Astronomers have finally unravelled a decades-long mystery surrounding the renowned brown dwarf, Gliese 229B, making a groundbreaking announcement on Wednesday. The discovery of Gliese 229B in 1995 by Caltech researchers marked the identification of the first known brown dwarf, often referred to as a “failed star.” These celestial objects fall between the size of a planet like Jupiter and a small star and are characterised by their dim nature.
Situated approximately 18 light-years away from Earth, Gliese 229B orbits the red dwarf star Gliese 229. Since this initial discovery, scientists have identified over two thousand brown dwarfs, with estimations in 2017 suggesting there could be around 100 billion scattered throughout the Milky Way galaxy. However, Gliese 229B posed a perplexing puzzle due to its dimness in relation to its size, tipping the scales at about 70 times the mass of Jupiter without emitting significant brightness.
The new revelation from astronomers indicates that the mystery lies in the fact that Gliese 229B is actually a binary system consisting of two brown dwarfs. Weighing around 38 and 34 times the mass of Jupiter respectively, these celestial bodies orbit each other every 12 days. This orbital dance results in a combined brightness that matches the expected output for two brown dwarfs of such size, according to researchers.
Rebecca Oppenheimer, a member of the original Caltech team that made the discovery, expressed excitement over the findings, describing it as the most captivating discovery in substellar astrophysics in decades. The recent research, co-authored by Oppenheimer and published in the journal Nature, was conducted utilising instruments from the European Southern Observatory’s Very Large Telescope in Chile.
The observations taken over five months revealed that the twin brown dwarfs, now named Gliese 229Ba and Gliese 229Bb, orbit a smaller and redder star than our sun every 250 years. Although brown dwarfs emit minimal visible light, they shine more brightly in infrared light, detectable with devices like night-vision goggles or infrared cameras.
Despite this breakthrough, the origins of these paired brown dwarfs remain a subject of speculation among scientists. One theory posits that such duos could develop within the material surrounding a forming star. The discovery raises new questions about the existence of similar binary systems waiting to be unearthed, prompting the research team to consider further exploration using other observatories.
Dimitri Mawet, a senior research scientist at NASA’s Jet Propulsion Laboratory and affiliated with Caltech, highlighted the significance of the discovery, stating that understanding Gliese 229B as a binary system resolves previous discrepancies between its mass and luminosity. Moreover, it deepens the scientific community’s comprehension of brown dwarfs, marking a substantial advancement in astrophysical studies.
In conclusion, the recent unveiling of the binary nature of Gliese 229B has not only shed light on a long-standing mystery but has also opened up new avenues of research and exploration in the realm of astrophysics.