Key parameters at a glance
- A radius of 7.90 Earth radii
- A mass of 44.00 Earth masses
- Surface gravity around 0.71 g
- An orbital period of 4.353 days
- Semi-major axis 0.0410 AU
- Equilibrium temperature 563 K (290 °C)
- Distance from Earth 355.13 light-years
- Earth Similarity Index 0.264
- Travel time at Voyager 1 speed 6,262,690 years
- Almost certainly tidally locked to its host star given the close orbit
TOI-3984 A b Planet Profile
Physical Specs
Classification
Planet Type
Neptune-like
Discovery
Size rank in cohort
Rank by radius
#160of 574
top 27.7%
This planet
7.90R⊕
Neptune-like median
6.39R⊕
Nearest-size peers
| Metric | Earth | TOI-3984 A b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 7.90 | 11.21 |
| Mass (M⊕) | 1.00 | 44.00 | 317.83 |
| Density (g/cm³) | 5.51 | 0.49 | 1.33 |
| Surface Gravity (g) | 1.00 | 0.71 | 2.53 |
| Insolation (S⊕) | 1.00 | 16.70 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 44.000 M⊕ | Direct mass measurement (not derived). |
Star Catalogue Identifiers
TIC
TIC 20182780
Gaia DR2
Gaia DR2 1291955578869575552
Gaia DR3
Gaia DR3 1291955578869575552
System
TOI-3984
Percentile among Neptune-like cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 4.35 Earth days (1.2% of a terrestrial year) on a mildly elliptical path at a mean orbital distance of 0.0410 AU.
Transit Fingerprint
Depth
2.174 %
Duration
2.010 h
Impact parameter b
0.180
Rp / R★
0.155800
Transit midpoint (BJD)
2,459,715.0227
Photometric dip
Transit produces a flux drop of 21,740 ppm lasting ≈ 2.01 h.
Extended Orbital Architecture
Planet / star radius ratio
0.155800
Semi-major axis / stellar radius
19.100
Impact parameter (b)
0.180
RV semi-amplitude (K)
27.700 m/s
Transit mid-time (BJD)
2,459,715.0227
Long. of periastron (ω)
-54.00°
Angular separation (arcsec)
0.37700
Eq. Temperature
563K
(290 °C)
Insolation (S⊕)
16.70
Earth = 1.00
Earth Similarity (ESI)
0.264
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
Ca Ntilde As et al. 2023Instrument
TESS CCD Array
Publication
2023-07
Observation locale
Space
Discovery cohort
Planets confirmed in 2023 at Transiting Exoplanet Survey Satellite (TESS) (12 shown).
Host System: TOI-3984 A
Spectral Class
M-type red dwarf
Effective Temperature
3,476 K — cooler than the Sun (5,778 K)
Estimated Age
2.90 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
0.470 R☉
Stellar Mass
0.490 M☉
Metallicity [Fe/H]
0.18
Extended Stellar Properties
Surface gravity (log g)
4.810 dex
Stellar density
6.900 g/cm³
Systemic radial velocity
-5.77 km/s
Rotational v·sin i
2.00 km/s
Rotation period
50.00 days
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 16 bands
Astrometric Data
Parallax
9.155 mas
Total Proper Motion
64.936 mas/yr
PM Right Ascension
-48.94 mas/yr
PM Declination
42.69 mas/yr
Galactic Cartesian (pc)
x = -0.553 · y = -0.579 · z = 0.599
Equatorial (J2000)
RA 226.33715° · Dec 36.78697°
Galactic ℓ, b
60.268° · 60.178°
Ecliptic λ, β
207.943° · 51.250°
HTM-20 index
1842854732
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