Today, astronomers have numerous extrasolar systems to study, but most look very different from our own. Determining how these solar systems — and ours — formed is challenging. New research presented at the 233rd Meeting of the American Astronomical Society in Seattle, Washington, on January 8 lends credence to an idea that goes against previous thoughts about planet formation, but has been gaining traction in the field: Giant planets that orbit their stars in a matter of days may have formed in place close to their suns, rather than moving inward from much farther away.
The work, published October 5 in The Astrophysical Journal Letters by Elizabeth Bailey and Konstantin Batygin of Caltech, shows that such giant planets — called hot Jupiters — can form in situ, or in place close to their stars, and remain there over their lifetimes without evaporating away. Hot Jupiters are giant planets that orbit very close to their host star, typically less than one-tenth the distance between Earth and the Sun. They are found in about 1 percent of systems. Since their initial discovery in the 1990s, astronomers have wondered how these strange planets got to where they are today. “In the solar system, there’s really nothing orbiting interior to Mercury — not even a belt of asteroids. So for there to be giant planets not only well within the snow lines of their stars, but also well within the orbital distance of Mercury, presented a major challenge to the existing understanding of planet formation,” Bailey said in a press conference.
