Key parameters at a glance
- A radius of 10.75 Earth radii
- A mass of 67.06 Earth masses
- Surface gravity around 0.58 g
- An orbital period of 3.213 days
- Semi-major axis 0.0384 AU
- Equilibrium temperature 963 K (690 °C)
- Distance from Earth 465.59 light-years
- Earth Similarity Index 0.132
- Travel time at Voyager 1 speed 8,210,696 years
- Almost certainly tidally locked to its host star given the close orbit
HAT-P-12 b Planet Profile
Physical Specs
Classification
Planet Type
Gas Giant
Discovery
Size rank in cohort
Rank by radius
#1702of 1771
top 96.0%
This planet
10.75R⊕
Gas Giant median
13.52R⊕
Nearest-size peers
| Metric | Earth | HAT-P-12 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 10.75 | 11.21 |
| Mass (M⊕) | 1.00 | 67.06 | 317.83 |
| Density (g/cm³) | 5.51 | 0.32 | 1.33 |
| Surface Gravity (g) | 1.00 | 0.58 | 2.53 |
| Insolation (S⊕) | 1.00 | 118.08 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 67.059 M⊕ | Direct mass measurement (not derived). |
| Minimum mass (M sin i) | 66.109 M⊕ | Lower bound from radial-velocity fitting. |
Star Catalogue Identifiers
TIC
TIC 198108326
Gaia DR2
Gaia DR2 1499514786891168640
Gaia DR3
Gaia DR3 1499514786891168640
System
HAT-P-12
Percentile among Gas Giant cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 3.21 Earth days (0.9% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0384 AU.
Transit Fingerprint
Depth
1.977 %
Duration
2.338 h
Impact parameter b
0.211
Rp / R★
0.140600
Transit midpoint (BJD)
2,454,419.1956
Photometric dip
Transit produces a flux drop of 19,770 ppm lasting ≈ 2.34 h.
Extended Orbital Architecture
Planet / star radius ratio
0.140600
Semi-major axis / stellar radius
11.770
Impact parameter (b)
0.211
RV semi-amplitude (K)
35.800 m/s
Transit mid-time (BJD)
2,454,419.1956
Long. of periastron (ω)
354.30°
Sky-projected obliquity (λ)
-54.00°
Angular separation (arcsec)
0.26900
Eq. Temperature
963K
(690 °C)
Insolation (S⊕)
118.08
Earth = 1.00
Earth Similarity (ESI)
0.132
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
Hartman et al. 2009Instrument
2K CCD Sensor
Publication
2009-11
Observation locale
Ground
Host System: HAT-P-12
Spectral Class
K-type orange
Effective Temperature
4,650 K — cooler than the Sun (5,778 K)
Estimated Age
2.50 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
0.701 R☉
Stellar Mass
0.733 M☉
Metallicity [Fe/H]
-0.29
Extended Stellar Properties
Surface gravity (log g)
4.610 dex
Stellar density
3.109 g/cm³
Systemic radial velocity
-40.51 km/s
Rotational v·sin i
0.50 km/s
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 16 bands
Astrometric Data
Parallax
6.976 mas
Total Proper Motion
141.882 mas/yr
PM Right Ascension
-134.79 mas/yr
PM Declination
-44.29 mas/yr
Galactic Cartesian (pc)
x = -0.632 · y = -0.356 · z = 0.688
Equatorial (J2000)
RA 209.38865° · Dec 43.49331°
Galactic ℓ, b
87.993° · 68.876°
Ecliptic λ, β
184.775° · 50.632°
HTM-20 index
1870254252
Observation Record
Photometric series
7
RV measurements
1
Transmission spectra
18
Emission spectra
4
Archive notes
1
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