Abstract
Context. Nearby isolated planetary mass objects are beginning to be discovered, but their individual properties are poorly constrained because their low surface temperatures and strong molecular self-absorption make them extremely faint. Aims. We aimed to detect the near-infrared emission of the coldest brown dwarf (BD) found so far, WISE0855-0714, located ~2.2 pc away, and to improve its temperature estimate (Teff = 225-260 K) from a comparison with state-of-the-art models of BD atmospheres. Methods. We observed the field containing WISE0855-0714 with HAWK-I at the VLT in the Y band. For BDs with Teff< 500 K theoretical models predict strong signal (or rather less molecular absorption) in this band. Results. WISE0855-0714 was not detected in our Y-band images, thus placing an upper limit on its brightness to Y> 24.4 mag at 3σ level, leading to Y-[4.5] > 10.5. Combining this limit with previous detections and upper limits at other wavelengths, WISE0855-0714 is confirmed as the reddest BD detected, further supporting its status as the coldest known brown dwarf.
Original language | English |
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Article number | L8 |
Journal | Astronomy and Astrophysics |
Volume | 570 |
DOIs | |
Publication status | Published - 1 Oct 2014 |
Keywords
- Brown dwarfs
- Infrared: stars
- Proper motions
- Solar neighborhood
- Stars: individual: WISE 0855-0714
- Stars: low-mass
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science