New Y and T dwarfs from WISE identified by Methane Imaging

摘要: We identify new Y- and T-type brown dwarfs from the WISE All Sky data release using images obtained in filters that divide traditional near-infrared H J bands into two halves -- specifically CH4s & CH4l J2 J3 J. This proves to be very effective at identifying cool via detection of their methane absorption, as well providing preliminary classification colours WISE-to-near-infrared colours. New updated calibrations between T/Y spectral types CH4s-CH4l, J3-W2, CH4s-W2 are derived, producing estimates good a few sub-types. present photometry for large sample T Y these filters, together with spectroscopy 23 ultra-cool - twenty one dwarfs. further 8 dwarfs, which we have high confidence based on photometry. find that, objects observed 4m-class telescope band magnitudes ~20 or brighter, CH4s-CH4l is more powerful colour detecting then estimating types. Due lower sky background J-band, useful fainter J>22. The J3-J2 poor But fortunately, once confirms an object dwarf, J3-W2 approximate