Web Extra: Brown dwarfs take center stage

In the two decades since astronomers discovered the first brown dwarf — Teide 1 in the Pleiades star cluster — they have found more than a thousand. These enigmatic objects, which don’t have enough mass to ignite hydrogen fusion and thus become full-fledged stars, glow mostly by radiating the heat from their formation. Because they are so faint, all those that lurk in the solar neighborhood escaped detection until the 21st century.

The table below lists all known brown dwarfs within 15 light-years of Earth. These objects are classified as L, T, or Y, running from hottest to coolest. The nearest — a pair of objects dubbed Luhman 16A and B some 6.6 light-years away — rank as the fifth and sixth closest objects to home. Only the triple-star system Alpha Centauri and Barnard’s Star are nearer. One final note: A fine line exists between the smallest hydrogen-burning stars and the largest brown dwarfs, so it is quite possible that a few M-class “stars” not listed here are actually brown dwarfs.

Name	Distance	Right   Ascension	Declination	Class	Year of   Discovery
Luhman 16A	6.6	10h49.3m	–53°19'	L8	2013
Luhman 16B	6.6	10h49.3m	–53°19'	T1	2013
WISE 0855-0714	7.2	8h55.2m	–7°15'	Y	2014
WISE 1506+7027	11.1	15h06.8m	70°28'	T6	2011
Epsilon Indi B	11.8	22h04.2m	–56°47'	T1	2003
Epsilon Indi C	11.8	22h04.2m	–56°47'	T6	2003
WISE 0350-5658	12.1	3h50.0m	–56°59'	Y1	2011
SCR 1845-6357 B	12.6	18h45.0m	–63°58'	T6	2006
UGP 0722-0540	13.4	7h22.5m	–5°41'	T9	2010

Distance  in light-years; Right ascension and declination in 2000.0 coordinates.