A failed star called puzzle astronomers

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Dan Caselden was until late November 3, 2018, playing a video game Counter-Strike, when he entered the history of astronomy. Every time he died, he would jump on his laptop to check for an automated image search of NASA’s space telescope.

Suddenly, in the early hours of the morning, something bizarre came into view. “It was very confusing,” Caselden said. “It was moving faster than anything I discovered. It was weak and fast, which made him very strange. ”

Caselden emailed the astronomers he worked with as part of it Backyard Worlds: Planet 9 project. After ruling out the possibility that it was a pictorial artifact, they realized they were looking at something completely unusual, an extremely faint object 50 light-years away blazing through a galaxy at a speed of 200 kilometers per second. It was named WISE 1534-1043, but due to its unique characteristics and accidental discovery, it soon earned a nickname. “accident. ”

Astronomers now think Caselden has found a brown dwarf – a failed star that lacks the amount needed to start nuclear fusion in its core. “It shapes like a star,” he said Sarah Casewell, an astronomer from the University of Leicester in the UK. “However, it never gets enough mass to fuse hydrogen into helium and start burning anything.”

The discovery of the accident pointed out that we still have a lot to learn about brown dwarfs. The mass of these objects ranges from an estimated 13 times the mass of Jupiter to 75 or more times, but the constant dilemma is where those two boundaries lie. “People are constantly discussing this at conferences,” he said Beth Biller, an astronomer from the University of Edinburgh in the UK, especially the lower limit. While 13 is the mass of Jupiter is approximately the mass at which deuterium fusion may occur– the characteristic by which brown dwarfs differ from the planets of gaseous giants – the limit may vary. “There’s nothing special about the 13 masses of Jupiter,” Biller said. “It’s completely ad hoc.”

Brown dwarfs also vary greatly in temperature. The warmest have a surface temperature of about 2,000 degrees Celsius – “roughly that of a candle flame,” Biller said. The coldest are below 200 degrees. As they do not have their own heat source, brown dwarfs will gradually cool to these lower temperatures over billions of years. (Dwarfs, which further blur the boundary between planets and brown dwarfs, may be colder. WISE 0855-0714 is below zero. (It’s the coldest object we know outside of our solar system, “Biller said.)

It is also unclear what the brown dwarf might look like up close. Despite their name –suggested by astronomer Jill Tarter 1975 – Probably not brown. They are more orange or red. “For better or worse, it’s left as a name,” he said Davy Kirkpatrick, an astronomer at the California Institute of Technology.

They also have an atmosphere, and those atmospheres can show some kind of banded and stormy storms, like Jupiter. Last year, Biller and her colleagues took advantage of these storms measure the wind speed on the brown dwarf about 34 light-years away. They first watched the elements in its atmosphere come and go out of sight as they rotated, and then compared this speed to measuring the speed of rotation of an object from the interior collected from its magnetic field. Comparing these two values, the researchers calculated wind speeds of over 2,300 kilometers per hour – more than five times the wind speed of Jupiter.

Because brown dwarfs bridge the gap between stars and planets, they can help us understand both. At the upper end of the mass scale, the boundary between the largest brown dwarfs and the smallest stars can give us an insight into how nuclear fusion begins. The object must reach a temperature of about 3 million degrees Celsius at its core to launch nuclear fusion, he said Nolan Grieves University of Geneva, Switzerland; this ignites a chain reaction that converts hydrogen to helium. But no one is sure how much mass it takes for this to happen and at what point the brown dwarf becomes a star. “There are many aspects of stellar evolution about which our knowledge is still quite uncertain,” Biller said. “Where is that fusion boundary is one of those questions.”



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