Researchers now have evidence that rocky planets may be present in a Tatooine-like system with a double sun located about 1,000 light-years away.
In a study funded by the European Research Council and the Science and Technology Facilities Council, researchers led by a team from the University College London reported the discovery of shattered asteroid remains moving around a double sun system known as SDSS 1557. As the debris appears to be made of rock, it suggests that planets of the same nature might be in existence in the system.
So far, all exoplanets that have been discovered orbiting double sun systems were gas giants much like Jupiter, and were believed to have formed in their systems's icy regions. Unlike icy material rich in carbon found within other double sun systems, those identified in SDSS 1557 were highly metallic and included magnesium and silicon. The researchers were able to identify the elements when debris flowed onto one of the suns' surfaces, temporarily polluting it with matter the size of a minimum of 1.1 trillion U.S. tons. That's an area about as big as an asteroid that is at least 2.5 miles in size!
According to Jay Farihi, the study's lead author, it's challenging for rocky planets to form in double sun systems because gravitational forces from the two (one white dwarf and one brown dwarf in the case of SDSS 1557) would result in constant and tremendously strong pushing and pulling that will prevent dust and rocks from sticking together.
"With the discovery of asteroid debris in the SDSS 1557 system, we see clear signatures of rocky planet assembly via large asteroids that formed," he said.
The Connection Between Asteroids And Planets
The solar system's asteroid belt features leftover building blocks from terrestrial planets such as Mars, Earth, Venus, and Mercury. To understand then how rocky, possibly habitable planets came to be, researchers turn to asteroids.
This is the same approach used by Farihi and colleagues as no planet has been detected directly yet in SDSS 1557, no thanks to the widespread debris in the system.
A Surprise Discovery
Discovering evidence of rocky planets in the system actually came as a surprise to the researchers because they initially thought SDSS 1557 was a single-sun system. Steven Parsons, a study co-author, was the one who noticed that they were actually looking at a double sun system.
He explained that thousands of binary systems similar to SDSS 1557 are already known. However, this was the first time that pollution and debris from asteroids were observed in a system. All that pollution and debris hid the brown dwarf from sight until the right instrument was used to view SDSS 1557.
To study the double sun system and its debris's chemical composition, the researchers used the European Southern Observatory Very Large Telescope and the Gemini Observatory South Telescope to measure differences in light wavelength absorption. When gathered data was analyzed, it yielded results that were compelling and consistent.
To acquire conclusive proof that the dust swirling in SDSS 1557 is indeed rocky in nature and not icy, the researchers will be observing the system next using the Hubble telescope.