Key parameters at a glance
- A radius of 13.20 Earth radii
- A mass of 899.45 Earth masses
- Surface gravity around 5.16 g
- An orbital period of 1,708.000 days
- Semi-major axis 2.8145 AU
- Distance from Earth 123.44 light-years
- Earth Similarity Index 0.392
- Travel time at Voyager 1 speed 2,176,915 years
1 sibling around HD 12661
HD 12661 c shares its host star with 1 other confirmed planet. Side-by-side measurements below.
| Planet | Type | Radius (R⊕) | Mass (M⊕) | Period (d) | Eq. T (K) | Year |
|---|---|---|---|---|---|---|
| HD 12661 b | Gas Giant | 13.30 | 772.33 | 262.709 | — | 2000 |
| HD 12661 c this | Gas Giant | 13.20 | 899.45 | 1,708.000 | — | 2002 |
HD 12661 c Planet Profile
Physical Specs
Classification
Planet Type
Gas Giant
Discovery
Size rank in cohort
Rank by radius
#847of 1771
top 47.8%
This planet
13.20R⊕
Gas Giant median
13.52R⊕
Nearest-size peers
| Metric | Earth | HD 12661 c | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 13.20 | 11.21 |
| Mass (M⊕) | 1.00 | 899.45 | 317.83 |
| Density (g/cm³) | 5.51 | 2.15 | 1.33 |
| Surface Gravity (g) | 1.00 | 5.16 | 2.53 |
| Insolation (S⊕) | 1.00 | — | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 899.454 M⊕ | Direct mass measurement (not derived). |
| Minimum mass (M sin i) | 575.884 M⊕ | Lower bound from radial-velocity fitting. |
Star Catalogue Identifiers
HD
HD 12661
HIP
HIP 9683
TIC
TIC 118268680
Gaia DR2
Gaia DR2 105332908999068032
Gaia DR3
Gaia DR3 105332908999068032
System
HD 12661
Percentile among Gas Giant cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts about 4.68 Earth years on a nearly circular orbit at a mean orbital distance of 2.8145 AU.
Extended Orbital Architecture
RV semi-amplitude (K)
30.410 m/s
Transit mid-time (BJD)
2,455,774.9000
Long. of periastron (ω)
60.00°
Angular separation (arcsec)
74.40000
Eq. Temperature
—
Insolation (S⊕)
—
Earth = 1.00
Earth Similarity (ESI)
0.392
0 = alien, 1 = Earth-identical
Detection Signatures
Radial velocity
Stellar wobble has been measured spectroscopically.
Astrometry
Positional wobble of the host star was measured.
Discovery Paper
Primary reference
Fischer et al. 2003Instrument
Multiple Instruments
Publication
2003-04
Observation locale
Ground
Discovery cohort
Planets confirmed in 2002 at Multiple Observatories (2 shown).
Host System: HD 12661
Spectral Class
K-type orange
Effective Temperature
5,748 K — cooler than the Sun (5,778 K)
Estimated Age
6.39 Gyr — older than the Sun (4.6 Gyr)
Stellar Radius
1.110 R☉
Stellar Mass
1.020 M☉
Metallicity [Fe/H]
0.36
Extended Stellar Properties
Surface gravity (log g)
4.316 dex
Stellar density
0.788 g/cm³
Systemic radial velocity
-47.38 km/s
Rotational v·sin i
1.30 km/s
Activity index (log R'HK)
-5.080
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 11 bands
Astrometric Data
Parallax
26.393 mas
Total Proper Motion
204.324 mas/yr
PM Right Ascension
-108.18 mas/yr
PM Declination
-173.34 mas/yr
Galactic Cartesian (pc)
x = 0.773 · y = 0.467 · z = 0.429
Equatorial (J2000)
RA 31.14235° · Dec 25.41356°
Galactic ℓ, b
143.063° · -34.583°
Ecliptic λ, β
37.779° · 12.001°
HTM-20 index
-514195101
Observation Record
Photometric series
1
RV measurements
8
Stellar spectra
3
Archive notes
1
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