55 Cancri

The 5th Creative Hierarchy is on the verge of liberation. It is active on the intellectual plane.

This graphic depiction compares our solar system with a newfound planetary system, 55 Cancri. The new system has a Jupiter-mass planet in an orbit similar to the orbit of our Jupiter. In addition, two other planets are shown orbiting 55 Cancri at distances closer than the distance between Earth and our Sun.

The planet orbits 55 Cancri in only 14.6 days (16 percent that of Mercury's orbital period around the Sun), has at least 0.84 times the mass of Jupiter, and is 0.11 astronomical units from the star. That is only 16.5 million kilometers, 10.2 million miles, or 28 percent Mercury's distance from the Sun.

Location Constellation: Cancer Right Ascension: 08 52 37.60 Declination: +28 20 02.6 Distance from Sol: 43.7 Light Years Basic Data Alternate Designations: HD 75732 rho1 Cnc HD 75732 HR 3522 Spectral Type: G8 V Apparent Magnitude: 5.95 B-V Color: 0.87 Mass: 1.03 Solar Masses Radius: 0.91 Solar Radii Effective Temperature: 5570 Kelvin Age: 5000 Million Years Habitability Inner Edge of Habitability Zone: 0.42 AU Outer Edge of Habitability Zone: 1.32 AU

The star, 55 Cancri in the constellation Cancer, was already known to have one planet, announced by Butler and Marcy in 1996. That planet is a gas giant slightly smaller than the mass of Jupiter and whips around the star in 14.6 days at a distance only one-tenth that from Earth to the Sun.Using as a yardstick the 93-million mile Earth-Sun distance, called an astronomical unit or AU, the newfound planet orbits at 5.5 AU, comparable to Jupiter's distance from our Sun of 5.2 AU (about 824 million kilometers or 512 million miles). Its slightly elongated orbit takes it around the star in about 13 years, comparable to Jupiter's orbital period of 11.86 years. It is 3.5 to 5 times the mass of Jupiter.

"We haven't yet found an exact solar system analog, which would have a circular orbit and a mass closer to that of Jupiter. But this shows we are getting close, we are at the point of finding planets at distances greater than 4 AU from the host star," said Butler. "I think we will be finding more of them among the 1,200 stars we are now monitoring."

The team shared its data with Dr. Greg Laughlin, assistant professor of astronomy and astrophysics at the University of California, Santa Cruz. His dynamical calculations show that an Earth-sized planet could survive in a stable orbit between the two gas giants. For the foreseeable future, existence of any such planet around 55 Cancri will remain speculative.

"The existence of analogs to our solar system adds urgency to missions capable of detecting Earth-sized planets - first the Space Interferometry Mission and then the Terrestrial Planet Finder," said Dr. Charles Beichman, NASA's Origins Program chief scientist at the agency's Jet Propulsion Laboratory, Pasadena, Calif.

"This planetary system will be the best candidate for direct pictures when the Terrestrial Planet Finder is launched later this decade," said UC Berkeley astronomer Dr. Debra A. Fischer.

Marcy, Butler, Fischer and their team also announced a total of 13 new planets today, including the smallest ever detected: a planet circling the star HD49674 in the constellation Auriga at a distance of .05 AU, one-twentieth the distance from Earth to the Sun. Its mass is about 15 percent that of Jupiter and 40 times that of Earth. This brings the number of known planets outside our solar system to more than 90.

Discovery of a second planet orbiting 55 Cancri culminates 15 years of observations with the 3-meter (118-inch) telescope at Lick Observatory, owned and operated by the University of California. The team also includes Dr. Steve Vogt, University of California, Santa Cruz; Dr. Greg Henry, Tennessee State University, Nashville; and Dr. Dimitri Pourbaix, the Institut d'Astronomie et d'Astrophysique, Universite Libre de Bruxelles.

The star 55 Cancri is 41 light years from Earth and is about 5-billion years old. Further data are needed to determine whether yet another planet is orbiting it, because the two known planets do not explain all the observed Doppler wobbling. One possible explanation is a Saturn-mass planet orbiting about .24 AU from the star.

55 Cancri E

55 Cancri E Statistics

55 Cancri e's close distance to its star raises issues with current models of planet migration via energy loss to protoplanetary disk material during formation. It's small mass would not have been enough to open a gap in the disk and begin migration. So why did it fall into such a tight orbit aroud it's star?

Two theories have been proposed to explain this. The first possibility is that 55 Cancri e was caught up in the overall migration of disk material associated with 55 Cancri b. The most massive of the three inner planets, Planet b was likely the first to open a gap in 55 Cancri's protoplanetary disk and begin migrating in towards the star. If this happened before Planet e could reach the mass required for rapid growth into a gas giant, it could have been carried along by Planet b's migration, placing it in a star hugging orbit before it had the chance to grow much past the rocky core phase.

55 Cancri B

55 Cancri B Statistics

Note: These speculations are out of date. Current theory suggests that the planets of PSR 1257 +12 were probably not survivors of the supernova that created the pulsar. Instead, the supernova may have caused the pulsar to recoil through a close companion, destroying it. Matter from the companion formed an accretion disk around the pulsar, and planets formed from this disk.

55 Cancri C

55 Cancri C Statistics

55 Cancri D

55 Cancri D

Planetary Orbits In the Cancri System