Wednesday, November 5, 2008

55 Cancri AB

55 Cancri AB star system compared to Sol.
Star type
g A: G8 V
g B: M3.5 V

Distance from Earth
g 40.9 ly

Star Service No.
g NA

g A: Chromospheric activity suggests an age of around 5.5 billion years; other studies yield age estimates of 7.4 and 8.7 billion years.
g B: NA

Radius/Mass/Temp (xSol)
g A: 30%; 85%; 5373 ± 9.7 K
g B: NA; 13%; NA

Brightness (xSol)
g A: 63%
g B: 0.076%

g A: More enriched than our sun in elements heavier than helium, with 186% the solar abundance of iron; it is therefore classified as a rare "super metal-rich" (SMR) star
g B: NA

Comparison to Sol
g A: NA
g B: NA

Picture of star
g A: NA
g B: NA

Star system features
g A: A METI message to 55 Cancri was transmitted from Eurasia's largest radar – 70-meter (230-foot) Eupatoria Planetary Radar. The message was named Cosmic Call 2; it was sent on July 6, 2003, and it will arrive at 55 Cancri in May 2044.

Known planets (orbiting 55 Cancri A)
g 55 Cancri b (aka HR 3522b and 55 Cancri Ab): Periodicity of around 14.7 days corresponding to a planet at least 83% of the mass of Jupiter at 0.11 AU from parent star.
g 55 Cancri c: Mass is ≥0.17 of Jupiter at a distance of 0.24 AU, orbiting parent star every 44.36 days.
g 55 Cancri d: Orbiting at a distance of around 5.74 AU. Mass is 3.82 ± 0.04 of Jupiter, orbiting parent star every 5169 ± 53 days.
g 55 Cancri e: Completing one orbit in only 18 hours, the alien planet is 26 times closer to its parent star than Mercury is to the Sun (or 0.016 AU from parent star); the star terrifying fills the daytime sky. If Earth were in the same position, the soil beneath our feet would heat up to about 3200 F. Researchers have long thought that the planet must be a wasteland of parched rock. As the planet has a mass 7.8 times and a radius just over twice that of Earth, however, about a fifth of the planet's mass must be made of light elements and compounds, including water. Given the intense heat and high pressure these materials likely experience, researchers think the compounds likely exist in a "supercritical" fluid state, a high-pressure, high-temperature state of matter best described as a liquid-like gas, and a marvelous solvent. Water and carbon dioxide may be literally oozing or steaming out of the rocks. In 2012, scientists suggested it may be a diamond planet. The surface would be covered in graphite and diamond rather than water and granite. Up to a third of the planet may be composed of diamond with the rest largely of carbon (as graphite), iron, silicon carbide, and, possibly, some silicates with virtually no water at all.
g 55 Cancri f: Half the mass of Saturn in a 260-day orbit, located 0.78 AU from parent star, planet is in 55 Cancri A's habitable zone.

Habitable zones
g A: Terrestrial planets, with substantial amounts of water, could exist in the planet’s habitable zone. 55 Cancri f is located within this zone; the planet itself is not thought to be conducive to life, but hypothetical moons in principle could maintain at least microbial life.
g B: NA

Orbital map
g Stars A and B separated by about 1065 AUs; map of star system; artist's rendition of planets in relation to star
g A: NA
g B: There are indications that component B may itself be a double star, though this is uncertain.

View from stars
g NA

Nearby stars
(Star systems with 10 light years)
g NA

Map locating star system
g NA

Location in Earth sky
g In constellation Cancer; visible with binoculars

Other names
g A: Rho-1 Cancri; 55 Cnc; BD+28°1660, Gliese 324, HD 75732, HIP 43587, HR 3522
g B: NA

Sci-fi mentions
g A: NA
g B: NA

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