- BBC News World
They are not quite stars or quite planets, but something in between, and there could be more than previously thought in our galaxy.
This is assured by a new study published by the scientific journal The Astrophysical Journal, which focuses on a new and “enigmatic” brown dwarf who has been nicknamed “The Accident”, because it was discovered by chance.
Brown dwarfs are objects too small to be stars and too big to be considered planets. They are sometimes called “failed stars“.
“This object defied all of our expectations,” said Davy Kirkpatrick, a co-author of the study and an astrophysicist at the California Institute of Technology (Caltech).
The study notes that The Accident could be between 10 billion and 13 billion years old, making it at least twice as old as other brown dwarfs that have been previously discovered.
This suggests that it formed when our galaxy was much younger and had a different chemical composition.
“If that’s the case, there are likely many more of these ancient brown dwarfs lurking in our galactic neighborhood,” adds Kirkpatrick.
A different brown dwarf
The Accident, formally known as WISEA J153429.75-104303.3, was discovered by scientist Dan Caselden by sheer luck, as it does not look much like any other brown dwarf found in the galaxy to date, according to a NASA statement.
As brown dwarfs grow old, cool down, and their brightness changes at different wavelengths, similar to the way hot metals change color when cooled.
The object puzzled scientists because its brightness is not typical of that seen in other aging brown dwarfs.
Radiates a weak light at some key wavelengths, suggesting they are very cool, but at the same time showing brighter elsewhere, indicating those areas are warmer.
“It is not a surprise to find such an old brown dwarf, but it is a surprise to find one in our backyard,” says Federico Marocco, Davy Kirkpatrick’s colleague at Caltech and a co-author of the study.
“We expected brown dwarfs of this age to exist, and we also expected them to be incredibly rare,” continues the astrophysicist, who has been in charge of directing the observations using the Keck and Hubble telescopes.
800.000 km/h faster
Using ground-based telescopes at the WM Keck Observatory in Hawaii, the researchers attempted to observe The Accident with additional infrared radiation.
But the brown dwarf looked so faint that it was undetectable, confirming that it is very cold and therefore very old.
The researchers estimate the speed at which it turns is further proof that has occupied the galaxy for a long time, because it has dragged massive objects that make it accelerate with its gravity.
The Accident is located about 50 light years from Earth and rotates at approximately 800,000 km / h faster than all other brown dwarfs discovered at a similar distance from our planet, according to the study.
Another characteristic of The Accident, the study highlights, is that it contains low levels of methane, compared to most of the other brown dwarfs found, which further strengthens the argument that it was formed more than 10 billion years ago. , when the galaxy was composed almost entirely of hydrogen and helium, and lacked the necessary carbon to create methane.
“The possibility of finding one so close to the Solar System could be a lucky coincidence or it means that they are more common than we think,” concludes Marocco.
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Eddie is an Australian news reporter with over 9 years in the industry and has published on Forbes and tech crunch.