Key parameters at a glance
- A radius of 1.36 Earth radii
- A mass of 3.17 Earth masses
- Surface gravity around 1.71 g
- An orbital period of 10.215 days
- Semi-major axis 0.0675 AU
- Equilibrium temperature 456 K (183 °C)
- Distance from Earth 77.38 light-years
- Earth Similarity Index 0.636
- Travel time at Voyager 1 speed 1,364,674 years
- Almost certainly tidally locked to its host star given the close orbit
TOI-198 b Planet Profile
Physical Specs
Classification
Planet Type
Super-Earth
Discovery
Size rank in cohort
Rank by radius
#981of 1176
top 83.3%
This planet
1.36R⊕
Super-Earth median
1.60R⊕
Nearest-size peers
| Metric | Earth | TOI-198 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 1.36 | 11.21 |
| Mass (M⊕) | 1.00 | 3.17 | 317.83 |
| Density (g/cm³) | 5.51 | 6.89 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.71 | 2.53 |
| Insolation (S⊕) | 1.00 | 7.20 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 3.170 M⊕ | Direct mass measurement (not derived). |
Star Catalogue Identifiers
HIP
HIP 738
TIC
TIC 12421862
Gaia DR2
Gaia DR2 2333676738049780352
Gaia DR3
Gaia DR3 2333676738050041728
System
TOI-198
Percentile among Super-Earth cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 10.22 Earth days (2.8% of a terrestrial year) on a mildly elliptical path at a mean orbital distance of 0.0675 AU.
Transit Fingerprint
Depth
0.089 %
Duration
2.260 h
Impact parameter b
0.220
Rp / R★
0.029880
Transit midpoint (BJD)
2,459,480.0480
Photometric dip
Transit produces a flux drop of 893 ppm lasting ≈ 2.26 h.
Extended Orbital Architecture
Planet / star radius ratio
0.029880
Semi-major axis / stellar radius
34.690
Impact parameter (b)
0.220
RV semi-amplitude (K)
1.673 m/s
Transit mid-time (BJD)
2,459,480.0480
Long. of periastron (ω)
90.00°
Angular separation (arcsec)
2.84000
Eq. Temperature
456K
(183 °C)
Insolation (S⊕)
7.20
Earth = 1.00
Earth Similarity (ESI)
0.636
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
Oddo et al. 2023Instrument
TESS CCD Array
Publication
2023-03
Observation locale
Space
Discovery cohort
Planets confirmed in 2023 at Transiting Exoplanet Survey Satellite (TESS) (12 shown).
Host System: TOI-198
Spectral Class
M-type red dwarf
Effective Temperature
3,801 K — cooler than the Sun (5,778 K)
Estimated Age
1.00 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
0.418 R☉
Stellar Mass
0.417 M☉
Metallicity [Fe/H]
-0.66
Extended Stellar Properties
Surface gravity (log g)
4.810 dex
Stellar density
6.988 g/cm³
Systemic radial velocity
19.70 km/s
Rotation period
48.50 days
Activity index (log R'HK)
-5.355
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 8 bands
Astrometric Data
Parallax
42.119 mas
Total Proper Motion
698.099 mas/yr
PM Right Ascension
692.26 mas/yr
PM Declination
90.14 mas/yr
Galactic Cartesian (pc)
x = 0.889 · y = 0.035 · z = -0.456
Equatorial (J2000)
RA 2.27151° · Dec -27.12175°
Galactic ℓ, b
30.552° · -80.579°
Ecliptic λ, β
350.487° · -25.613°
HTM-20 index
-1225376693
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