Brown Dwarfs: The Spectroscopy of Sub-stellar Objects

The most massive planet is nearly 6 times lighter than the least massive star. In between is the realm of brown dwarfs.  In 1995 both the first brown dwarf and the first exoplanet were discovered. Since then we have found hundreds of each, and have learned quite a bit. Recent infrared surveys have now probed the whole sky to very faint levels. Recent discoveries include the coolest and closest brown dwarfs. This allows us to push to very cool objects – the spectral sequence has added 3 to the original 7: L, T, and Y dwarfs. We can actually see brown dwarfs, whereas exoplanets are almost all detected only indirectly. Brown dwarfs overlap in temperature with young massive exoplanets, so their spectra look much more like planets than stars. I will give a flavor of how spectroscopy can be used to study what the atmospheres and physical properties of such objects are like.

Speaker: Dr. Gibor Basri, UC Berkeley