.16 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 29.320 M⊕ | Direct mass measurement (not derived). |
Star Catalogue Identifiers
HIP
HIP 117883
TIC
TIC 183985250
Gaia DR2
Gaia DR2 2307504062045842688
Gaia DR3
Gaia DR3 2307504062045842688
System
LTT 9779
Percentile among Neptune-like cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts roughly 19 hours long on a nearly circular orbit at a mean orbital distance of 0.0168 AU.
Transit Fingerprint
Depth
0.156 %
Duration
0.366 h
Rp / R★
0.045500
Transit midpoint (BJD)
2,458,354.2143
Photometric dip
Transit produces a flux drop of 1,562 ppm lasting ≈ 0.37 h.
Extended Orbital Architecture
Planet / star radius ratio
0.045500
Semi-major axis / stellar radius
3.877
RV semi-amplitude (K)
19.650 m/s
Transit mid-time (BJD)
2,458,354.2143
Long. of periastron (ω)
90.00°
Angular separation (arcsec)
0.20900
Eq. Temperature
1,978K
(1705 °C)
Insolation (S⊕)
1,781.16
Earth = 1.00
Earth Similarity (ESI)
0.093
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.
Orbital-brightness modulation
Host star brightness varies with the planet's orbit.
Discovery Paper
Primary reference
Jenkins et al. 2020Instrument
TESS CCD Array
Publication
2020-09
Observation locale
Space
Discovery cohort
Planets confirmed in 2020 at Transiting Exoplanet Survey Satellite (TESS) (12 shown).
Host System: LTT 9779
Spectral Class
G-type yellow (Sun-like)
Effective Temperature
5,443 K — cooler than the Sun (5,778 K)
Estimated Age
2.00 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
0.949 R☉
Stellar Mass
1.020 M☉
Metallicity [Fe/H]
0.27
Extended Stellar Properties
Surface gravity (log g)
4.350 dex
Stellar density
1.810 g/cm³
Systemic radial velocity
-10.63 km/s
Rotational v·sin i
1.06 km/s
Rotation period
45.00 days
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 11 bands
Astrometric Data
Parallax
12.403 mas
Total Proper Motion
257.265 mas/yr
PM Right Ascension
247.62 mas/yr
PM Declination
-69.80 mas/yr
Galactic Cartesian (pc)
x = 0.792 · y = -0.018 · z = -0.611
Equatorial (J2000)
RA 358.66888° · Dec -37.62822°
Galactic ℓ, b
348.065° · -74.101°
Ecliptic λ, β
341.834° · -33.562°
HTM-20 index
-1087343862
Observation Record
Photometric series
1
Transmission spectra
2
Emission spectra
1
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