Key parameters at a glance
- A radius of 2.26 Earth radii
- A mass of 3.65 Earth masses
- Surface gravity around 0.71 g
- An orbital period of 4.696 days
- Semi-major axis 0.0437 AU
- Equilibrium temperature 553 K (280 °C)
- Distance from Earth 209.49 light-years
- Earth Similarity Index 0.442
- Travel time at Voyager 1 speed 3,694,402 years
- Almost certainly tidally locked to its host star given the close orbit
2 siblings around TOI-663
TOI-663 c shares its host star with 2 other confirmed planets. Side-by-side measurements below.
TOI-663 c Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#1572of 1978
top 79.4%
This planet
2.26R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | TOI-663 c | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 2.26 | 11.21 |
| Mass (M⊕) | 1.00 | 3.65 | 317.83 |
| Density (g/cm³) | 5.51 | 1.73 | 1.33 |
| Surface Gravity (g) | 1.00 | 0.71 | 2.53 |
| Insolation (S⊕) | 1.00 | 22.30 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 3.650 M⊕ | Direct mass measurement (not derived). |
Star Catalogue Identifiers
TIC
TIC 54962195
Gaia DR2
Gaia DR2 3762515188088861184
Gaia DR3
Gaia DR3 3762515188088861184
System
TOI-663
Percentile among Sub-Neptune cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 4.70 Earth days (1.3% of a terrestrial year) at a mean orbital distance of 0.0437 AU.
Transit Fingerprint
Depth
0.197 %
Duration
2.164 h
Impact parameter b
0.230
Rp / R★
0.040400
Transit midpoint (BJD)
2,458,543.4059
Photometric dip
Transit produces a flux drop of 1,969 ppm lasting ≈ 2.16 h.
Extended Orbital Architecture
Planet / star radius ratio
0.040400
Impact parameter (b)
0.230
RV semi-amplitude (K)
2.180 m/s
Transit mid-time (BJD)
2,458,543.4059
Angular separation (arcsec)
0.68000
Eq. Temperature
553K
(280 °C)
Insolation (S⊕)
22.30
Earth = 1.00
Earth Similarity (ESI)
0.442
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
Cointepas et al. 2024Instrument
TESS CCD Array
Publication
2024-05
Observation locale
Space
Discovery cohort
Planets confirmed in 2024 at Transiting Exoplanet Survey Satellite (TESS) (12 shown).
Host System: TOI-663
Spectral Class
M-type red dwarf
Effective Temperature
3,681 K — cooler than the Sun (5,778 K)
Estimated Age
—
Stellar Radius
0.512 R☉
Stellar Mass
0.514 M☉
Metallicity [Fe/H]
0.07
Extended Stellar Properties
Surface gravity (log g)
4.727 dex
Stellar density
5.347 g/cm³
Rotation period
30.00 days
Activity index (log R'HK)
-4.810
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 11 bands
Astrometric Data
Parallax
15.540 mas
Total Proper Motion
164.616 mas/yr
PM Right Ascension
-142.18 mas/yr
PM Declination
-82.96 mas/yr
Galactic Cartesian (pc)
x = -0.930 · y = 0.337 · z = -0.148
Equatorial (J2000)
RA 160.06585° · Dec -8.51108°
Galactic ℓ, b
256.572° · 42.254°
Ecliptic λ, β
164.917° · -15.659°
HTM-20 index
-595525992
Similar Worlds
GJ 3929 c
Sub-Neptune · M-type red dwarf
Radius 2.26 R⊕ · 51.6 ly
K2-9 b
Sub-Neptune · M-type red dwarf
Radius 2.25 R⊕ · 270.6 ly
Kepler-267 d
Sub-Neptune · M-type red dwarf
Radius 2.27 R⊕ · 864.3 ly
GJ 667 C b
Sub-Neptune · M-type red dwarf
Radius 2.25 R⊕ · 23.6 ly
TOI-663 b
Sub-Neptune · M-type red dwarf
Radius 2.27 R⊕ · 209.5 ly
Kepler-155 c
Sub-Neptune · M-type red dwarf
Radius 2.24 R⊕ · 957.3 ly