Flipping Exoplanets Found in Distant Binary System

A recent investigation of the 55 Cancri binary star system has revealed that five of the planets surrounding the largest star do somersaults in their orbits, over the course of millions of years. One of the gas giants leads the way, forcing the other four to follow suit.

The planet in question, called 55 Cancri d, slowly flips once every few million years, under the influence of its parent star's companion. However, due to its massive weight, it also draws the other four exoplanets along for the ride, forcing them to behave in a similar manner.

The research that arrived at this conclusion was led by investigator Nathan Kaib, who holds an appointment with the Queen's University, in Canada. He is also the lead author of a new study detailing the findings, which appears in the December issue of the Astrophysical Journal Letters.

The 55 Cancri system is located very close by, at a distance of only 40 light-years, in the direction of the constellation Cancer, Space reports. What is interesting to note is that the companion star is located at a distance of around 1,100 astronomical units (AU).

An AU is the equivalent of the mean distance between Earth and the Sun, or 93 million miles (157 million kilometers). Even at this distance, the second star influences the motions of the planets around the first, though the effects are mostly exert on their axes, not their orbits proper.

In general, planets tend to align their axis with those of their parent stars. On occasions, the two differ, as is the case with Earth and the Sun. Our planetary axis is inclined at an angle of more than 23 degree in respect to the Sun's axis, Space reports.

The gas giant 55 Cancri d is one of very few planets known that swing their axis by a wide margin, as evidenced by more than 450 computer simulations conducted at Queen's University. The object's axis most likely flips upside-down, and then back again, over the eons.

What is very interesting to note here is that the phenomenon does not affect the orbit of the planet itself, nor does it force any discernible changes in the orbits of the other four companions. Detecting the axis change has thus far never been hinted at.

“Other studies looking at the effect of binary stars on planets tend to focus on tighter binaries,” Kaib says. Researchers have never analyzed a binary that is spread out by such a wide margin. “This planetary system looks very well ordered,” the team leader explains.

Additional insights on how fast 55 Cancri d flips its axis could be obtained if astronomers are able to determine how fast the two stars spin around each other. However, finding this out is a very complex process, so the data may elude us for a little while longer.