PTFO8-8695b: the 2 Million Year Old hot Jupiter That is Already Dying

Astronomers searching for the galaxy's youngest planets have found compelling evidence for one unlike any other, a newborn "hot Jupiter" whose outer layers are being torn away by the star it orbits every 11 hours.

"A handful of known planets are in similarly small orbits, but because this star is only 2 million years old this is one of the most extreme examples," said Rice University astronomer Christopher Johns-Krull, lead author of a new study that makes a case for a tightly orbiting gas giant around the star PTFO8-8695 in the constellation Orion. The peer-reviewed study will be published in The Astrophysical Journal and was made available online this week.

"We don't yet have absolute proof this is a planet because we don't yet have a firm measure of the planet's mass, but our observations go a long way toward verifying this really is a planet," Johns-Krull said. "We compared our evidence against every other scenario we could imagine, and the weight of the evidence suggests this is one of the youngest planets yet observed."

Dubbed "PTFO8-8695 b," the suspected planet orbits a star about 1,100 light years from Earth and is at most twice the mass of Jupiter. The team that compiled the evidence was co-led by Johns-Krull and Lowell Observatory astronomer Lisa Prato and included 10 co-authors from Rice, Lowell, the University of Texas at Austin, NASA, the California Institute of Technology and Spain's National Institute of Aerospace.

"We don't know the ultimate fate of this planet," Johns-Krull said. "It likely formed farther away from the star and has migrated in to a point where it's being destroyed. We know there are close-orbiting planets around middle-aged stars that are presumably in stable orbits. What we don't know is how quickly this young planet is going to lose its mass and whether it will lose too much to survive."

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