The line separating stars from brown dwarfs may soon be clarified by new astrophysical research.
Serge Dietrich of the Carnegie Institution, along with his team, conducted a study published in the Astrophysical Journal. In their work, scientists have demonstrated that brown dwarfs can be more massive than anticipated.
For a bright glow, stars need energy obtained in the process of thermonuclear reactions in their bowels. If there is too little hydrogen, then the reaction is impossible, and then the object cools, darkens and turns into something known as a brown dwarf. Astronomers around the world are trying to determine the mass, temperature, and brightness of objects on either side of the line drawn between "losers" and ordinary stars.
“Determining the boundary separating stars from brown dwarfs will help to learn more about how they form and develop, as well as clarify whether habitable planets can revolve around them (brown dwarfs. - Author's note),” explains Dietrich …
Projection of the photocenter of the baryocentric orbit Epsilon Indian b and Epsilon Indian c / © Carnegie Institute
Recent theoretical models predict that the boundary between stars and brown dwarfs ranges from 70 to 73 Jupiter masses, or about 7% of the Sun's mass. However, the results obtained by Dietrich's team cast doubt on these calculations.
Scientists have observed two brown dwarfs - Indian epsilon b and Indian c epsilon. They belong to a system that also includes an average luminosity star - Epsilon Indian a. The two brown dwarfs are too faint to be stars, but their masses are 75 and 70 Jupiter masses, respectively.
The team ran the calculations using data from two long-term projects - the Carnegie Astrometric Planet Search at the Las Campanas Observatory and the Cerro Tololo Inter-American Observatory Parallax Investigation led by the Consortium for the Study of Nearby Stars. This made it possible to determine the minute movements of two brown dwarfs against the background of more distant stars.
To the surprise of scientists, the results identified Indian b and Indian c epsilon as stars (by the old definition), even though they are not stars according to observations.
“Taken together, our results mean that current models need to be revisited,” says Dietrich. “We have shown that the heaviest brown dwarfs and the lightest stars can have subtle differences in mass. Despite this, they have different fates: some will quickly go out and cool down, while others will shine for billions of years."
Better differentiation of stars from brown dwarfs could also help astronomers determine how many of these celestial bodies there are in our galaxy.
“We're wondering if stars and brown dwarfs exist in the same proportions to each other in star-forming regions, which in turn will help us understand the overall habitability of the Galaxy,” explains Alicia Weinberg of the Carnegie Institution, who also participated in the study.