Planet around Sun-like star
Astronomers have snapped what may turn out to be the first picture of a planet orbiting a star similar to the Sun. If confirmed, it could challenge estimates of how far away planets can form from their host stars.
The planet weighs 8 times as much as Jupiter and appears close to a young star that weighs slightly less than the Sun. Both objects are roughly 500 light years away from Earth.
More than 300 extrasolar planets have been found orbiting distant stars. Most have been discovered by looking for stellar wobbles that suggest gravitational tugs by a close-in companion.
But taking a snapshot of these planets has proved difficult because they tend to be close to their stars, and the stars far outshine them.
To search for planets farther out, Ray Jayawardhana of the University of Toronto and colleagues decided to look at young stars. That’s because gas giant planets like Jupiter retain the heat from their formation – and are therefore brighter – in their youth than they are later in life.
In a survey of more than 85 stars using the Gemini North telescope in Hawaii, the team found one potential planet that is 8 times as massive, 10 times as hot and roughly 30,000 times as bright as Jupiter near a star called 1RXS J160929.1-210524. The star is 85% as massive as the Sun but less than 0.1% its age, at an estimated 5 million years old.
The planet appears to orbit the star at a distance of 330 astronomical units (1 AU is the distance from the Earth to the Sun). By comparison, Neptune, the most distant planet in our solar system, orbits the Sun at roughly 30 AU.
That distance is so large that it contradicts models of planetary formation, which suggest that planets coalesce from a disc of gas and dust left over from the Sun’s birth. Such discs are thought to contain too little material at such distances to form planets.
Rachel Courtland
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