GJ 3998 is 59.2 light-years from the Sun. The NASA Exoplanet Archive lists 3 planets around this M1 star; the first was found in 2016 by radial velocity (Roque de los Muchachos Observatory).
Fly there in 3DGJ 3998 b goes round its star every 2.65 days, 33 times as often as Mercury goes round the Sun.
| Spectral type | M1 |
| Surface temperature | 3,726 K |
| Mass | 0.52 solar masses |
| Radius | 0.5 solar radii |
| Luminosity | 0.04385 times the Sun |
| Apparent magnitude | 10.844 |
| Age | about 8.38 billion years |
| Distance from the Sun | 59.2 light-years (18.1 parsecs) |
| Position (J2000) | RA 259.0021°, Dec 11.0562° |
| Constellation | Ophiuchus |
| Planet | Year | Orbit | Radius | Mass | Found |
|---|---|---|---|---|---|
| GJ 3998 b | 2.65 days | 0.0300 AU | 1.39 R⊕ estimated | 2.5 M⊕ minimum | Radial Velocity, 2016 |
| GJ 3998 c | 13.7 days | 0.0900 AU | 2.5 R⊕ estimated | 6.82 M⊕ minimum | Radial Velocity, 2016 |
| GJ 3998 d | 41.8 days | 0.189 AU | 2.34 R⊕ estimated | 6.07 M⊕ minimum | Radial Velocity, 2025 |
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.