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A brown dwarf orbiting an M-dwarf : MOA 2009-BLG-411L

Bachelet, E.; ...; Dominis Prester, Dijana; ...; Zimmer, F.
A brown dwarf orbiting an M-dwarf : MOA 2009-BLG-411L // Astronomy & astrophysics, 547 (2012), A55-1 doi:10.1051/0004-6361/201219765 (međunarodna recenzija, članak, znanstveni)

A brown dwarf orbiting an M-dwarf : MOA 2009-BLG-411L

Bachelet, E. ; ... ; Dominis Prester, Dijana ; ... ; Zimmer, F.

Astronomy & astrophysics (0004-6361) 547 (2012); A55-1

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

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.

Izvorni jezik

Znanstvena područja

I The MiNDSTEp Consortium.


Projekt / tema
316-0000000-2824 - Dijagnostika i fizička svojstva cirkumstelarne tvari (Dubravka Kotnik-Karuza, )

Sveučilište u Rijeci - Odjel za fiziku

Autor s matičnim brojem:
Dijana Dominis Prester, (241452)

Časopis indeksira:

  • Current Contents Connect (CCC)
  • Web of Science Core Collection (WoSCC)
    • SCI-EXP, SSCI i/ili A&HCI
  • Scopus