Key parameters at a glance
- A radius of 4.29 Earth radii
- A mass of 8.00 Earth masses
- Surface gravity around 0.43 g
- An orbital period of 12.886 days
- Semi-major axis 0.0970 AU
- Equilibrium temperature 588 K (315 °C)
- Distance from Earth 388.91 light-years
- Earth Similarity Index 0.279
- Travel time at Voyager 1 speed 6,858,400 years
- Almost certainly tidally locked to its host star given the close orbit
1 sibling around TOI-1803
TOI-1803 c shares its host star with 1 other confirmed planet. Side-by-side measurements below.
| Planet | Type | Radius (R⊕) | Mass (M⊕) | Period (d) | Eq. T (K) | Year |
|---|---|---|---|---|---|---|
| TOI-1803 b | Sub-Neptune | 2.99 | 10.32 | 6.293 | 747 | 2025 |
| TOI-1803 c this | Neptune-like | 4.29 | 8.00 | 12.886 | 588 | 2025 |
TOI-1803 c Planet Profile
Physical Specs
Classification
Planet Type
Neptune-like
Discovery
Size rank in cohort
Rank by radius
#499of 574
top 86.8%
This planet
4.29R⊕
Neptune-like median
6.39R⊕
Nearest-size peers
| Metric | Earth | TOI-1803 c | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 4.29 | 11.21 |
| Mass (M⊕) | 1.00 | 8.00 | 317.83 |
| Density (g/cm³) | 5.51 | 0.42 | 1.33 |
| Surface Gravity (g) | 1.00 | 0.43 | 2.53 |
| Insolation (S⊕) | 1.00 | 22.00 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 8.000 M⊕ | Direct mass measurement (not derived). |
Star Catalogue Identifiers
TIC
TIC 144401492
Gaia DR2
Gaia DR2 4031575166693272832
Gaia DR3
Gaia DR3 4031575166693272832
System
TOI-1803
Percentile among Neptune-like cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 12.89 Earth days (3.5% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0970 AU.
Transit Fingerprint
Depth
0.317 %
Duration
2.400 h
Impact parameter b
0.779
Rp / R★
0.055000
Transit midpoint (BJD)
2,458,911.6747
Photometric dip
Transit produces a flux drop of 3,170 ppm lasting ≈ 2.40 h.
Extended Orbital Architecture
Planet / star radius ratio
0.055000
Semi-major axis / stellar radius
29.300
Impact parameter (b)
0.779
RV semi-amplitude (K)
2.100 m/s
Transit mid-time (BJD)
2,458,911.6747
Angular separation (arcsec)
0.81300
Eq. Temperature
588K
(315 °C)
Insolation (S⊕)
22.00
Earth = 1.00
Earth Similarity (ESI)
0.279
0 = alien, 1 = Earth-identical
Inside the inner HZ boundary (too hot for liquid water) — the surface is too hot to retain surface water. Close-orbiting tidally-locked around a cool host.
Detection Signatures
Transit photometry
A transit dip has been observed from at least one telescope.
Radial velocity
Stellar wobble has been measured spectroscopically.
Transit timing variations
Gravitational interactions from neighbours have been detected.
Discovery Paper
Primary reference
Zingales et al. 2025Instrument
TESS CCD Array
Publication
2025-03
Observation locale
Space
Discovery cohort
Planets confirmed in 2025 at Transiting Exoplanet Survey Satellite (TESS) (12 shown).
Host System: TOI-1803
Spectral Class
K-type orange
Effective Temperature
4,687 K — cooler than the Sun (5,778 K)
Estimated Age
1.40 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
0.715 R☉
Stellar Mass
0.756 M☉
Metallicity [Fe/H]
0.01
Extended Stellar Properties
Surface gravity (log g)
4.620 dex
Stellar density
2.862 g/cm³
Systemic radial velocity
2.10 km/s
Rotational v·sin i
1.00 km/s
Rotation period
13.66 days
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 16 bands
Astrometric Data
Parallax
8.358 mas
Total Proper Motion
86.500 mas/yr
PM Right Ascension
-86.45 mas/yr
PM Declination
3.09 mas/yr
Galactic Cartesian (pc)
x = -0.817 · y = 0.028 · z = 0.576
Equatorial (J2000)
RA 178.04611° · Dec 35.17180°
Galactic ℓ, b
176.847° · 75.013°
Ecliptic λ, β
162.680° · 31.159°
HTM-20 index
683606242
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