HD 20781 is 117 light-years from the Sun. The NASA Exoplanet Archive lists 4 planets around this K0 V star; the first was found in 2019 by radial velocity (La Silla Observatory).
Fly there in 3DHD 20781 b goes round its star every 5.31 days, 17 times as often as Mercury goes round the Sun.
HD 20781 is one of 2 stars in its system: the other is drawn where the Washington Double Star Catalog measures it on the sky.
| Spectral type | K0 V |
| Surface temperature | 5,256 K |
| Mass | 0.7 solar masses |
| Radius | 0.833609 solar radii |
| Luminosity | 0.49 times the Sun |
| Apparent magnitude | 8.48 |
| Distance from the Sun | 117.3 light-years (36.0 parsecs) |
| Position (J2000) | RA 50.0140°, Dec -28.7841° |
| Constellation | Fornax |
HD 20781 A is a G1.5V star of magnitude 7.44, moving through space with it. In 2016 it was 253″ from HD 20781, at position angle 178° (Washington Double Star Catalog, 03201-2851 LDS 93): 9,101 AU on the sky at this distance. The true distance can only be larger.
| Planet | Year | Orbit | Radius | Mass | Found |
|---|---|---|---|---|---|
| HD 20781 b | 5.31 days | 0.0529 AU | 1.21 R⊕ estimated | 1.93 M⊕ minimum | Radial Velocity, 2019 |
| HD 20781 c | 13.9 days | 0.100 AU | 2.17 R⊕ estimated | 5.33 M⊕ minimum | Radial Velocity, 2019 |
| HD 20781 d | 29.2 days | 0.165 AU | 3.25 R⊕ estimated | 10.61 M⊕ minimum | Radial Velocity, 2019 |
| HD 20781 e | 85.5 days | 0.337 AU | 3.83 R⊕ estimated | 14.03 M⊕ minimum | Radial Velocity, 2019 |
Values are the NASA Exoplanet Archive’s composite parameters. A radius marked estimated comes from a mass–radius relation; a mass marked minimum is M sin i. Planet sizes and colours in the 3D view are renderings: none of these worlds has been photographed as more than a point of light.