K2-33b: a hot Neptune only 10 Million Years old

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 the June 20 advance 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."

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