Gas giant · HD 181720

HD 181720 b

ExoplanetsDiscovered 2009

Scientific overview

HD 181720 b is a gas giant orbiting HD 181720, completing an orbit every 956 days, about 196 light-years from Earth. It was discovered in 2009 using the radial velocity method.

Host star

Sika

Spectral type

G1 V

Temperature

5,736 K

Mass

1.03 M☉

Discovery and detection

Detection method

Radial Velocity Method

Discovery year

2009

Discovered at

La Silla Observatory

Knowledge connections

OrbitsSika
Discovered by methodRadial Velocity Method
Discovered atLa Silla Observatory
Catalogued inNASA Exoplanet Archive

Quick facts

Class: Gas giant
Host star: Sika
Discovery method: Radial Velocity Method
Discovery year: 2009
Orbital period: 956 d
Semi-major axis: 1.85 AU
Eccentricity: 0.26
Radius: 14 R⊕
Mass: 127.13 M⊕
Density: 0.26 g/cm³ · derived
Equilibrium temp.: 249 K
Insolation: 0.57 S⊕
Distance: 196 ly

Density is derived from the archive mass and radius via ρ = M / (4⁄3·π·r³); all other values are catalogued measurements.

Derived values

Computed from source-backed inputs via standard formulae — not observations. Every input and constant is traced below.

Bulk density0.26 g/cm³derived
Formula & inputs
Formula: ρ = M / (4⁄3·π·r³) (v1.0.0, impl v1.0.0)
Inputs:
- massEarth = 127.13 M⊕ · NASA
- radiusEarth = 14 R⊕ · NASA
Assumptions: M⊕ = 5.972e+24 kg, R⊕ = 6371000 m (IAU 2015 B3 nominal); Assumes a uniform sphere.
Limitations: Withheld above 30 g/cm³ (inconsistent mass/radius inputs).; Archive mass/radius carry no propagated uncertainty here.
Uncertainty: not propagated (inputs carry no catalogued uncertainty)
Computed as of 2026-06-29.

Quality & authority

Partial

Unreviewed

Description: Complete
Source coverage: Partial
Relationship coverage: Complete
Review coverage: None
Citation coverage: None
Image coverage: Not applicable

Data from the NASA Exoplanet Archive. See source quality.