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

E. Bachelet; P. Fouqué; C. Han; A. Gould; M. D. Albrow; J.-P. Beaulieu; E. Bertin; I. A. Bond; G. W. Christie; D. Heyrovský; K. Horne; U. G. Jørgensen; D. Maoz; M. Mathiasen; N. Matsunaga; J. McCormick; J. Menzies; D. Nataf; T. Natusch; N. Oi; N. Renon; Y. Tsapras; A. Udalski; J. C. Yee; V. Batista; D. P. Bennett; S. Brillant; J. A. R. Caldwell; A. Cassan; A. Cole; K. H. Cook; C. Coutures; S. Dieters; M. Dominik; D. Dominis Prester; J. Donatowicz; J. Greenhill; N. Kains; S. R. Kane; J.-B. Marquette; R. Martin; K. R. Pollard; K. C. Sahu; R. A. Street; J. Wambsganss; A. Williams; M. Zub; M. Bos; Subo Dong; J. Drummond; B. S. Gaudi; D. Graff; J. Janczak; S. Kaspi; S. Kozłowski; C.-U. Lee; L. A. G. Monard; J. A. Muñoz; B.-G. Park; R. W. Pogge; D. Polishook; A. Shporer; F. Abe; C. S. Botzler; A. Fukui; K. Furusawa; J. B. Hearnshaw; Y. Itow; A. V. Korpela; C. H. Ling; K. Masuda; Y. Matsubara; N. Miyake; Y. Muraki; K. Ohnishi; N. J. Rattenbury; To Saito; D. Sullivan; T. Sumi; D. Suzuki; W. L. Sweatman; P. J. Tristram; K. Wada; A. Allan; M. F. Bode; D. M. Bramich; N. Clay; S. N. Fraser; E. Hawkins; E. Kerins; T. A. Lister; C. J. Mottram; E. S. Saunders; C. Snodgrass; I. A. Steele; P. J. Wheatley; V. Bozza; P. Browne; M. J. Burgdorf; S. Calchi Novati; S. Dreizler; F. Finet; M. Glitrup; F. Grundahl; K. Harpsøe; F. V. Hessman; T. C. Hinse; M. Hundertmark; C. Liebig; G. Maier; L. Mancini; S. Rahvar; D. Ricci; G. Scarpetta; J. Skottfelt; J. Southworth; J. Surdej; F. Zimmer; MiNDSTEp Consortium

doi:10.1051/0004-6361/201219765

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

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

E. Bachelet, P. Fouqué, C. Han, A. Gould, M. D. Albrow, J.-P. Beaulieu, E. Bertin, I. A. Bond, G. W. Christie, D. Heyrovský, …

Astronomy and astrophysics (Berlin), Vol.547, p.A55

11/01/2012

DOI: 10.1051/0004-6361/201219765

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Abstract

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 R⊙. 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 M⊙ orbiting a primary M-star of mass MP = 0.18 M⊙. 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.

