@article{SackettAlbrowBeaulieuetal.2003,
  author    = {Sackett, Penny D. and Albrow, Michael D. and Beaulieu, Jean-Philippe and Caldwell, John A. R. and Coutures, C. and Dominik, M. and Greenhill, John and Hill, K. and Horne, Keith and Jorgensen, Uffe Grae and Kane, Stephen R. and Kubas, Daniel and Martin, Ralph and Menzies, J. W. and Pollard, K. R. and Sahu, K. C. and Wambsganß, Joachim and Watson, R. and Williams, A.},
  title     = {PLANET II : a microlensing and transit search for extrasolar planets},
  year      = {2003},
  abstract  = {Due to their extremely small luminosity compared to the stars they orbit, planets outside our own Solar System are extraordinarily difficult to detect directly in optical light. Careful photometric monitoring of distant stars, however, can reveal the presence of exoplanets via the microlensing or eclipsing effects they induce. The international PLANET collaboration is performing such monitoring using a cadre of semi-dedicated telescopes around the world. Their results constrain the number of gas giants orbiting 1-7 AU from the most typical stars in the Galaxy. Upgrades in the program are opening regions of ''exoplanet discovery space'' - toward smaller masses and larger orbital radii - that are inaccessible to the Doppler velocity technique.},
  language  = {en}
}
@article{CassanBeaulieuBrillantetal.2004,
  author    = {Cassan, A. and Beaulieu, Jean-Philippe and Brillant, Stephane and Coutures, C. and Dominik, M. and Donatowicz, J. and Jorgensen, Uffe Grae and Kubas, Daniel and Albrow, Michael D. and Caldwell, John A. R. and Fouque, P. and Greenhill, John and Hill, K. and Horne, Keith and Kane, Stephen R. and Martin, Ralph and Menzies, J. W. and Pollard, K. R. and Sahu, K. C. and Vinter, C. and Wambsganss, Joachim and Watson, R. and Williams, A. and Fendt, Christian and Hauschildt, P. and Heinmueller, Janine and Marquette, Jean-Baptiste and Thurl, C.},
  title     = {Probing the atmosphere of the bulge G5III star OGLE-2002-BUL-069 by analysis of microlensed H alpha line},
  year      = {2004},
  abstract  = {We discuss high-resolution, time-resolved spectra of the caustic exit of the binary microlensing event OGLE 2002-BLG-069 obtained with UVES on the VLT. The source star is a G5III giant in the Galactic Bulge. During such events, the source star is highly magnified, and a strong differential magnification around the caustic resolves its surface. Using an appropriate model stellar atmosphere generated by the PHOENIX v2.6 code we obtain a model light curve for the caustic exit and compare it with a dense set of photometric observations obtained by the PLANET microlensing follow up network. We further compare predicted variations in the Halpha equivalent width with those measured from our spectra. While the model and observations agree in the gross features, there are discrepancies suggesting shortcomings in the model, particularly for the Halpha line core, where we have detected amplified emission from the stellar chromosphere after the source star's trailing limb exited the caustic. This achievement became possible by the provision of the very efficient OGLE-III Early Warning System, a network of small telescopes capable of nearly-continuous round-the-clock photometric monitoring, on-line data reduction, daily near-real-time modelling in order to predict caustic crossing parameters, and a fast and efficient response of a 8 m class telescope to a "Target-of-Opportunity" observation request},
  language  = {en}
}
@article{JiangDePoyGalYametal.2004,
  author    = {Jiang, G. F. and DePoy, D. L. and Gal-Yam, A. and Gaudi, B. S. and Gould, A. and Han, C. and Lipkin, Y. and Maoz, D. and Ofek, E. O. and Park, B. G. and Pogge, R. W. and Udalski, A. and Kubiak, Marcin and Szymanski, M. K. and Szewczyk, O. and Zerbrun, K. and Wyrzykowski, L. and Soszynski, I. and Pietrzynski, G. and Albrow, Michael D. and Beaulieu, Jean-Philippe and Caldwell, John A. R. and Cassan, A. and Coutures, C. and Dominik, M. and Donatowicz, J. and Fouque, P. and Greenhill, John and Hill, K. and Horne, Keith and Jorgensen, S. F. and Jorgensen, Uffe Grae and Kane, Stephen R. and Kubas, Daniel and Martin, Ralph and Menzies, J. W. and Pollard, R. and Sahu, K. C. and Wambsganss, Joachim and Watson, R. and Williams, A.},
  title     = {OGLE-2003-BLG-238 : Microlensing mass estimate of an isolated star},
  issn      = {0004-637X},
  year      = {2004},
