astronomy link of the day
Scientists have discovered an ancient, gigantic planet orbiting a white dwarf star. The revelation of the planet, much older than any thought to have existed, may cause scientists to revise their theories of cosmic evolution.
About 800 times more massive than Earth, the planet was born around a yellow, sun-like star about 13 billion years ago. That is about 9 billion years earlier than any planet previously detected and a mere billion years after the big bang that spawned all space and time -- a time, most astronomers believe, when the universe had yet to create the raw material needed to make planets, according to researchers who revealed their findings yesterday.
The discovery could change theories about how easily nature makes planets from even the skimpiest of raw materials, and about the abundance of planets -- including some that might harbor life -- thriving unexpectedly in odd corners of the cosmos, astronomers said.
"What we think we've found is an example of the first generation of planets formed in the universe," said Steinn Sigurdsson of Pennsylvania State University, a member of the observing team. "We think this planet formed with its star 12.713 billion years ago, when the [Milky Way] galaxy was . . . just in the process of forming."
For a decade, the identity of this object had been an astronomical mystery. The observing team solved it by combining the sharp vision of the Hubble Space Telescope with other instruments and techniques, plus many years of inventive detective work. The results were announced at a NASA headquarters news conference yesterday and in today's issue of the journal Science.
Confirmation that the object is a planet "is a stunning revelation," said Alan P. Boss of the Carnegie Institution of Washington, an expert on the formation of planetary systems who is not a member of the observing team. "This means that 13 billion years ago, life could have arisen and then died out," he said. "This has immense implications."
...Less than a decade ago, astronomers were still struggling to confirm the first planet detected beyond the family of the sun. Now, the population of known extrasolar planets exceeds 100. But the latest addition breaks the mold in several ways, Boss said.
Today, the planet orbits an odd couple made up of a cold, collapsed star called a white dwarf and an even more bizarre companion known as a pulsar, which spins on its axis almost 100 times a second. The newfound planet is the only one known to orbit such a double star system.
This eccentric trio resides at the core of the ancient globular star cluster M4, about 5,600 light-years from Earth in the direction of the summer constellation Scorpius. That cluster is visible in binoculars as a fuzzy white smudge very near the bright star Antares.
The planet's habitat is as noteworthy as its longevity, astronomers said. The cluster was the site of a furious firestorm of star birth in its early history, and the young planet must have survived blistering ultraviolet radiation, the shockwaves of stellar cataclysms known as supernovas and other mayhem.