First Planet to Orbit a Dwarf Star, NASA Reveals

A star swells up and shrinks back when its fuel depletes, swallowing the objects around it. Turns out it wasn't the case for this newly discovered white dwarf.
Deniz Yildiran

Seems that planets do not necessarily orbit stars way much bigger than their size, as our tiny Earth orbits the giant Sun. 

Recently, NASA's Transiting Exoplanet Survey Satellite and Spitzer Space Telescope, a telescope which is currently taking time off work, have witnessed an unusual orbit and served it in our plates. They have revealed that an intact planet is orbiting a white draft in a close distance for the first time ever recorded. 

The recent paper on the discovery led by Andrew Vanderburg and other NASA co-authors, has been published in Nature on September 17. 


The little sun-like star is only 40% larger than Earth, as NASA reported

It appeared a unique situation as the white dwarf, named WD 1856+534, is the remnant of a previous cooler red giant, which typically engulfs the objects close to it during its metamorphosis. In other words, the objects nearby don't even have a slight chance of floating in the empty space during a red giant's gas ejection.

What is more, losing up to 80% of its mass, the dwarf stars move on with their hot cores, alone. 

“We’ve known for a long time that after white dwarfs are born, distant small objects such as asteroids and comets can scatter inward towards these stars. They’re usually pulled apart by a white dwarf's strong gravity and turn into a debris disk,” explained co-author Siyi Xu, an assistant astronomer at the international Gemini Observatory in Hilo, Hawaii. “That’s why I was so excited when Andrew told me about this system. We’ve seen hints that planets could scatter inward, too, but this appears to be the first time we’ve seen a planet that made the whole journey intact.”

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Vanderburg assumes the WD 1856 b, as the planet was named, used to be at least 150 times farther away from the star compared to its current position. It seems that the little dwarf is a chosen one. 

TESS detected that WD 1856 b is approximately 80 light-years away in the north of the constellation called Draco and turning around WD 1856+534 which is 11,000 miles (18,000 kilometers) overall. One orbit is completed in 34 hours - it is 60 times faster compared to Mercury orbiting the Sun. 

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