Journal article
A brown dwarf orbiting an M-dwarf: MOA 2009–BLG–411L
Astronomy and astrophysics (Berlin), Vol.547, p.A55
11/01/2012
DOI: 10.1051/0004-6361/201219765
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.
Details
- Title: Subtitle
- A brown dwarf orbiting an M-dwarf: MOA 2009–BLG–411L
- Creators
- E. Bachelet - Université de ToulouseP. Fouqué - Université de ToulouseC. Han - Chungbuk National UniversityA. Gould - The Ohio State UniversityM. D. Albrow - University of CanterburyJ.-P. Beaulieu - Institut d'Astrophysique de ParisE. Bertin - Institut d'Astrophysique de ParisI. A. Bond - Massey UniversityG. W. Christie - Carter ObservatoryD. Heyrovský - Charles UniversityK. Horne - University of St AndrewsU. G. Jørgensen - University of CopenhagenD. Maoz - Tel Aviv UniversityM. Mathiasen - University of CopenhagenN. Matsunaga - National Astronomical Observatory of JapanJ. McCormick - Carter ObservatoryJ. Menzies - South African Radio Astronomy ObservatoryD. Nataf - The Ohio State UniversityT. Natusch - Auckland University of TechnologyN. Oi - The Graduate University for Advanced Studies, SOKENDAIN. Renon - Université Toulouse III - Paul SabatierY. Tsapras - Queen Mary University of LondonA. Udalski - University of WarsawJ. C. Yee - The Ohio State UniversityV. Batista - Institut d'Astrophysique de ParisD. P. Bennett - Microlensing Observations in Astrophysics, http://www.phys.canterbury.ac.nz/moaS. Brillant - European Southern ObservatoryJ. A. R. Caldwell - SpurA. Cassan - Institut d'Astrophysique de ParisA. Cole - University of TasmaniaK. H. Cook - Lawrence Livermore National LaboratoryC. Coutures - Institut d'Astrophysique de ParisS. Dieters - Institut d'Astrophysique de ParisM. Dominik - University of St AndrewsD. Dominis Prester - University of RijekaJ. Donatowicz - University of ViennaJ. Greenhill - University of TasmaniaN. Kains - European Southern ObservatoryS. R. Kane - NASA Exoplanet Science InstituteJ.-B. Marquette - Institut d'Astrophysique de ParisR. Martin - Perth ObservatoryK. R. Pollard - University of CanterburyK. C. Sahu - Space Telescope Science InstituteR. A. Street - Las Cumbres Observatory Global Telescope NetworkJ. Wambsganss - Microlensing Network for the Detection of Small Terrestrial Exoplanets, http://www.mindstep-science.orgA. Williams - Perth ObservatoryM. Zub - Heidelberg UniversityM. Bos - Carter ObservatorySubo Dong - Institute for Advanced StudyJ. Drummond - Possum ObservatoryB. S. Gaudi - The Ohio State UniversityD. GraffJ. Janczak - The Ohio State UniversityS. Kaspi - Tel Aviv UniversityS. Kozłowski - The Ohio State UniversityC.-U. Lee - Korea Astronomy and Space Science InstituteL. A. G. Monard - Bronberg ObservatoryJ. A. Muñoz - Universitat de ValènciaB.-G. Park - Korea Astronomy and Space Science InstituteR. W. Pogge - The Ohio State UniversityD. Polishook - Tel Aviv UniversityA. Shporer - Tel Aviv UniversityF. Abe - Osaka Health Science UniversityC. S. Botzler - University of AucklandA. Fukui - National Astronomical Observatory of JapanK. Furusawa - Osaka UniversityJ. B. Hearnshaw - University of CanterburyY. Itow - Osaka Health Science UniversityA. V. Korpela - Mount John Observatory, PO Box 56, 8770 Lake Tekapo, New ZealandC. H. Ling - Massey UniversityK. Masuda - Osaka Health Science UniversityY. Matsubara - Osaka Health Science UniversityN. Miyake - Osaka Health Science UniversityY. Muraki - Konan UniversityK. Ohnishi - National Institute of Technology, Nagano CollegeN. J. Rattenbury - Robotic Telescope Network, http://robonet.lcogt.netTo Saito - College of Industrial TechnologyD. Sullivan - Mount Saint Vincent UniversityT. Sumi - Osaka UniversityD. Suzuki - Osaka Health Science UniversityW. L. Sweatman - Massey UniversityP. J. Tristram - University of CambridgeK. Wada - Osaka UniversityA. Allan - University of ExeterM. F. Bode - Liverpool John Moores UniversityD. M. Bramich - European Southern ObservatoryN. Clay - Liverpool John Moores UniversityS. N. Fraser - Liverpool John Moores UniversityE. Hawkins - Las Cumbres Observatory Global Telescope NetworkE. Kerins - University of ManchesterT. A. Lister - Las Cumbres Observatory Global Telescope NetworkC. J. Mottram - Liverpool John Moores UniversityE. S. Saunders - Las Cumbres Observatory Global Telescope NetworkC. Snodgrass - European Southern ObservatoryI. A. Steele - Liverpool John Moores UniversityP. J. Wheatley - University of WarwickV. Bozza - University of SalernoP. Browne - University of St AndrewsM. J. Burgdorf - Ames Research CenterS. Calchi Novati - Dipartimento di Fisica, Università di Salerno, Fisciano, INFN, sez. di Napoli, IIASS, Vietri sul Mare, ItalyS. Dreizler - University of GöttingenF. Finet - University of LiègeM. Glitrup - Aarhus UniversityF. Grundahl - Aarhus UniversityK. Harpsøe - University of CopenhagenF. V. Hessman - University of GöttingenT. C. Hinse - Korea Astronomy and Space Science InstituteM. Hundertmark - University of GöttingenC. Liebig - University of St AndrewsG. Maier - Astronomisches Rechen-Institut (ARI), Zentrum für Astronomie der Universität Heidelberg (ZAH), Mönchhofstrasse 12ŋ-14, 69120 Heidelberg, GermanyL. Mancini - Heidelberg UniversityS. Rahvar - Sharif University of TechnologyD. Ricci - University of LiègeG. Scarpetta - University of SalernoJ. Skottfelt - University of CopenhagenJ. Southworth - Keele UniversityJ. Surdej - Institut d’Astrophysique et de Géophysique, Allée du 6 Août, Sart Tilman, Bât. B5c, 4000 Liège, BelgiumF. Zimmer - Heidelberg UniversityMiNDSTEp 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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