A University of Florida astronomy professor discovered an unusual star system that challenges the current scientific theory on how solar systems form.
Jian Ge, Ph.D., spent the last eight years, along with his postdoctoral researcher Bo Ma, confirming research on the first “binary-binary” system.
This star system is rare, Ge said, because its data contradicts the popularly accepted idea of how solar systems were created.
In a traditional binary system, two objects in space are so close together that both gravities cause the objects to orbit around each other. HD 87646, like a regular binary system, has two stars which orbit the other. The stars are 22 astronomical units apart, which is about the distance between the Sun and Uranus.
However, HD 87646 is abnormal and referred to as “binary-binary” because the primary star has an additional two celestial bodies moving in a separate orbit around it.
The first celestial body, named MARVELS-7a, is a giant planet and is 12 times the mass of Jupiter, while the second body, MARVELS-7b, is a brown dwarf – or “failed star” – and is 57 times the mass of Jupiter.
Ge led a team in creating the device used to observe this star system at the Apache Point Observatory in New Mexico. The W. M. Keck Exoplanet Tracker – a Doppler device known as KeckET – is remarkable because it allows astronomers to observe dozens of objects in space at the same time. HD 87464’s data was obtained from KeckET, as well as from over 30 astronomers around the world.
Ma’s simplified explanation of the discovery refers back to Earth.
“You know our solar system, right?” Ma said. “You know we have a sun here; we have a lot of planets basically in the same plane, in a disk.”
Now, Ma said, imagine there’s another star that’s even more massive than the Sun in the position of Uranus. With the two stars and planets in these locations, he said, it’s hard to use the current theory to explain how Jupiter, Earth and the rest of the solar system could have formed and remained stable.
Thus, Ma explained, this newly discovered system requires a different theory to be fully understood.
The currently accepted solar system formation theory states that everything began as a gigantic cloud of dust and gas. At some point 4.6 billion years, according to NASA’s website, part of that cloud collapsed on itself and created a spinning disk of dust and gas. Once enough material gathered in the center of the disk, the Sun was created. Over time, the remaining 0.2 percent of material not made into the Sun was formed into bigger and bigger pieces, eventually creating the planets, moons, asteroids and comets.
For a more in-depth explanation on the current solar system formation theory, click here.
The primary reason why HD 87646 goes against this theory is because its stars and orbiting celestial bodies are so close together and yet it remains a stable system.
Ge said, years ago, Newton’s Law was accepted to explain the planets and their orbits around the Sun. But later, some planets (like Mercury) were found to not be explained by Newton’s Law. So, Ge said, the accepted solar system theory isn’t necessarily debunked because of the discovery, but is incomplete.
“The discovery of this [system] shows that the planet system – the solar system formation – requires maybe a different approach to understanding how they form,” Ge said. “We are not in the final stage of understanding how [a planet system similar to our solar system] forms in the universe.”
By comparing how long it took to analyze the first set of data to how much data is still left to be studied, Ma said HD 87646 will likely be a life-long research project for him.
“A binary has a really long orbital period, at least 100 years,” Ma said. “So basically for my whole life, I’ll be paying attention to this system.”
Ge said they’ve only hit the tip of the iceberg with what’s possible to discover in this binary-binary system.
“Science [and] astronomy always come with a lot of surprises,” Ge said. “It’s hard to predict what kind of theory you’ll come up with, but we know these discoveries provide [a push] to really demand a new theory or new model to explain.”
Ge and Ma's findings are published in the Astronomical Journal’s November issue.