We are conducting a proper-motion survey for young brown dwarfs in the Taurus–Auriga molecular cloud based on the Pan-STARRS1 3 \pi Survey .
Our search uses multi-band photometry and astrometry to select candidates , and is wider ( 370 deg ^ { 2 } ) and deeper ( down to \approx 3 M _ { Jup } ) than previous searches .
We present here our search methods and spectroscopic follow-up of our high-priority candidates .
Since extinction complicates spectral classification , we have developed a new approach using low-resolution ( R \approx 100 ) near-infrared spectra to quantify reddening-free spectral types , extinctions , and gravity classifications for mid-M to late-L ultracool dwarfs ( \approx 100 - 3 M _ { Jup } in Taurus ) .
We have discovered 25 low-gravity ( vl-g ) and the first 11 intermediate-gravity ( int-g ) substellar ( M6–L1 ) members of Taurus , constituting the largest single increase of Taurus brown dwarfs to date .
We have also discovered 1 new Pleiades member and 13 new members of the Perseus OB2 association , including a candidate very wide separation ( 58 kAU ) binary .
We homogeneously reclassify the spectral types and extinctions of all previously known Taurus brown dwarfs .
Altogether our discoveries have thus far increased the substellar census in Taurus by \approx 40 \% and added three more L-type members ( \approx 5 - 10 M _ { Jup } ) .
Most notably , our discoveries reveal an older ( > 10 Myr ) low-mass population in Taurus , in accord with recent studies of the higher-mass stellar members .
The mass function appears to differ between the younger and older Taurus populations , possibly due to incompleteness of the older stellar members or different star formation processes .