Scientists Found a Unique Exoplanet in an Evolved Binary

Astronomers used the Kepler Space Telescope to find an exoplanet (having a mass of about 13 Jupiters) that is orbiting a more evolved binary system, called KIC 10544976.  

The Kepler Space Telescope of NASA made it possible for humanity to observe the exoplanets around young binary systems. This outstanding achievement was accomplished, for the first time, in 2011. Since then, astronomers have found many exoplanets that are orbiting two live stars. Having said that, a recent study suggests that the researchers have found evidence of the existence of an exoplanet around an older, more evolved binary system in which one of the stars is dead. The name assigned to this binary system is KIC 10544976 and it is located in the Cygnus constellation. The first author of the paper, Leonardo Andrade de Almeida, announced their successful venture in the following words:

“We succeeded in obtaining pretty solid evidence of the existence of a giant exoplanet with a mass almost 13 times that of Jupiter [the largest planet in the Solar System] in an evolved binary system. This is the first confirmation of an exoplanet in a system of this kind.”  

Clues from the Evolved Binary

Researchers used a couple of clues from the binary system for their research. The first one of them was the Orbital Period of the evolved binary. Almeida explained that variations in the orbital period of a binary are due to gravitational attraction among the three objects, which orbit around a common center of mass. Having said that, he clarified that orbital period variations are not good enough evidence, on a standalone basis, to prove the existence of a planet around a binary star system. The reason for this is the periodic fluctuation of the magnetic field of the binary stars. He elaborated that by saying,

“Variations in the Sun’s magnetic activity eventually cause a change in its magnetic field. The same is true of all isolated stars. In binaries, these variations also cause a change in orbital period due to what we call the Applegate mechanism.”

In order to strengthen their study, the researching team decided to observe another factor, called the Eclipse Timing Variation. In addition to that, they monitored the magnetic activity cycle of the live star to determine more accurate results. Consequently, both the stars of the system (a dead white dwarf and a live red dwarf) were observed rigorously (minute by minute data) by the Kepler Space Telescope between 2009 and 2013. Similarly, a number of ground-based telescopes observed the evolved binary from 2005 to 2017. Talking about the uniqueness of this system, Almeida said,

“The system is unique. No similar system has enough data to let us calculate orbital period variation and magnetic cycle activity for the live star.”

Kepler’s Observations

The researchers used the data from the Kepler to estimate the magnetic cycle of the red dwarf on the basis of the rate and energy of the flares and the variability due to regions of cooler surface temperatures. The in-depth analysis of the data revealed that the orbital period of the evolved binary is around 17 years while the magnetic activity cycle lasts for 600 days (consistent with the magnetic cycles estimated for low-mass isolated stars). Almeida concluded that this finding completely refutes the hypothesis that orbital period variation is due to magnetic activity. The most plausible explanation is the presence of a giant planet orbiting the binary, with a mass approximately 13 times that of Jupiter.

Different Formation Hypotheses

The exact formation mechanism of this exoplanet is unknown to scientists which leads us to some amazing theories. One of them suggests that the planet was formed during the death of the white dwarf from the ejected gas, making it a second-generation body. On the other hand, some astronomers claim that it was developed at the same time as the stars (first generation planet). All we can do is speculate until the point when we could get confirmation about its formation through scientific evidence. Researchers believe that the new, advanced generation of ground-based telescopes, like GMT, might help us solve this riddle but it is expected to see its first light in 2024.