  abstract  = {Microlensing is the only known direct method to measure the masses of stars that lack visible companions. In terms of microlensing observables, the mass is given by M (c(2)/4G)(r) over tilde (E)theta(E) and so requires the measurement of both the angular Einstein radius theta(E) and the projected Einstein radius (r) over tilde (E). Simultaneous measurement of these two parameters is extremely rare. Here we analyze OGLE-2003-BLG-238, a spectacularly bright (I-min 10.3), high-magnification (A(max) 170) microlensing event. Pronounced finite-source effects permit a measurement of theta(E) = 650 muas. Although the timescale of the event is only t(E) 38 days, one can still obtain weak constraints on the microlens parallax: 4.4 AU < <(r)over tilde>(E) < 18 AU at the 1 \&sigma; level. Together these two parameter measurements yield a range for the lens mass of 0.36 M-\&ODOT; < M < 1.48 M-\&ODOT;. As was the case for MACHO- LMC-5, the only other single star (apart from the Sun) whose mass has been determined from its gravitational effects, this estimate is rather crude. It does, however, demonstrate the viability of the technique. We also discuss future prospects for single-lens mass measurements},
  language  = {en}
}
@article{KubasCassanBeaulieuetal.2005,
  author    = {Kubas, Daniel and Cassan, A. and Beaulieu, Jean-Philippe and Coutures, C. and Dominik, M. and Albrow, Michael D. and Brillant, Stephane and Caldwell, John A. R. and Dominis, Dijana and Donatowicz, J. and Fendt, Christian and Fouque, P. and Jorgensen, Uffe Grae and Greenhill, John and Hill, K. and Heinm{\"u}ller, Janine and Horne, Keith and Kane, Stephen R. and Marquette, Jean-Baptiste and Martin, Ralph and Menzies, J. W. and Pollard, K. R. and Sahu, K. C. and Vinter, C. and Wambsganss, Joachim and Watson, R. and Williams, A. and Thurl, C.},
  title     = {Full characterization of binary-lens event OGLE-2002-BLG-069 from PLANET observations},
  issn      = {0004-6361},
  year      = {2005},
  abstract  = {We analyze the photometric data obtained by PLANET and OGLE on the caustic-crossing binary-lens microlensing event OGLE-2002-BLG-069. Thanks to the excellent photometric and spectroscopic coverage of the event, we are able to constrain the lens model up to the known ambiguity between close and wide binary lenses. The detection of annual parallax in combination with measurements of extended-source effects allows us to determine the mass, distance and velocity of the lens components for the competing models. While the model involving a close binary lens leads to a Bulge- Disc lens scenario with a lens mass of M = (0.51 ± 0.15) M-\&ODOT; and distance of D-L = (2.9 ± 0.4) kpc, the wide binary lens solution requires a rather implausible binary black-hole lens ( M \&GSIM; 126 M-\&ODOT;). Furthermore we compare current state-of-the-art numerical and empirical models for the surface brightness profile of the source, a G5III Bulge giant. We find that a linear limb-darkening model for the atmosphere of the source star is consistent with the data whereas a PHOENIX atmosphere model assuming LTE and with no free parameter does not match our observations},
  language  = {en}
}
@article{BeaulieuBennettFouqueetal.2006,
  author    = {Beaulieu, Jean-Philippe and Bennett, David P. and Fouqu{\´e}, Pascal and Williams, Andrew and Dominik, Martin and Jorgensen, Uffe Grae and Kubas, Daniel and Cassan, Arnaud and Coutures, Christian and Greenhill, John and Hill, Kym and Menzies, John and Sackett, Penny D. and Albrow, Michael D. and Brillant, Stephane and Caldwell, John A. R. and Calitz, Johannes Jacobus and Cook, Kem H. and Corrales Cosmeli, Esperanza de Santa Cecilia and Desort, Morgan and Dieters, Stefan and Dominis, Dijana and Donatowicz, Jadzia and Hoffman, Martie and Kane, Stephen R. and Marquette, Jean-Baptiste and Martin, Ralph and Meintjes, Pieter and Pollard, Karen R. and Sahu, Kailash C. and Vinter, Christian and Wambsganss, Joachim and Woller, Kristian and Horne, Keith and Steele, Iain and Bramich, Daniel M. and Burgdorf, Martin and Snodgrass, Colin and Bode, Mike and Udalski, Andr},
  title     = {Discovery of a cool planet of 5.5 Earth masses through gravitational microlensing},
  issn      = {0028-0836},
  doi       = {10.1038/Nature04441},
  year      = {2006},
  abstract  = {In the favoured core-accretion model of formation of planetary systems, solid planetesimals accumulate to build up planetary cores, which then accrete nebular gas if they are sufficiently massive. Around M-dwarf stars ( the most common stars in our Galaxy), this model favours the formation of Earth-mass (M+) to Neptune-mass planets with orbital radii of 1 to 10 astronomical units (AU), which is consistent with the small number of gas giant planets known to orbit M-dwarf host stars(1-4). More than 170 extrasolar planets have been discovered with a wide range of masses and orbital periods, but planets of Neptune's mass or less have not hitherto been detected at separations of more than 0.15 AU from normal stars. Here we report the discovery of a 5.5(-2.7)(+5.5)M(+) planetary companion at a separation of 2.6(- 0.6)(+1.5) AU from a 0.22(-0.11)(+0.21)M(.) M-dwarf star, where M-. refers to a solar mass. (We propose to name it OGLE- 2005-BLG-390Lb, indicating a planetary mass companion to the lens star of the microlensing event.) The mass is lower than that of GJ876d (ref. 5), although the error bars overlap. Our detection suggests that such cool, sub-Neptune-mass planets may be more common than gas giant planets, as predicted by the core accretion theory.},
  language  = {en}
}