Rare Brown Dwarf Discovery Aids Exoplanet Study

The discovery of a very rare type of brown dwarf substar could soon provide a better understanding of exoplanets.

A team based at the University of Notre Dame is studying data from the TaRgetting bENnchmark-objects with Doppler Spectroscopy (TRENDS) high-contrast imaging survey, which uses adaptive optics and related technologies to target older, faint objects orbiting nearby stars. The observations were made at the W.M. Keck Observatory on Mauna Kea in Hawaii.

A brown dwarf, which is a very faint companion to a nearby sunlike star, emits little light because it cools rapidly and does not burn hydrogen. The discovery enables researchers to place constraints on important factors such as mass, orbit, age and chemical composition without reference to the spectrum of light received from its surface.

A rare type of brown dwarf substar, as seen from the Keck Observatory. Courtesy Justin R. Crepp.

Scientists understand the light received from stars relatively well, but the spectra from planets is complicated. This brown T-dwarf (HD 19467 B) could serve as a benchmark for studying objects with masses that lie between stars and planets, and could provide a link between low-mass stars and smaller objects such as planets, said Justin R. Crepp, assistant professor of physics at the University of Notre Dame.

The researchers obtained precise radial velocity measurements with the HIRES (high-resolution Echelle spectrometer) instrument installed on the Keck 1 telescope.

“This object is old and cold, and will ultimately garner much attention as one of the most well-studied and scrutinized brown dwarfs detected to date,” he said. Continued follow-up observations will test theoretical atmospheric models, he added.

Eventually, researchers hope to directly image, understand and acquire the spectrum of Earth-like planets.

The research was published in The Astrophysical Journal.

For more information, visit physics.nd.edu.