The GJ 3998 System

3 planets 1 in habitable zone Ophiuchus

GJ 3998 is a planetary system in the constellation Ophiuchus hosting 3 confirmed exoplanets, about 59 light-years from Earth. One of its planets orbits within the habitable zone, where liquid water could exist on a planetary surface.

GJ 3998: Star and Habitable Zone

GJ 3998

Surface temperature: 3,726 K (Sun: 5,772 K)
Mass: 0.52 M☉
Radius: 0.50 R☉
Luminosity: 0.0439 L☉
Age: 8.4 billion years (Sun: 4.6)

GJ 3998 b GJ 3998 c GJ 3998 d

Too hot Optimistic habitable zone Conservative habitable zone Too cold

Habitable zone of GJ 3998: 0.171–0.438 AU (conservative: 0.216–0.415 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.

See the full interactive habitable-zone view in the Exoplanet Explorer app ›

All 3 Planets in the GJ 3998 System

Planet	Type	Orbit	Radius	ESI	Discovered
GJ 3998 b	Super Earth	2.7 d	—	0.31	2016
GJ 3998 c	Super Earth	14 d	—	0.44	2016
GJ 3998 d HZ	Super Earth	42 d	—	—	2025

Discovery History

The first planet found here, GJ 3998 b, was discovered in 2016 using the radial velocity method. The most recent addition, GJ 3998 d, followed in 2025.

2016 — GJ 3998 b (Radial Velocity)
2016 — GJ 3998 c (Radial Velocity)
2025 — GJ 3998 d (Radial Velocity)

Frequently Asked Questions About GJ 3998

How many planets does GJ 3998 have?

GJ 3998 has 3 confirmed exoplanets. More may await discovery.

Are any planets in the GJ 3998 system habitable?

One planet in the system orbits within the habitable zone, where liquid water could exist. Actual habitability depends on atmospheres and composition, which are not yet known.

How far away is GJ 3998?

GJ 3998 is about 59 light-years from Earth in the constellation Ophiuchus.

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