Parallaxes and Infrared Photometry of three Y0 dwarfs

R. L. Smart, Dániel Apai, J. Davy Kirkpatrick, S. K. Leggett, F. Marocco, Jane E. Morrison, H. R. A. Jones, D. Pinfield, P. Tremblin, D. S. Amundsen

Published 2017-03-30Version 1

We have followed up the three Y0 dwarfs WISEPA J041022.71+150248.5, WISEPA J173835.53+273258.9 and WISEPC J205628.90+145953.3 using the UKIRT/WFCAM telescope/instruments. We find parallaxes that are more consistent and accurate than previously published values. We estimate absolute magnitudes in photometric pass-bands from $Y$ to $W3$ and find them to be consistent between the three Y0 dwarfs indicating the inherent cosmic absolute magnitude spread of these objects is small. We examine the MKO $J$ magnitudes over the four year time line and find small but significant monotonic variations. Finally we estimate physical parameters from a comparison of spectra and parallax to equilibrium and non-equilibrium models finding values consistent with solar metallicity, an effective temperature of 450-475\,K and log~g of 4.0-4.5.