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

Bachelet, E., Fouque, P., Han, C., Gould, A., Albrow, M. D., Beaulieu, J. -P., Bertin, E., Bond, I. A., Christie, G. W., Heyrovsky, D., Horne, K., Jorgensen, U. G., Maoz, D., Mathiasen, M., Matsunaga, N., McCormick, J., Menzies, J., Nataf, D., Natusch, T., Oi, N., Renon, N., Tsapras, Y., Udalski, A., Yee, J. C., Batista, V., Bennett, D. P., Brillant, S., Caldwell, J. A. R., Cassan, A., Cole, A., Cook, K. H., Coutures, C., Dieters, S., Dominik, M., Prester, D. Dominis, Donatowicz, J., Greenhill, J., Kains, N., Kane, S. R., Marquette, J. -B., Martin, R., Pollard, K. R., Sahu, K. C., Street, R. A., Wambsganss, J., Williams, A., Zub, M., Bos, M., Dong, Subo, Drummond, J., Gaudi, B. S., Graff, D., Janczak, J., Kaspi, S., Kozlowski, S., Lee, C. -U., Monard, L. A. G., Munoz, J. A., Park, B. -G., Pogge, R. W., Polishook, D., Shporer, A., Abe, F., Botzler, C. S., Fukui, A., Furusawa, K., Hearnshaw, J. B., Itow, Y., Korpela, A. V., Ling, C. H., Masuda, K., Matsubara, Y., Miyake, N., Muraki, Y., Ohnishi, K., Rattenbury, N. J., Saito, To., Sullivan, D., Sumi, T., Suzuki, D., Sweatman, W. L., Tristram, P. J., Wada, K., Allan, A., Bode, M. F., Bramich, D. M., Clay, N., Fraser, S. N., Hawkins, E., Kerins, E., Lister, T. A., Mottram, C. J., Saunders, E. S., Snodgrass, C., Steele, I. A., Wheatley, P. J., Bozza, V., Browne, P., Burgdorf, M. J., Novati, S. Calchi, Dreizler, S., Finet, F., Glitrup, M., Grundahl, F., Harpsoe, K., Hessman, F. V., Hinse, T. C., Hundertmark, M., Liebig, C., Maier, G., Mancini, L., Rahvar, S., Ricci, D., Scarpetta, G., Skottfelt, J., Southworth, J., Surdej, J. and Zimmer, F. (2012) A brown dwarf orbiting an M-dwarf: MOA 2009-BLG-411L. Astronomy and Astrophysics, 547 1-12. doi:10.1051/0004-6361/201219765


Author Bachelet, E.
Fouque, P.
Han, C.
Gould, A.
Albrow, M. D.
Beaulieu, J. -P.
Bertin, E.
Bond, I. A.
Christie, G. W.
Heyrovsky, D.
Horne, K.
Jorgensen, U. G.
Maoz, D.
Mathiasen, M.
Matsunaga, N.
McCormick, J.
Menzies, J.
Nataf, D.
Natusch, T.
Oi, N.
Renon, N.
Tsapras, Y.
Udalski, A.
Yee, J. C.
Batista, V.
Bennett, D. P.
Brillant, S.
Caldwell, J. A. R.
Cassan, A.
Cole, A.
Cook, K. H.
Coutures, C.
Dieters, S.
Dominik, M.
Prester, D. Dominis
Donatowicz, J.
Greenhill, J.
Kains, N.
Kane, S. R.
Marquette, J. -B.
Martin, R.
Pollard, K. R.
Sahu, K. C.
Street, R. A.
Wambsganss, J.
Williams, A.
Zub, M.
Bos, M.
Dong, Subo
Drummond, J.
Gaudi, B. S.
Graff, D.
Janczak, J.
Kaspi, S.
Kozlowski, S.
Lee, C. -U.
Monard, L. A. G.
Munoz, J. A.
Park, B. -G.
Pogge, R. W.
Polishook, D.
Shporer, A.
Abe, F.
Botzler, C. S.
Fukui, A.
Furusawa, K.
Hearnshaw, J. B.
Itow, Y.
Korpela, A. V.
Ling, C. H.
Masuda, K.
Matsubara, Y.
Miyake, N.
Muraki, Y.
Ohnishi, K.
Rattenbury, N. J.
Saito, To.
Sullivan, D.
Sumi, T.
Suzuki, D.
Sweatman, W. L.
Tristram, P. J.
Wada, K.
Allan, A.
Bode, M. F.
Bramich, D. M.
Clay, N.
Fraser, S. N.
Hawkins, E.
Kerins, E.
Lister, T. A.
Mottram, C. J.
Saunders, E. S.
Snodgrass, C.
Steele, I. A.
Wheatley, P. J.
Bozza, V.
Browne, P.
Burgdorf, M. J.
Novati, S. Calchi
Dreizler, S.
Finet, F.
Glitrup, M.
Grundahl, F.
Harpsoe, K.
Hessman, F. V.
Hinse, T. C.
Hundertmark, M.
Liebig, C.
Maier, G.
Mancini, L.
Rahvar, S.
Ricci, D.
Scarpetta, G.
Skottfelt, J.
Southworth, J.
Surdej, J.
Zimmer, F.
Title A brown dwarf orbiting an M-dwarf: MOA 2009-BLG-411L
Journal name Astronomy and Astrophysics   Check publisher's open access policy
ISSN 0004-6361
1432-0746
Publication date 2012-11
Sub-type Article (original research)
DOI 10.1051/0004-6361/201219765
Open Access Status DOI
Volume 547
Start page 1
End page 12
Total pages 12
Place of publication Les Ulis, France
Publisher E D P Sciences
Language eng
Formatted 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.
Keyword Binaries: general
Gravitational lensing: micro
Stars: individual: MOA 2009-BLG-411L
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Mathematics and Physics
 
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