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tag:blogger.com,1999:blog-1014682403395027648.post-4427504531677220260: Two Tight Pairs of Low-Mass Binary Brown Dwarfs
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Direct link Two Tight Pairs of Low-Mass Binary Brown Dwarfs

17 Jul 2014, 22:00 UTC Figure 1: Artist’s impression of a brown dwarf. Heat from its warm interior “leaks” out through gaps in its cloud coverage. A cool brown dwarf would resemble Jupiter more than it would resemble a star.Brown dwarfs are substellar objects that span the gap between the most massive planets and the least massive stars. Like stars, brown dwarfs can also come in pairs. Using a technique known as gravitational microlensing, Choi et al. (2013) reported the discovery of two pairs of very low-mass binary brown dwarfs identified as OGLE-2009-BLG-151 and OGLE-2011-BLG-0420. Gravitational microlensing is observed when the gravity of an intervening object (lens) magnifies the light from a background star (source). It happens as the intervening object crosses the line-of-sight between the observer and the background star.OGLE-2009-BLG-151 was first detected by the Optical Gravitational Lensing Experiment (OGLE) group and then independently detected by the Microlensing Observations in Astrophysics (MOA) group in 2009, hence its alternate designation - “MOA-2009-BLG-232”. The other gravitational microlensing event, OGLE-2011-BLG-0420, was detected by the OGLE group in 2011. A number of ground-based telescopes also provided follow-up observations for both gravitational microlensing events.Figure 2: Light-curves of the binary brown dwarf gravitational microlensing events OGLE-2009-BLG-151 and OGLE-2011-BLG-0420. Choi et ...

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