The GJ 357 System

3 planets 1 in habitable zone Hydra

GJ 357 is a planetary system in the constellation Hydra hosting 3 confirmed exoplanets, about 31 light-years from Earth. One of its planets orbits within the habitable zone, where liquid water could exist on a planetary surface.

Size Comparison: The Planets of GJ 357

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Planets without a measured radius are not shown.

GJ 357: Star and Habitable Zone

GJ 357

Spectral type: M2.5 V
Surface temperature: 3,505 K (Sun: 5,772 K)
Mass: 0.34 M☉
Radius: 0.34 R☉

GJ 357 b GJ 357 c GJ 357 d

Too hot Optimistic habitable zone Conservative habitable zone Too cold

Habitable zone of GJ 357: 0.101–0.263 AU (conservative: 0.128–0.249 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.

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All 3 Planets in the GJ 357 System

Planet	Type	Orbit	Radius	ESI	Discovered
GJ 357 b	Terrestrial	3.9 d	1.20 R⊕	0.40	2019
GJ 357 c	Super Earth	9.1 d	—	0.53	2019
GJ 357 d HZ	Super Earth	56 d	—	0.58	2019

Discovery History

The first planet found here, GJ 357 b, was discovered in 2019 using the transit method.

2019 — GJ 357 b (Transit)
2019 — GJ 357 c (Radial Velocity)
2019 — GJ 357 d (Radial Velocity)

Frequently Asked Questions About GJ 357

How many planets does GJ 357 have?

GJ 357 has 3 confirmed exoplanets. More may await discovery.

Are any planets in the GJ 357 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 357?

GJ 357 is about 31 light-years from Earth in the constellation Hydra.

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