2020-11-04T20:58:33.239Z 2016-11-02T16:04:07.000Z Y dwarfs Y brown dwarfs Y dwarf stars A type of ultra-cool brown dwarf with an effective temperature lower than 500 K. Near infrared spectra of these objects show deep absorption bands of H_{2}O and CH_4. So far only seven brown dwarf candidates belonging to this class have been found, all Y0 subtypes. These objects are very dim, with H magnitudes 19-23. The precise definition of the Y class requires new findings in the future about these objects. Y-type brown dwarfs