Tuesday, November 11, 2014

Young Star HD 95086: Two dust belts surrounded by a large dust halo

An artist's impression of a young star surrounded by debris rings and a vast dust halo. 

Credit: NASA/JPL-Caltech

Scientists at the University of Arizona have discovered what might be the closest thing to "baby photos" of our solar system.

A young star called HD 95086 is found to have two dust belts, analogous to the asteroid and Kuiper belts in the Solar System, surrounded by a large dust halo that only young planetary systems have.

Similar dust structures are also found around another, slightly older star called HR 8799, where four massive planets occupy the large gap between the two belts.

HR 8799, the first star found to host four directly imaged planets, is often referred to as a younger and scaled-up version of our Solar System.

Finding another star similar to HR 8799 suggests a common model for how stars form planets and how their planetary systems evolve.

The ages of these systems span an interesting period, about 10 to 90 million years, when terrestrial planets form and giant planets settle down to their final configuration in our own Solar System, the team reports.

"We think HD 95086 is a snapshot of what our solar system might have looked like when it was only 10 to 20 million years old," said Kate Y.L.Su, an associate astronomer in the UA's Department of Astronomy and Steward Observatory and lead author of the paper.

Using data from NASA's Spitzer Space Telescope and ESA's Herschel Space Observatory combined with detailed simulations, the researchers found HD 95086 and HR 8799 each have a vast disk halo of fine dust, suggesting enhanced collisional activities in their Kuiper-belt-like belts.

This is an expected behavior for systems that are experiencing dynamical settling of gas giants and possibly late formation of giant ice planets.

A schematic view of the HD 95086 system. Credit: NASA/JPL-Caltech

The large gap between the warm and cold belts in HD 95086, HR 8799 and some other nearby older systems like debris disk twins Vega and Fomalhaut is an excellent signpost for multiple, yet-to-be-discovered planets, according to the research team.

HD 95086 and HR 8799 are located 295 and 129 light years from Earth in the constellations of Carina and Pegasus, respectively.

"The HD 95086 system with its a young star hosting at least one planet of about five Jupiter masses along with massive asteroid and Kuiper-like debris belts is a promising target for planet hunting,"

Su said. "Both systems are very similar, except the HD 95086 has more dust, which is in line with theories of planet formation and leads us to believe it is the younger of the two. By looking at other systems like these we can piece out how our solar system came to be."

"There have to be more planets than have been discovered to make a gap that is this big," said Sarah Morrison, a co-author of the paper and a PhD student in the UA's Department of Planetary Sciences who ran computer models to constrain the possibilities of how many planets are likely to inhabit the system, what their masses could be like and where their orbits could be.

"We think that the system is a prime candidate for direct imaging campaigns to find those planets."

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