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Brown dwarf stars, often referred to as “failed stars,” are heavier than most planets but not massive enough to generate nuclear fusion reactions in their cores like true stars. Utilizing data from the Spitzer Space Telescope, NASA astronomers have identified three sub-stellar objects of this type. Notably, these objects are spinning faster than any previously known brown dwarf.
Designated as 2MASS J0348−6022, 2MASS J1219-3128, and 2MASS J0407-1546, these objects have sizes comparable to Earth but are 40 to 70 times heavier. They are situated at distances of 29.66 and 119 light-years from Earth, within the constellations Sculptor, Phoenix, and Taurus.
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The rotational speed of 2MASS J0348−6022 compared to Earth.
Led by NASA astronomer Megan Tannock, the research team measured changes in the light emitted by the brown dwarf stars caused by the Doppler effect. They employed a computer model to calculate the rotation speeds of these objects. The results indicate that these three celestial bodies are self-rotating at speeds reaching up to 360,000 km/h (100 km/s), completing a full rotation in just one hour.
To put this in perspective, this speed is ten times faster than Earth’s, and more than 30% faster than the previously recorded fastest spinning brown dwarf. The study underscores that this speed nears the rotational limit beyond which the objects would disintegrate due to centripetal force.
“It would be spectacular if a brown dwarf were to spin so fast that it ejected its atmosphere into space, but so far, we have not found an object like that,” Tannock noted.
Despite sharing similar sizes and rotation speeds, the three brown dwarfs studied exhibit significant differences in temperature, ranging from hot to cold to an intermediate state.
The detailed study has been published in the Astronomical Journal. In the next phase, Tannock and her colleagues aim to conduct further observations to determine if these fastest-spinning brown dwarf stars have any natural “braking” mechanisms.