Key parameters at a glance
- A radius of 20.29 Earth radii
- A mass of 527.60 Earth masses
- Surface gravity around 1.28 g
- An orbital period of 3.345 days
- Semi-major axis 0.0558 AU
- Equilibrium temperature 2,470 K (2197 °C)
- Distance from Earth 1,394.90 light-years
- Earth Similarity Index 0.038
- Travel time at Voyager 1 speed 24,599,015 years
WASP-178 b Planet Profile
Physical Specs
Classification
Planet Type
Gas Giant
Discovery
Size rank in cohort
Rank by radius
#29of 1771
top 1.6%
This planet
20.29R⊕
Gas Giant median
13.52R⊕
Nearest-size peers
| Metric | Earth | WASP-178 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 20.29 | 11.21 |
| Mass (M⊕) | 1.00 | 527.60 | 317.83 |
| Density (g/cm³) | 5.51 | 0.37 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.28 | 2.53 |
| Insolation (S⊕) | 1.00 | 5,550.00 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 527.598 M⊕ | Direct mass measurement (not derived). |
| Minimum mass (M sin i) | 444.962 M⊕ | Lower bound from radial-velocity fitting. |
| Computed mass | 447.058 M⊕ | Model-computed mass (e.g. from mass-radius relation). |
Star Catalogue Identifiers
HD
HD 134004
TIC
TIC 160708862
Gaia DR2
Gaia DR2 6003809889735481856
Gaia DR3
Gaia DR3 6003809889735481856
System
WASP-178
Percentile among Gas Giant cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 3.34 Earth days (0.9% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0558 AU.
Transit Fingerprint
Depth
1.243 %
Duration
3.470 h
Impact parameter b
0.540
Rp / R★
0.110660
Transit midpoint (BJD)
2,456,927.0684
Photometric dip
Transit produces a flux drop of 12,430 ppm lasting ≈ 3.47 h.
Extended Orbital Architecture
Planet / star radius ratio
0.110660
Semi-major axis / stellar radius
7.170
Impact parameter (b)
0.540
RV semi-amplitude (K)
139.000 m/s
Transit mid-time (BJD)
2,456,927.0684
Sky-projected obliquity (λ)
91.30°
Angular separation (arcsec)
0.13000
Eq. Temperature
2,470K
(2197 °C)
Insolation (S⊕)
5,550.00
Earth = 1.00
Earth Similarity (ESI)
0.038
0 = alien, 1 = Earth-identical
Inside the inner HZ boundary (too hot for liquid water) — the dayside is scorched.
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
Hellier et al. 2019Instrument
iKon-L CCD Camera
Publication
2019-11
Observation locale
Ground
Discovery cohort
Planets confirmed in 2019 at WASP-South (9 shown).
Host System: WASP-178
Spectral Class
A-type white
Effective Temperature
9,360 K — hotter than the Sun (5,778 K)
Estimated Age
0.43 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
1.670 R☉
Stellar Mass
2.070 M☉
Metallicity [Fe/H]
0.21
Extended Stellar Properties
Surface gravity (log g)
4.310 dex
Stellar density
0.620 g/cm³
Systemic radial velocity
-23.91 km/s
Rotational v·sin i
8.20 km/s
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 11 bands
Astrometric Data
Parallax
2.312 mas
Total Proper Motion
11.497 mas/yr
PM Right Ascension
-10.01 mas/yr
PM Declination
-5.65 mas/yr
Galactic Cartesian (pc)
x = -0.499 · y = -0.540 · z = -0.678
Equatorial (J2000)
RA 227.27033° · Dec -42.70497°
Galactic ℓ, b
328.194° · 13.315°
Ecliptic λ, β
236.901° · -24.050°
HTM-20 index
1509332887
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