Confirmed Exoplanet Discovered 2026

HD 164604 c

A gas giant orbiting the k-type orange HD 164604, located approximately 128.4 light-years from Earth.

Key parameters at a glance

  • A radius of 12.50 Earth radii
  • A mass of 3,019.37 Earth masses
  • Surface gravity around 19.32 g
  • An orbital period of 5,387.000 days
  • Semi-major axis 5.5560 AU
  • Distance from Earth 128.39 light-years
  • Earth Similarity Index 0.390
  • Travel time at Voyager 1 speed 2,264,083 years

1 sibling around HD 164604

HD 164604 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 164604 b Gas Giant 12.30 4,195.33 653.900 2009
HD 164604 c this Gas Giant 12.50 3,019.37 5,387.000 2026

HD 164604 c Planet Profile

Physical Specs

Radius
12.50 R⊕
Radius (Jupiter)
1.120 R♃
Mass
3,019.37 M⊕
Mass (Jupiter)
9.500 M♃
Density
8.49 g/cm³
Surface Gravity
19.32 g (Earth)

Classification

Planet Type

Gas Giant

ESI Score 0.390
HZ Position Unknown
Controversial No

Discovery

Year 2026
Method Radial Velocity
Facility Las Campanas Observatory
Telescope 6.5 m Magellan II Clay Telescope

Size rank in cohort

Rank by radius

#1235of 1771

top 69.7%

This planet

12.50R⊕

Gas Giant median

13.52R⊕

Nearest-size peers

Metric Earth HD 164604 c Jupiter
Radius (R⊕)1.0012.5011.21
Mass (M⊕)1.003,019.37317.83
Density (g/cm³)5.518.491.33
Surface Gravity (g)1.0019.322.53
Insolation (S⊕)1.000.037

Alternative Mass Estimates

Method Value Interpretation
Best measured mass 3,019.370 M⊕ Direct mass measurement (not derived).

Star Catalogue Identifiers

HD

HD 164604

HIP

HIP 88414

TIC

TIC 406317882

Gaia DR2

Gaia DR2 4062446910648807168

Gaia DR3

Gaia DR3 4062446910648807168

System

HD 164604

Percentile among Gas Giant cohort

Radius 12.500 R⊕ · percentile 28 / cohort 1771
Mass 3,019.370 M⊕ · percentile 87 / cohort 1747
Orbital period 5,387.00 d · percentile 93 / cohort 1533
Distance 39.36 pc · percentile 13 / cohort 1759
ESI 0.390 · percentile 83 / cohort 1771

Orbit & Habitability

Orbital Dynamics

Period
5,387.000 days
Semi-major axis
5.5560 AU
Eccentricity
0.196
Inclination
8.60 °

Year Length

A year here lasts about 14.75 Earth years on a mildly elliptical path at a mean orbital distance of 5.5560 AU.

Eq. Temperature

 

Insolation (S⊕)

Earth = 1.00

Earth Similarity (ESI)

0.390

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

Xiao et al. 2026

Instrument

Carnegie Planet Finder Spectrograph

Publication

2026-02

Observation locale

Ground

Discovery cohort

Planets confirmed in 2026 at Las Campanas Observatory (4 shown).

Host System: HD 164604

Spectral Class

K-type orange

Effective Temperature

4,663 K — cooler than the Sun (5,778 K)

Estimated Age

1.60 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

0.780 R☉

Stellar Mass

0.770 M☉

Metallicity [Fe/H]

0.12

Extended Stellar Properties

Surface gravity (log g)

4.490 dex

Stellar density

2.968 g/cm³

Systemic radial velocity

7.09 km/s

Rotational v·sin i

2.00 km/s

Rotation period

19.00 days

Metallicity ratio

[Fe/H]

Distance
39.36 parsec
Light-years 128.39 ly
V-band magnitude
9.62 mag
Voyager-speed travel 2,264,083 yr

Multi-band Host Photometry — 11 bands

7.110.910.88B9.62V9.33Gaia8.68TESS7.78J7.31H7.17K7.10W17.19W27.20W37.09W4

Astrometric Data

Parallax

25.376 mas

Total Proper Motion

54.272 mas/yr

PM Right Ascension

-34.76 mas/yr

PM Declination

-41.68 mas/yr

Galactic Cartesian (pc)

x = 0.012 · y = -0.878 · z = -0.478

Equatorial (J2000)

RA 270.77872° · Dec -28.56083°

Galactic ℓ, b

2.263° · -3.119°

Ecliptic λ, β

270.683° · -5.123°

HTM-20 index

-1917347018

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