A New Parallax Measurement for the Coldest Known Brown Dwarf
Abstract
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.
Based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA.- Publication:
-
The Astrophysical Journal
- Pub Date:
- November 2014
- DOI:
- 10.1088/0004-637X/796/1/6
- arXiv:
- arXiv:1409.5899
- Bibcode:
- 2014ApJ...796....6L
- Keywords:
-
- brown dwarfs;
- infrared: stars;
- proper motions;
- solar neighborhood;
- stars: low-mass;
- Astrophysics - Astrophysics of Galaxies;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- Astrophysical Journal, in press