'Rare' brown dwarf discovery provides benchmark for future exoplanet research

A team of researchers have directly imaged a very rare type of brown dwarf that can serve as a benchmark for studying objects with masses that lie between stars and planets.

Initial data came from the TRENDS (TaRgetting bENchmark-objects with Doppler Spectroscopy) high-contrast imaging survey that uses adaptive optics and related technologies to target older, faint objects orbiting nearby stars, and precise measurements were made at the W. M. Keck Observatory on the summit of Mauna Kea, Hawaii. Brown dwarfs emit little light because they do not burn hydrogen and cool rapidly.

Justin R. Crepp, the Freimann Assistant Professor of Physics at the University of Notre Dame, said they could provide a link between our understanding of low-mass stars and smaller objects such as planets.

HD 19467 B, a T-dwarf, is a very faint companion to a nearby Sun-like star, more than 100,000 times as dim as its host. Its distance is known precisely, and the discovery also enables researchers to place strong constraints on important factors such as its mass, orbit, age, and chemical composition without reference to the spectrum of light received from its surface.

Precise radial velocity measurements were obtained using the HIRES instrument installed on Keck Observatory's 10-meter, Keck I telescope. The observations, which span 17 years starting from 1996, show a long-term acceleration, indicating that a low-mass companion was "tugging" on the parent star. Follow-up high-contrast imaging observations were then taken in 2012 using the NIRC2 instrument on the Keck II telescope with the adaptive optics system revealing the companion as shown above.

The paper has been published in the Astrophysical Journal.