Deep z-band observations of the coolest y dwarf
Kopytova, Taisiya G.; Crossfield, Ian J M; Deacon, Niall R.; Brandner, Wolfgang; Buenzli, Esther; Bayo, Amelia; Schlieder, Joshua E.; Manjavacas, Elena; Biller, Beth A.; Kopon, Derek
Citation: Kopytova , T G , Crossfield , I J M , Deacon , N R , Brandner , W , Buenzli , E , Bayo , A , Schlieder , J E , Manjavacas , E , Biller , B A & Kopon , D 2014 , ' Deep z-band observations of the coolest y dwarf ' The Astrophysical Journal , vol 797 , no. 1 , 3 . DOI: 10.1088/0004-637X/797/1/3
WISE J085510.83-071442.5 (hereafter, WISE 0855-07) is the coolest Y dwarf known to date and is located at a distance of 2.31 ± 0.08 pc, giving it the fourth largest parallax of any known star or brown dwarf system. We report deep z-band observations of WISE 0855-07 using FORS2 on UT1/Very Large Telescope. We do not detect any counterpart to WISE 0855-07 in our z-band images and estimate a brightness upper limit of AB mag > 24.8 (F ν <0.45 μJy) at 910 ± 65 nm with 3σ confidence. We combine our z-band upper limit with previous near- and mid-infrared photometry to place constraints on the atmospheric properties of WISE 0855-07 via comparison to models which implement water clouds in the atmospheres of T eff <300 K substellar objects. We find that none of the available models that implement water clouds can completely reproduce the observed spectral energy distribution of WISE 0855-07. Every model significantly disagrees with the (3.6 μm/4.5 μm) flux ratio and at least one other bandpass. Since methane is predicted to be the dominant absorber at 3-4 μm, these mismatches might point to an incorrect or incomplete treatment of methane in current models. We conclude that (a) WISE0855-07 has T eff 200-250 K, (b)
Taisiya G. Kopytova, et al., “Deep z-band observations of the coolest y dwarf”, The Astrophysical Journal, Vol. 797(1), November 2014. © 2014. The American Astronomical Society.
This item appears in the following Collection(s)
Your requested file is now available for download. You may start your download by selecting the following link: test