Key parameters at a glance
- A radius of 14.28 Earth radii
- A mass of 213.26 Earth masses
- Surface gravity around 1.05 g
- An orbital period of 3.057 days
- Semi-major axis 0.0444 AU
- Equilibrium temperature 1,686 K (1413 °C)
- Distance from Earth 1,045.17 light-years
- Earth Similarity Index 0.067
- Travel time at Voyager 1 speed 18,431,575 years
HAT-P-4 b Planet Profile
Physical Specs
Classification
Planet Type
Gas Giant
Discovery
Size rank in cohort
Rank by radius
#326of 1771
top 18.4%
This planet
14.28R⊕
Gas Giant median
13.52R⊕
Nearest-size peers
| Metric | Earth | HAT-P-4 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 14.28 | 11.21 |
| Mass (M⊕) | 1.00 | 213.26 | 317.83 |
| Density (g/cm³) | 5.51 | 0.40 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.05 | 2.53 |
| Insolation (S⊕) | 1.00 | 1,438.00 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 213.255 M⊕ | Direct mass measurement (not derived). |
| Minimum mass (M sin i) | 208.179 M⊕ | Lower bound from radial-velocity fitting. |
Star Catalogue Identifiers
TIC
TIC 138294130
Gaia DR2
Gaia DR2 1291120362349158016
Gaia DR3
Gaia DR3 1291120362349158016
System
HAT-P-4
Percentile among Gas Giant cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 3.06 Earth days (0.8% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0444 AU.
Transit Fingerprint
Depth
0.780 %
Duration
4.224 h
Impact parameter b
0.010
Rp / R★
0.082000
Transit midpoint (BJD)
2,455,584.5724
Photometric dip
Transit produces a flux drop of 7,798 ppm lasting ≈ 4.22 h.
Extended Orbital Architecture
Planet / star radius ratio
0.082000
Semi-major axis / stellar radius
6.040
Impact parameter (b)
0.010
RV semi-amplitude (K)
81.100 m/s
Transit mid-time (BJD)
2,455,584.5724
Long. of periastron (ω)
97.40°
Sky-projected obliquity (λ)
-4.90°
Angular separation (arcsec)
0.13800
Eq. Temperature
1,686K
(1413 °C)
Insolation (S⊕)
1,438.00
Earth = 1.00
Earth Similarity (ESI)
0.067
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
Kovacs et al. 2007Instrument
2K CCD Sensor
Publication
2007-11
Observation locale
Ground
Discovery cohort
Planets confirmed in 2007 at HATNet (4 shown).
Host System: HAT-P-4
Spectral Class
F-type yellow-white
Effective Temperature
5,860 K — hotter than the Sun (5,778 K)
Estimated Age
3.90 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
1.596 R☉
Stellar Mass
1.248 M☉
Metallicity [Fe/H]
0.24
Extended Stellar Properties
Surface gravity (log g)
4.127 dex
Stellar density
0.437 g/cm³
Systemic radial velocity
-1.58 km/s
Rotational v·sin i
5.83 km/s
Multi-band Host Photometry — 11 bands
Astrometric Data
Parallax
3.092 mas
Total Proper Motion
32.515 mas/yr
PM Right Ascension
-21.66 mas/yr
PM Declination
-24.25 mas/yr
Galactic Cartesian (pc)
x = -0.519 · y = -0.618 · z = 0.591
Equatorial (J2000)
RA 229.99122° · Dec 36.22955°
Galactic ℓ, b
58.480° · 57.336°
Ecliptic λ, β
212.605° · 52.001°
HTM-20 index
-1462780478
Observation Record
Photometric series
10
RV measurements
1
Emission spectra
4
Archive notes
1
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