A group of Astronomers searching for brown stars across the galaxy recently revealed that the Milky Way could be accommodating 25 to 100 billion brown dwarf stars, and maybe even more.
As part of their research, the group first surveyed five star clusters closer to our solar system before turning their attention to a more distant but young star cluster called RCW 38. RCW 38, which is located at a distance of 1.7 kiloparsecs or 5,544.66 light years away, provided the surprising discovery that brown dwarves are more common than originally believed.
While star clusters close to our solar system usually had one brown dwarf in every seven stars, the RCW 38 cluster shows evidence of five brown dwarves in every 10 stars, or a ratio of 1:2.
"We've found a lot of brown dwarfs in these clusters ... Brown dwarfs form alongside stars in clusters, so our work suggests there are a huge number of brown dwarfs out there," Dr. Aleks Scholz explains. Dr. Scholz is a team member from the University of St. Andrews.
The findings were presented on July 6 at the National Astronomy Meeting held in the United Kingdom. A preprint of the study [PDF] is available online.
Finding Brown Dwarves
The collaborating astronomers used the European Southern Observatory's Very Large Telescope (VLT) located in Northern Chile to observe star cluster RCW 38. The adaptive-optics camera NACO was also used to obtain sharp images like the one below.
The findings from the RCW 38 observation support other surveillances in closer but less dense star clusters, leading the astronomers to believe that 100 billion brown dwarves could still be an underestimation.
"It seems that brown dwarfs form in abundance in a variety of star clusters ... They are ubiquitous denizens of our Milky Way galaxy," collaborator Ray Jayawardhana from York University expressed.
The discovery also leads astronomers to suggest that the condition of the environment has little to do with how brown dwarves form.
"The fact that they have found just as many brown dwarfs in RCW 38 suggests that the environment where the stars form, whether stars are more or less massive, tightly packed or less crowded, has only a small effect on how brown dwarfs form," Jayawardhana concludes.
What Are Brown Dwarves?
Brown dwarves are considered by the astronomers as failed stars because they do not have the same capacity to sustain power like our sun does.
A brown dwarf is usually bigger than a planet but smaller than the "legit" stars we know of, with mass ranging from about 90 times that of Jupiter to about 10 percent of our sun.
However, brown dwarves were unable to spark a fusion reaction that could have turned them into a bright star. That said, these dwarves usually show up faint even when our powerful telescopes pick them up, making them hard to spot and identify — like a flashlight that is almost out of battery or charge. Just take a look at the photo below to compare its brightness with a successful star.
