Planet formation is a complex and tumultuous process that remains shrouded in mystery. Astronomers have discovered more than 3,000 exoplanets planets orbiting stars other than our Sun however, nearly all are middle-aged, with ages of a billion years or more.

    For astronomers, attempting to understand the life cycles of planetary systems using existing examples is like trying to learn how people grow from babies to children to teenagers, by only studying adults. Now, a team of Caltech-led researchers have discovered the youngest fully-formed exoplanet ever detected. The planet, K2-33b, at 5 to 10 million years old, is still in its infancy.

    The first signals of the planet's existence were measured by NASA's Kepler space telescope during its K2 mission. The telescope detected a periodic dimming in the light emitted by the planet's host star called K2-33 that hinted at the existence of an orbiting planet. Observations from the W.M. Keck Observatory in Hawaii validated that the dimming was indeed caused by a planet, later named K2-33b. A paper detailing the finding appears in online issue of the journal Nature.

    At 4.5 billion years old, the Earth is a middle-aged planet about 45 in human-years," says Trevor David, the first author on the paper and a graduate student working with professor of astronomy Lynne Hillenbrand. "By comparison, the planet K2-33b would be an infant of only a few weeks old." "This discovery is a remarkable milestone in exoplanet science," says Erik Petigura, a postdoctoral scholar in planetary science and a coauthor on the paper. "The newborn planet K2-33b will help us understand how planets form, which is important for understanding the processes that led to the formation of the earth and eventually the origin of life." When stars form, they are encircled by dense regions of gas and dust, called protoplanetary disks, from which planets form. By the time a young star is a few million years old, this disk has largely dissipated and planet formation is mostly complete.

    The star orbited by K2-33b has a small amount of disk material left, indicated by observations from NASA's Spitzer space telescope, demonstrating that it is in the final stages of dissipating. K2-33b was previously identified as a planet candidate in a survey of stars done with the K2 mission, the extended mission phase of the Kepler Space Telescope.

Source: QNA