A new parallax measurement for the coldest known brown dwarf

K. L. Luhman, T. L. Esplin

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


WISE J085510.83-071442.5 was recently discovered as the coldest known brown dwarf based on four epochs of images from the Wide-field Infrared Survey Explorer and the Spitzer Space Telescope. We have improved the accuracy of its parallax measurement by obtaining two additional epochs of Spitzer astrometry. We derive a parallactic distance of 2.31 ± 0.08 pc, which continues to support its rank as the fourth closest known system to the Sun when compared to WISE J104915.57-531906.1 AB (2.02 ± 0.02 pc) and Wolf 359 (2.386 ± 0.012 pc). The new constraint on the absolute magnitude at 4.5 μm indicates an effective temperature of 235-260 K based on four sets of theoretical models. We also show the updated positions of WISE J085510.83-071442.5 in two color-magnitude diagrams. Whereas Faherty and coworkers cited its location in M W2 versus J - W2 as evidence of water clouds, we find that those data can be explained instead by cloudless models that employ non-equilibrium chemistry.

Original languageEnglish (US)
Article number6
JournalAstrophysical Journal
Issue number1
StatePublished - Nov 20 2014

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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