How to distinguish between stars and brown dwarfs

Washington – Researchers have found clear observational evidence for the theoretically predicted break between very low mass stars and brown dwarfs.

The data came from the SOAR (Southern Astrophysical Research) 4.1-m telescope and the SMARTS (Small and Moderate Aperture Research Telescope System) 0.9-m telescope at the Cerro Tololo Inter-American Observatory (CTIO) in Chile.

Lead author, Dr. Sergio Dieterich, said that in order to distinguish stars from brown dwarfs they measured the light from each object thought to lie close to the stellar/brown dwarf boundary.

He said that they also carefully measured the distances to each object, asserting that they could then calculate their temperatures and radii using basic physical laws, and found the location of the smallest objects we observed.

He said that they see that radius decreases with decreasing temperature, as expected for stars, until they reach a temperature of about 2,100 K, adding that there they see a gap with no objects, and then the radius starts to increase with decreasing temperature, as they expect for brown dwarfs.

Dr. Todd Henry, another author, said that they can now point to a temperature (2,100 K), radius (8.7 per cent that of our Sun), and luminosity (1/8000 of the Sun) and say ‘the main sequence ends there’ and we can identify a particular star (with the designation 2MASS J0513-1403) as a representative of the smallest stars.

The research is set to be published in the Astronomical Journal.