Hubble confirms planets are made from dust

The NASA/ESA Hubble Space Telescope has confirmed that planets are born from disks of dust and gas that revolve around their home stars. The observations by an international team of astronomers led by G Fritz Benedict and Barbara E McArthur of the University of Texas, Austin, US showed for the first time that a planet is aligned with its star's circumstellar disk of debris.

They found that planet detected in 2000, which orbits the nearby Sun like star Epsilon Eridani, located 10.5 light-years from Earth in the constellation Eridanus, is inclined 30 degrees to Earth, the same angle at which the star's disk is tilted, reports DailyIndia.

According to Cosmos, the planets in our Solar System share a common alignment, evidence that they were created at the same time in the Sun's disc. But the Sun is a middle-aged star - 4.5 billion years old - and its debris disc dissipated long ago. Epsilon Eridani, however, still retains its disc because it is young, only 800 million years old.

The planet's orbit is inclined 30 degrees to Earth, the same angle at which the star's disc is tilted.

The planet's true mass, the key to describing the object as a planet, is 1.5 times Jupiter's mass. The planet, called Epsilon Eridani b, is the nearest extrasolar planet to Earth. It orbits its star every 6.9 years.

Although Hubble and other telescopes cannot image the gas giant planet now, they may be able to snap pictures of it in 2007, when its orbit is closest to Epsilon Eridani. The planet may be bright enough in reflected sunlight to be imaged by Hubble, other space-based cameras, and large ground-based telescopes.

"Because of Hubble, we know for sure that it is a planet and not a failed star," Barbara McArthur of the University of Texas explained. She led the research along with her colleague G Fritz Benedict.

Making that deduction was not the work of five minutes. The team first identified the planet using the radial-velocity method. This measures tiny changes in a star's motion towards and away from Earth to infer the existence of unseen companions.

The team studied over a thousand astrometric observations from Hubble combined with other astrometric observations made at the University of Pittsburg's Allegheny Observatory. All this data was added to hundreds of ground-based radial-velocity measurements made over the past 25 years at various telescopes including the European Southern Observatory in Chile, and the McDonald Observatory at the University of Texas, informs The Register.

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