binaries: general

gravitational lensing: micro

stars: individual: MOA 2009-BLG-411L

Details

Title: Subtitle: A brown dwarf orbiting an M-dwarf: MOA 2009–BLG–411L
Creators: E. Bachelet - Université de Toulouse
P. Fouqué - Université de Toulouse
C. Han - Chungbuk National University
A. Gould - The Ohio State University
M. D. Albrow - University of Canterbury
J.-P. Beaulieu - Institut d'Astrophysique de Paris
E. Bertin - Institut d'Astrophysique de Paris
I. A. Bond - Massey University
G. W. Christie - Carter Observatory
D. Heyrovský - Charles University
K. Horne - University of St Andrews
U. G. Jørgensen - University of Copenhagen
D. Maoz - Tel Aviv University
M. Mathiasen - University of Copenhagen
N. Matsunaga - National Astronomical Observatory of Japan
J. McCormick - Carter Observatory
J. Menzies - South African Radio Astronomy Observatory
D. Nataf - The Ohio State University
T. Natusch - Auckland University of Technology
N. Oi - The Graduate University for Advanced Studies, SOKENDAI
N. Renon - Université Toulouse III - Paul Sabatier
Y. Tsapras - Queen Mary University of London
A. Udalski - University of Warsaw
J. C. Yee - The Ohio State University
V. Batista - Institut d'Astrophysique de Paris
D. P. Bennett - Microlensing Observations in Astrophysics, http://www.phys.canterbury.ac.nz/moa
S. Brillant - European Southern Observatory
J. A. R. Caldwell - Spur
A. Cassan - Institut d'Astrophysique de Paris
A. Cole - University of Tasmania
K. H. Cook - Lawrence Livermore National Laboratory
C. Coutures - Institut d'Astrophysique de Paris
S. Dieters - Institut d'Astrophysique de Paris
M. Dominik - University of St Andrews
D. Dominis Prester - University of Rijeka
J. Donatowicz - University of Vienna
J. Greenhill - University of Tasmania
N. Kains - European Southern Observatory
S. R. Kane - NASA Exoplanet Science Institute
J.-B. Marquette - Institut d'Astrophysique de Paris
R. Martin - Perth Observatory
K. R. Pollard - University of Canterbury
K. C. Sahu - Space Telescope Science Institute
R. A. Street - Las Cumbres Observatory Global Telescope Network
J. Wambsganss - Microlensing Network for the Detection of Small Terrestrial Exoplanets, http://www.mindstep-science.org
A. Williams - Perth Observatory
M. Zub - Heidelberg University
M. Bos - Carter Observatory
Subo Dong - Institute for Advanced Study
J. Drummond - Possum Observatory
B. S. Gaudi - The Ohio State University
D. Graff
J. Janczak - The Ohio State University
S. Kaspi - Tel Aviv University
S. Kozłowski - The Ohio State University
C.-U. Lee - Korea Astronomy and Space Science Institute
L. A. G. Monard - Bronberg Observatory
J. A. Muñoz - Universitat de València
B.-G. Park - Korea Astronomy and Space Science Institute
R. W. Pogge - The Ohio State University
D. Polishook - Tel Aviv University
A. Shporer - Tel Aviv University
F. Abe - Osaka Health Science University
C. S. Botzler - University of Auckland
A. Fukui - National Astronomical Observatory of Japan
K. Furusawa - Osaka University
J. B. Hearnshaw - University of Canterbury
Y. Itow - Osaka Health Science University
A. V. Korpela - Mount John Observatory, PO Box 56, 8770 Lake Tekapo, New Zealand
C. H. Ling - Massey University
K. Masuda - Osaka Health Science University
Y. Matsubara - Osaka Health Science University
N. Miyake - Osaka Health Science University
Y. Muraki - Konan University
K. Ohnishi - National Institute of Technology, Nagano College
N. J. Rattenbury - Robotic Telescope Network, http://robonet.lcogt.net
To Saito - College of Industrial Technology
D. Sullivan - Mount Saint Vincent University
T. Sumi - Osaka University
D. Suzuki - Osaka Health Science University
W. L. Sweatman - Massey University
P. J. Tristram - University of Cambridge
K. Wada - Osaka University
A. Allan - University of Exeter
M. F. Bode - Liverpool John Moores University
D. M. Bramich - European Southern Observatory
N. Clay - Liverpool John Moores University
S. N. Fraser - Liverpool John Moores University
E. Hawkins - Las Cumbres Observatory Global Telescope Network
E. Kerins - University of Manchester
T. A. Lister - Las Cumbres Observatory Global Telescope Network
C. J. Mottram - Liverpool John Moores University
E. S. Saunders - Las Cumbres Observatory Global Telescope Network
C. Snodgrass - European Southern Observatory
I. A. Steele - Liverpool John Moores University
P. J. Wheatley - University of Warwick
V. Bozza - University of Salerno
P. Browne - University of St Andrews
M. J. Burgdorf - Ames Research Center
S. Calchi Novati - Dipartimento di Fisica, Università di Salerno, Fisciano, INFN, sez. di Napoli, IIASS, Vietri sul Mare, Italy
S. Dreizler - University of Göttingen
F. Finet - University of Liège
M. Glitrup - Aarhus University
F. Grundahl - Aarhus University
K. Harpsøe - University of Copenhagen
F. V. Hessman - University of Göttingen
T. C. Hinse - Korea Astronomy and Space Science Institute
M. Hundertmark - University of Göttingen
C. Liebig - University of St Andrews
G. Maier - Astronomisches Rechen-Institut (ARI), Zentrum für Astronomie der Universität Heidelberg (ZAH), Mönchhofstrasse 12ŋ-14, 69120 Heidelberg, Germany
L. Mancini - Heidelberg University
S. Rahvar - Sharif University of Technology
D. Ricci - University of Liège
G. Scarpetta - University of Salerno
J. Skottfelt - University of Copenhagen
J. Southworth - Keele University
J. Surdej - Institut d’Astrophysique et de Géophysique, Allée du 6 Août, Sart Tilman, Bât. B5c, 4000 Liège, Belgium
F. Zimmer - Heidelberg University
MiNDSTEp Consortium
Resource Type: Journal article
Publication Details: Astronomy and astrophysics (Berlin), Vol.547, p.A55
Publisher: EDP Sciences
DOI: 10.1051/0004-6361/201219765
ISSN: 0004-6361
eISSN: 1432-0746
Number of pages: 12
Language: English
Date published: 11/01/2012
Academic Unit: Physics and Astronomy
Record Identifier: 9984701830702771

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