A group of astrophysicists recently released a surprising study. It found that a brown dwarf nicknamed “The Accident” might be double the age of other known brown dwarfs, which suggests there may be more ancient brown dwarfs lurking throughout our galaxy.
The National Aeronautics and Space Administration (NASA) has released footage of the brown dwarf, which was first discovered by citizen scientist Dan Caselden. Caselden had been using an online program he built to locate objects in the data gathered by a telescope.
Astrophysicists have dated “The Accident” back to the early days of the Milky Way, when our galaxy had a different chemical composition. That points to the possibility that brown dwarfs have been part of our galaxy since its inception, and there could be a hidden population of ancient brown dwarfs in outer space, per the Daily Mail.
What Are Brown Dwarfs?
Brown dwarfs are neither full-fledged stars nor fully-formed planets. They’re somewhere in between the two in terms of mass. They develop like stars, but they lack adequate mass to spark nuclear fusion, which is the process that makes stars shine.
Brown dwarfs cool down as they age. And as they do, their intensity in different wavelengths of light shifts. It’s not unlike the way heated metals change color as they cool.
So scientists thought they had brown dwarfs all figured out. That is, until they came across “The Accident.”
Astrophysicists Studied Surprising Brown Dwarf
Astrophysicists studied “The Accident” and reached some startling conclusions about brown dwarfs. They found that the brown dwarf might be 10 to 13 billion years old, at least double the median age of other known brown dwarfs.
“This object defied all our expectations,” said Davy Kirkpatrick, a Caltech astrophysicist and the lead author of the study, which was published in the American Astronomical Society’s Astrophysical Journal Letters.
The brown dwarf’s age would mean that our galaxy may contain many more of these ancient brown dwarfs, which were around soon after the Milky Way formed.
‘The Accident’ Confused Scientists at First
The brown dwarf had some contradictory properties. It was faint in some wavelengths – implying that it’s cold, and old – but bright in other ones, suggesting a higher temperature. So the astrophysicists observed it using a ground-based telescope at the Keck Observatory and confirmed that it was indeed cold.
But was it dim because it’s far away? In fact, no. Using NASA’s Hubble and Spitzer space telescopes, scientists were able to measure the brown dwarf’s distance from Earth. It’s about 50 light-years away.
What’s more, it’s moving fast. “The Accident” is moving faster than all other known brown dwarfs, at about half a million miles per hour. The astrophysicists figure it’s been whizzing around the galaxy for many years, passing massive objects that cause it to accelerate with their gravity.
Brown Dwarf’s Light Profile Suggests It’s Very Old
Ultimately, the astrophysicists determined that the light profile of “The Accident” suggests it has very little methane, unlike other observed brown dwarfs. And that in turn suggests it formed when our galaxy was still carbon-poor. (Very little carbon when it formed equals very little methane in its atmosphere now.)
“It’s not a surprise to find a brown dwarf this old, but it is a surprise to find one in our backyard,” said Federico Marocco, a Caltech astrophysicist who led the observations using the Keck and Hubble telescopes. “We expected that brown dwarfs this old exist, but we also expected them to be incredibly rare. The chance of finding one so close to the solar system could be a lucky coincidence, or it tells us that they’re more common than we thought.”
Kirkpatrick said there are very likely more oddities out there like this brown dwarf. The challenge for scientists is just to figure out how to look for them.