Key parameters at a glance
- A radius of 15.61 Earth radii
- A mass of 238.05 Earth masses
- Surface gravity around 0.98 g
- An orbital period of 3.923 days
- Semi-major axis 0.0529 AU
- Equilibrium temperature 1,540 K (1267 °C)
- Distance from Earth 1,484.67 light-years
- Earth Similarity Index 0.071
- Travel time at Voyager 1 speed 26,182,187 years
HAT-P-9 b Planet Profile
Physical Specs
Classification
Planet Type
Gas Giant
Discovery
Size rank in cohort
Rank by radius
#191of 1771
top 10.7%
This planet
15.61R⊕
Gas Giant median
13.52R⊕
Nearest-size peers
| Metric | Earth | HAT-P-9 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 15.61 | 11.21 |
| Mass (M⊕) | 1.00 | 238.05 | 317.83 |
| Density (g/cm³) | 5.51 | 0.34 | 1.33 |
| Surface Gravity (g) | 1.00 | 0.98 | 2.53 |
| Insolation (S⊕) | 1.00 | 931.00 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 238.055 M⊕ | Direct mass measurement (not derived). |
| Minimum mass (M sin i) | 237.737 M⊕ | Lower bound from radial-velocity fitting. |
| Computed mass | 238.196 M⊕ | Model-computed mass (e.g. from mass-radius relation). |
Star Catalogue Identifiers
TIC
TIC 371234684
Gaia DR2
Gaia DR2 898130030131443584
Gaia DR3
Gaia DR3 898130030131443584
System
HAT-P-9
Percentile among Gas Giant cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 3.92 Earth days (1.1% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0529 AU.
Transit Fingerprint
Depth
1.144 %
Duration
3.360 h
Impact parameter b
0.510
Rp / R★
0.106960
Transit midpoint (BJD)
2,455,484.9131
Photometric dip
Transit produces a flux drop of 11,440 ppm lasting ≈ 3.36 h.
Extended Orbital Architecture
Planet / star radius ratio
0.106960
Semi-major axis / stellar radius
8.500
Impact parameter (b)
0.510
RV semi-amplitude (K)
82.100 m/s
Transit mid-time (BJD)
2,455,484.9131
Long. of periastron (ω)
152.00°
Sky-projected obliquity (λ)
-16.00°
Angular separation (arcsec)
0.11600
Eq. Temperature
1,540K
(1267 °C)
Insolation (S⊕)
931.00
Earth = 1.00
Earth Similarity (ESI)
0.071
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
Shporer et al. 2009Instrument
2K CCD Sensor
Publication
2009-01
Observation locale
Ground
Discovery cohort
Planets confirmed in 2008 at HATNet (3 shown).
Host System: HAT-P-9
Spectral Class
F-type yellow-white
Effective Temperature
6,350 K — hotter than the Sun (5,778 K)
Estimated Age
1.60 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
1.338 R☉
Stellar Mass
1.281 M☉
Metallicity [Fe/H]
0.12
Extended Stellar Properties
Surface gravity (log g)
4.293 dex
Stellar density
0.755 g/cm³
Systemic radial velocity
22.67 km/s
Rotational v·sin i
11.90 km/s
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 16 bands
Astrometric Data
Parallax
2.169 mas
Total Proper Motion
16.213 mas/yr
PM Right Ascension
-9.63 mas/yr
PM Declination
-13.04 mas/yr
Galactic Cartesian (pc)
x = -0.275 · y = 0.748 · z = 0.604
Equatorial (J2000)
RA 110.16852° · Dec 37.14059°
Galactic ℓ, b
181.087° · 21.443°
Ecliptic λ, β
106.516° · 14.851°
HTM-20 index
1633637524
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