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Pregled bibliografske jedinice broj: 619104


Autori: Bachelet, E.; ...; Dominis Prester, Dijana; ...; Zimmer, F.
Naslov: A brown dwarf orbiting an M-dwarf : MOA 2009-BLG-411L
Izvornik: Astronomy & astrophysics (0004-6361) 547 (2012); A55-1-A55-12
Vrsta rada: članak
Ključne riječi: binaries: general; gravitational lensing: micro; stars: individual: MOA 2009-BLG-411L
Context. Caustic crossing is the clearest signature of binary lenses in microlensing. In the present context, this signature is diluted by the large source star but a detailed analysis has allowed the companion signal to be extracted. Aims: MOA 2009-BLG-411 was detected on August 5, 2009 by the MOA-Collaboration. Alerted as a high-magnification event, it was sensitive to planets. Suspected anomalies in the light curve were not confirmed by a real-time model, but further analysis revealed small deviations from a single lens extended source fit. Methods: Thanks to observations by all the collaborations, this event was well monitored. We first decided to characterize the source star properties by using a more refined method than the classical one: we measure the interstellar absorption along the line of sight in five different passbands (VIJHK). Secondly, we model the lightcurve by using the standard technique: make (s, q, α) grids to look for local minima and refine the results by using a downhill method (Markov chain Monte Carlo). Finally, we use a Galactic model to estimate the physical properties of the lens components. Results: We find that the source star is a giant G star with radius 9 Rsun. The grid search gives two local minima, which correspond to the theoretical degeneracy s ≡ s-1. We find that the lens is composed of a brown dwarf secondary of mass MS = 0.05 Msun orbiting a primary M-star of mass MP = 0.18 Msun. We also reveal a new mass-ratio degeneracy for the central caustics of close binaries. Conclusions: As far as we are aware, this is the first detection using the microlensing technique of a binary system in our Galaxy composed of an M-star and a brown dwarf.
Projekt / tema: 316-0000000-2824
Izvorni jezik: ENG
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Kategorija: Znanstveni
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Broj citata:
DOI: 10.1051/0004-6361/201219765
URL cjelovitog teksta:
Google Scholar: A brown dwarf orbiting an M-dwarf : MOA 2009-BLG-411L
Upisao u CROSBI: Dijana Dominis Prester (, 20. Vel. 2013. u 14:37 sati
i The MiNDSTEp Consortium.

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