Key parameters at a glance
- A radius of 2.91 Earth radii
- A mass of 1,112.40 Earth masses
- Surface gravity around 131.36 g
- An orbital period of 91.683 days
- Semi-major axis 0.3870 AU
- Equilibrium temperature 440 K (167 °C)
- Distance from Earth 451.44 light-years
- Earth Similarity Index 0.331
- Travel time at Voyager 1 speed 7,961,070 years
TOI-1221 b Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#608of 1978
top 30.7%
This planet
2.91R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | TOI-1221 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 2.91 | 11.21 |
| Mass (M⊕) | 1.00 | 1,112.40 | 317.83 |
| Density (g/cm³) | 5.51 | — | 1.33 |
| Surface Gravity (g) | 1.00 | 131.36 | 2.53 |
| Insolation (S⊕) | 1.00 | 6.06 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 1,112.399 M⊕ | Direct mass measurement (not derived). |
Star Catalogue Identifiers
TIC
TIC 349095149
Gaia DR2
Gaia DR2 5282270089967734912
Gaia DR3
Gaia DR3 5282270085669557504
System
TOI-1221
Percentile among Sub-Neptune cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 91.68 Earth days (25.1% of a terrestrial year) on a mildly elliptical path at a mean orbital distance of 0.3870 AU.
Transit Fingerprint
Depth
0.072 %
Duration
8.120 h
Impact parameter b
0.250
Rp / R★
0.026790
Transit midpoint (BJD)
2,458,404.1791
Photometric dip
Transit produces a flux drop of 720 ppm lasting ≈ 8.12 h.
Extended Orbital Architecture
Planet / star radius ratio
0.026790
Semi-major axis / stellar radius
83.700
Impact parameter (b)
0.250
Transit mid-time (BJD)
2,458,404.1791
Angular separation (arcsec)
2.80000
Eq. Temperature
440K
(167 °C)
Insolation (S⊕)
6.06
Earth = 1.00
Earth Similarity (ESI)
0.331
0 = alien, 1 = Earth-identical
Inside the inner HZ boundary (too hot for liquid water) — the surface is too hot to retain surface water.
Detection Signatures
Transit photometry
A transit dip has been observed from at least one telescope.
Transit timing variations
Gravitational interactions from neighbours have been detected.
Discovery Paper
Primary reference
Mann et al. 2023Instrument
TESS CCD Array
Publication
2023-05
Observation locale
Space
Discovery cohort
Planets confirmed in 2023 at Transiting Exoplanet Survey Satellite (TESS) (12 shown).
Host System: TOI-1221
Spectral Class
G-type yellow (Sun-like)
Effective Temperature
5,592 K — cooler than the Sun (5,778 K)
Estimated Age
10.00 Gyr — older than the Sun (4.6 Gyr)
Stellar Radius
1.031 R☉
Stellar Mass
0.930 M☉
Metallicity [Fe/H]
0.06
Extended Stellar Properties
Surface gravity (log g)
4.380 dex
Stellar density
1.320 g/cm³
Rotational v·sin i
2.10 km/s
Activity index (log R'HK)
-5.200
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 11 bands
Astrometric Data
Parallax
7.196 mas
Total Proper Motion
39.510 mas/yr
PM Right Ascension
0.47 mas/yr
PM Declination
39.51 mas/yr
Galactic Cartesian (pc)
x = -0.128 · y = 0.394 · z = -0.910
Equatorial (J2000)
RA 107.92103° · Dec -65.50886°
Galactic ℓ, b
276.387° · -22.483°
Ecliptic λ, β
180.039° · -82.671°
HTM-20 index
1271731117
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