Key parameters at a glance
- A radius of 11.59 Earth radii
- A mass of 2,493.00 Earth masses
- Surface gravity around 18.56 g
- An orbital period of 9.485 days
- Semi-major axis 0.0761 AU
- Equilibrium temperature 541 K (268 °C)
- Distance from Earth 496.47 light-years
- Earth Similarity Index 0.301
- Travel time at Voyager 1 speed 8,755,273 years
- Almost certainly tidally locked to its host star given the close orbit
TOI-6303 b Planet Profile
Physical Specs
Classification
Planet Type
Gas Giant
Discovery
Size rank in cohort
Rank by radius
#1580of 1771
top 89.2%
This planet
11.59R⊕
Gas Giant median
13.52R⊕
Nearest-size peers
| Metric | Earth | TOI-6303 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 11.59 | 11.21 |
| Mass (M⊕) | 1.00 | 2,493.00 | 317.83 |
| Density (g/cm³) | 5.51 | 8.82 | 1.33 |
| Surface Gravity (g) | 1.00 | 18.56 | 2.53 |
| Insolation (S⊕) | 1.00 | 14.28 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 2,493.000 M⊕ | Direct mass measurement (not derived). |
Star Catalogue Identifiers
TIC
TIC 186810676
Gaia DR2
Gaia DR2 239050153051494272
Gaia DR3
Gaia DR3 239050153051494272
System
TOI-6303
Percentile among Gas Giant cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 9.49 Earth days (2.6% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0761 AU.
Transit Fingerprint
Depth
3.242 %
Duration
2.918 h
Impact parameter b
0.450
Rp / R★
0.175000
Transit midpoint (BJD)
2,459,901.0144
Photometric dip
Transit produces a flux drop of 32,417 ppm lasting ≈ 2.92 h.
Extended Orbital Architecture
Planet / star radius ratio
0.175000
Semi-major axis / stellar radius
26.950
Impact parameter (b)
0.450
RV semi-amplitude (K)
1,000.000 m/s
Transit mid-time (BJD)
2,459,901.0144
Long. of periastron (ω)
117.00°
Angular separation (arcsec)
0.50000
Eq. Temperature
541K
(268 °C)
Insolation (S⊕)
14.28
Earth = 1.00
Earth Similarity (ESI)
0.301
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.
Discovery Paper
Primary reference
Hotnisky et al. 2025Instrument
TESS CCD Array
Publication
2025-07
Observation locale
Space
Discovery cohort
Planets confirmed in 2025 at Transiting Exoplanet Survey Satellite (TESS) (12 shown).
Host System: TOI-6303
Spectral Class
K-type orange
Effective Temperature
3,977 K — cooler than the Sun (5,778 K)
Estimated Age
6.40 Gyr — older than the Sun (4.6 Gyr)
Stellar Radius
0.609 R☉
Stellar Mass
0.644 M☉
Metallicity [Fe/H]
0.44
Extended Stellar Properties
Surface gravity (log g)
4.670 dex
Stellar density
4.010 g/cm³
Rotational v·sin i
2.00 km/s
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 16 bands
Astrometric Data
Parallax
6.541 mas
Total Proper Motion
48.338 mas/yr
PM Right Ascension
32.94 mas/yr
PM Declination
-35.38 mas/yr
Galactic Cartesian (pc)
x = 0.523 · y = 0.557 · z = 0.645
Equatorial (J2000)
RA 46.78065° · Dec 40.14717°
Galactic ℓ, b
149.233° · -15.695°
Ecliptic λ, β
55.703° · 21.714°
HTM-20 index
1241493747
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