Key parameters at a glance
- A radius of 2.52 Earth radii
- A mass of 5.40 Earth masses
- Surface gravity around 0.85 g
- An orbital period of 7.446 days
- Semi-major axis 0.0534 AU
- Equilibrium temperature 435 K (162 °C)
- Distance from Earth 97.96 light-years
- Earth Similarity Index 0.539
- Travel time at Voyager 1 speed 1,727,518 years
- Almost certainly tidally locked to its host star given the close orbit
TOI-4438 b Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#1147of 1978
top 57.9%
This planet
2.52R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | TOI-4438 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 2.52 | 11.21 |
| Mass (M⊕) | 1.00 | 5.40 | 317.83 |
| Density (g/cm³) | 5.51 | 1.85 | 1.33 |
| Surface Gravity (g) | 1.00 | 0.85 | 2.53 |
| Insolation (S⊕) | 1.00 | 6.00 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 5.400 M⊕ | Direct mass measurement (not derived). |
Star Catalogue Identifiers
TIC
TIC 22233480
Gaia DR2
Gaia DR2 4606416269652179328
Gaia DR3
Gaia DR3 4606416269652179328
System
TOI-4438
Percentile among Sub-Neptune cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 7.45 Earth days (2.0% of a terrestrial year) on a mildly elliptical path at a mean orbital distance of 0.0534 AU.
Transit Fingerprint
Depth
0.405 %
Duration
2.021 h
Impact parameter b
0.390
Rp / R★
0.062000
Transit midpoint (BJD)
2,459,396.4117
Photometric dip
Transit produces a flux drop of 4,046 ppm lasting ≈ 2.02 h.
Extended Orbital Architecture
Planet / star radius ratio
0.062000
Semi-major axis / stellar radius
29.220
Impact parameter (b)
0.390
RV semi-amplitude (K)
3.500 m/s
Transit mid-time (BJD)
2,459,396.4117
Long. of periastron (ω)
-70.00°
Angular separation (arcsec)
1.78000
Eq. Temperature
435K
(162 °C)
Insolation (S⊕)
6.00
Earth = 1.00
Earth Similarity (ESI)
0.539
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
Goffo 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: TOI-4438
Spectral Class
M-type red dwarf
Effective Temperature
3,422 K — cooler than the Sun (5,778 K)
Estimated Age
5.10 Gyr — older than the Sun (4.6 Gyr)
Stellar Radius
0.372 R☉
Stellar Mass
0.368 M☉
Metallicity [Fe/H]
-0.19
Extended Stellar Properties
Surface gravity (log g)
4.680 dex
Stellar density
10.100 g/cm³
Systemic radial velocity
-35.81 km/s
Rotational v·sin i
2.00 km/s
Rotation period
68.00 days
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 7 bands
Astrometric Data
Parallax
33.266 mas
Total Proper Motion
572.211 mas/yr
PM Right Ascension
29.11 mas/yr
PM Declination
-571.47 mas/yr
Galactic Cartesian (pc)
x = 0.005 · y = -0.813 · z = 0.582
Equatorial (J2000)
RA 270.31724° · Dec 35.59490°
Galactic ℓ, b
61.795° · 24.997°
Ecliptic λ, β
270.498° · 59.034°
HTM-20 index
649512617
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