Key parameters at a glance
- A radius of 14.84 Earth radii
- A mass of 189.43 Earth masses
- Surface gravity around 0.86 g
- An orbital period of 3.585 days
- Semi-major axis 0.0463 AU
- Equilibrium temperature 1,367 K (1094 °C)
- Distance from Earth 1,667.92 light-years
- Earth Similarity Index 0.082
- Travel time at Voyager 1 speed 29,413,814 years
HAT-P-55 b Planet Profile
Physical Specs
Classification
Planet Type
Gas Giant
Discovery
Size rank in cohort
Rank by radius
#248of 1771
top 13.9%
This planet
14.84R⊕
Gas Giant median
13.52R⊕
Nearest-size peers
| Metric | Earth | HAT-P-55 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 14.84 | 11.21 |
| Mass (M⊕) | 1.00 | 189.43 | 317.83 |
| Density (g/cm³) | 5.51 | 0.32 | 1.33 |
| Surface Gravity (g) | 1.00 | 0.86 | 2.53 |
| Insolation (S⊕) | 1.00 | 583.00 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 189.426 M⊕ | Direct mass measurement (not derived). |
Star Catalogue Identifiers
TIC
TIC 311408969
Gaia DR2
Gaia DR2 4593808272896243328
Gaia DR3
Gaia DR3 4593808272896243328
System
HAT-P-55
Percentile among Gas Giant cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 3.59 Earth days (1.0% of a terrestrial year) on a mildly elliptical path at a mean orbital distance of 0.0463 AU.
Transit Fingerprint
Depth
1.691 %
Duration
2.935 h
Impact parameter b
0.392
Rp / R★
0.122000
Transit midpoint (BJD)
2,458,311.9226
Photometric dip
Transit produces a flux drop of 16,909 ppm lasting ≈ 2.94 h.
Extended Orbital Architecture
Planet / star radius ratio
0.122000
Semi-major axis / stellar radius
9.060
Impact parameter (b)
0.392
RV semi-amplitude (K)
77.600 m/s
Transit mid-time (BJD)
2,458,311.9226
Angular separation (arcsec)
0.09050
Eq. Temperature
1,367K
(1094 °C)
Insolation (S⊕)
583.00
Earth = 1.00
Earth Similarity (ESI)
0.082
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
Juncher et al. 2015Instrument
2K CCD Sensor
Publication
2015-09
Observation locale
Ground
Discovery cohort
Planets confirmed in 2015 at HATNet (7 shown).
Host System: HAT-P-55
Spectral Class
G-type yellow (Sun-like)
Effective Temperature
5,804 K — hotter than the Sun (5,778 K)
Estimated Age
5.30 Gyr — older than the Sun (4.6 Gyr)
Stellar Radius
1.105 R☉
Stellar Mass
1.028 M☉
Metallicity [Fe/H]
0.00
Extended Stellar Properties
Surface gravity (log g)
4.363 dex
Stellar density
1.073 g/cm³
Systemic radial velocity
-9.42 km/s
Rotational v·sin i
1.80 km/s
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 15 bands
Astrometric Data
Parallax
1.927 mas
Total Proper Motion
10.978 mas/yr
PM Right Ascension
7.39 mas/yr
PM Declination
-8.12 mas/yr
Galactic Cartesian (pc)
x = -0.090 · y = -0.896 · z = 0.434
Equatorial (J2000)
RA 264.27351° · Dec 25.73115°
Galactic ℓ, b
49.588° · 26.969°
Ecliptic λ, β
262.119° · 49.014°
HTM-20 index
1798955248
Similar Worlds
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Radius 14.83 R⊕ · 411.8 ly
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WASP-36 b
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NGTS-26 b
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Radius 14.78 R⊕ · 518.5 ly