The 55 Cnc System

5 planets 2 stars 1 in habitable zone Cancer

55 Cnc is a planetary system in the constellation Cancer hosting 5 confirmed exoplanets around 2 stars, about 41 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 55 Cnc

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Planets without a measured radius are not shown.

Star 55 Cnc and Its Habitable Zone

55 Cnc

Spectral type: G8 V
Surface temperature: 5,198 K (Sun: 5,772 K)
Mass: 1.01 M☉
Radius: 0.98 R☉
Age: 10.0 billion years (Sun: 4.6)

55 Cnc b 55 Cnc c 55 Cnc d → 55 Cnc e 55 Cnc f

Too hot Optimistic habitable zone Conservative habitable zone Too cold

Habitable zone of 55 Cnc: 0.615–1.476 AU (conservative: 0.779–1.399 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.

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All 5 Planets in the 55 Cnc System

Planet	Type	Orbit	Radius	ESI	Discovered
55 Cnc b	Cold Gas Giant	15 d	—	0.09	1996
55 Cnc c	Cold Gas Giant	44 d	—	0.19	2004
55 Cnc d	Cold Gas Giant	4,799 d	—	0.09	2002
55 Cnc e	Super Earth	0.7 d	1.88 R⊕	0.26	2004
55 Cnc f HZ	Neptune-like	261 d	—	0.46	2007

Discovery History

The first planet found here, 55 Cnc b, was discovered in 1996 using the radial velocity method. The most recent addition, 55 Cnc f, followed in 2007.

1996 — 55 Cnc b (Radial Velocity)
2002 — 55 Cnc d (Radial Velocity)
2004 — 55 Cnc c (Radial Velocity)
2004 — 55 Cnc e (Radial Velocity)
2007 — 55 Cnc f (Radial Velocity)

Frequently Asked Questions About 55 Cnc

How many planets does 55 Cnc have?

55 Cnc has 5 confirmed exoplanets distributed around its 2 stars. More may await discovery.

Are any planets in the 55 Cnc 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 55 Cnc?

55 Cnc is about 41 light-years from Earth in the constellation Cancer.

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