Key parameters at a glance
- A radius of 12.22 Earth radii
- A mass of 5,879.83 Earth masses
- Surface gravity around 39.39 g
- An orbital period of 14.476 days
- Semi-major axis 0.0950 AU
- Equilibrium temperature 408 K (135 °C)
- Distance from Earth 246.50 light-years
- Earth Similarity Index 0.313
- Travel time at Voyager 1 speed 4,346,945 years
- Almost certainly tidally locked to its host star given the close orbit
TOI-1278 b Planet Profile
Physical Specs
Classification
Planet Type
Gas Giant
Discovery
Size rank in cohort
Rank by radius
#1408of 1771
top 79.4%
This planet
12.22R⊕
Gas Giant median
13.52R⊕
Nearest-size peers
| Metric | Earth | TOI-1278 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 12.22 | 11.21 |
| Mass (M⊕) | 1.00 | 5,879.83 | 317.83 |
| Density (g/cm³) | 5.51 | 18.00 | 1.33 |
| Surface Gravity (g) | 1.00 | 39.39 | 2.53 |
| Insolation (S⊕) | 1.00 | 6.54 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 5,879.826 M⊕ | Direct mass measurement (not derived). |
Star Catalogue Identifiers
TIC
TIC 163539739
Gaia DR2
Gaia DR2 1867491607542113536
Gaia DR3
Gaia DR3 1867491607542113536
System
TOI-1278
Percentile among Gas Giant cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 14.48 Earth days (4.0% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0950 AU.
Transit Fingerprint
Depth
0.962 %
Duration
1.618 h
Impact parameter b
1.040
Transit midpoint (BJD)
2,458,711.9595
Photometric dip
Transit produces a flux drop of 9,619 ppm lasting ≈ 1.62 h.
Extended Orbital Architecture
Impact parameter (b)
1.040
RV semi-amplitude (K)
2,306.000 m/s
Transit mid-time (BJD)
2,458,711.9595
Long. of periastron (ω)
246.00°
Angular separation (arcsec)
1.26000
Eq. Temperature
408K
(135 °C)
Insolation (S⊕)
6.54
Earth = 1.00
Earth Similarity (ESI)
0.313
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
Artigau et al. 2021Instrument
TESS CCD Array
Publication
2021-10
Observation locale
Space
Discovery cohort
Planets confirmed in 2021 at Transiting Exoplanet Survey Satellite (TESS) (12 shown).
Host System: TOI-1278
Spectral Class
M-type red dwarf
Effective Temperature
3,799 K — cooler than the Sun (5,778 K)
Estimated Age
—
Stellar Radius
0.573 R☉
Stellar Mass
0.540 M☉
Metallicity [Fe/H]
-0.01
Extended Stellar Properties
Surface gravity (log g)
4.680 dex
Stellar density
4.614 g/cm³
Systemic radial velocity
-29.33 km/s
Rotational v·sin i
1.10 km/s
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 11 bands
Astrometric Data
Parallax
13.203 mas
Total Proper Motion
101.078 mas/yr
PM Right Ascension
-89.56 mas/yr
PM Declination
-46.87 mas/yr
Galactic Cartesian (pc)
x = 0.627 · y = -0.517 · z = 0.583
Equatorial (J2000)
RA 320.47844° · Dec 35.64863°
Galactic ℓ, b
82.101° · -10.119°
Ecliptic λ, β
338.837° · 47.767°
HTM-20 index
-1289926706
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