Unusual brown dwarfs discovered in the Milky Way Galaxy
Brown dwarfs are larger than planets and smaller than stars (Gaia/X telescope)
Brown dwarfs of an unusual type were discovered in the Milky Way Galaxy, and they are celestial bodies about which not much data is yet available, thanks to a “technological achievement” of the Gaia and Gravity ground-based space telescopes in Chile. This new type of brown dwarf has characteristics that place it in an intermediate position between planets and stars, according to a study.
Brown dwarfs are larger than planets but smaller than stars, and are difficult to detect because of their weak glow. The ability to see them even decreases when they are near a star a thousand times brighter.
One of the authors of the study published this week in the journal Astronomy and Astrophysics, a researcher at the French National Center for Scientific Research, Sylvester Lacour, explained that monitoring a large number of these brown dwarfs was possible “because they were wandering around alone, like isolated bodies, which prevented being dazzled by the star.”
But brown dwarfs were observed for the first time orbiting near their host stars, at distances equivalent to those that separate the Earth from the Sun. The astronomers relied on the latest list of what was observed by the European space probe Gaia, which maps the stars in the Milky Way galaxy showing their locations. The astrophysicist said that some of these stars showed “a very different orbital motion that leads to the belief that a brown dwarf may be orbiting them.”
From thousands of star systems, eight were chosen to be subjected to the study. Based on these indicators, the Gravity instrument at the European Southern Observatory's Very Large Telescope in Chile focused on the "expected location," explained researcher at the University of Grenoble Alpes, Karen Babuzio, who also participated in the study.
Being a magnifying lens, the interferometer accurately measured objects previously observed by Gaia, enabling scientists to analyze their luminosity and mass, and conclude the presence of brown dwarfs in five of the eight star systems. It turns out that these brown dwarfs, which are considered the "hidden companions" of stars and are located less than 200 light-years from Earth, have a mass between 60 and 80 times the mass of Jupiter.
This discovery will allow a better idea of what brown dwarfs are, which are celestial bodies that can be compared to “aborted stars.” Scientists are particularly interested in knowing whether these objects are “born like stars, by a compressed gas cloud, or like planets, on the edges of an accretion disk around a star,” according to Sylvester Laqueur.
Unlike a star, a brown dwarf does not burn hydrogen in its core, so it is much less luminous (a thousand times less bright in the case of this study), but it still emits a luminous flux that planets do not have. Researchers hope that the next step will be to discover exoplanets thanks to the combined capabilities of the Gaia and Gravity telescopes that allow direct observation of them.
Source: websites