TY - JOUR
A1 - Sackett, Penny D.
A1 - Albrow, Michael D.
A1 - Beaulieu, J. P.
A1 - Caldwell, John A. R.
A1 - Coutures, C.
A1 - Dominik, M.
A1 - Greenhill, John
A1 - Hill, K.
A1 - Horne, Keith
A1 - Jorgensen, Uffe Grae
A1 - Kane, Stephen R.
A1 - Kubas, Daniel
A1 - Martin, Ralph
A1 - Menzies, J. W.
A1 - Pollard, K. R.
A1 - Sahu, K. C.
A1 - Wambsganß, Joachim
A1 - Watson, R.
A1 - Williams, A.
T1 - PLANET II : a microlensing and transit search for extrasolar planets
N2 - 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.
Y1 - 2003
UR - http://arxiv.org/pdf/astro-ph/0211098
ER -
TY - JOUR
A1 - Cassan, A.
A1 - Beaulieu, J. P.
A1 - Brillant, S.
A1 - Coutures, C.
A1 - Dominik, M.
A1 - Donatowicz, J.
A1 - Jorgensen, Uffe Grae
A1 - Kubas, Daniel
A1 - Albrow, Michael D.
A1 - Caldwell, John A. R.
A1 - Fouque, P.
A1 - Greenhill, John
A1 - Hill, K.
A1 - Horne, Keith
A1 - Kane, Stephen R.
A1 - Martin, Ralph
A1 - Menzies, J. W.
A1 - Pollard, K. R.
A1 - Sahu, K. C.
A1 - Vinter, C.
A1 - Wambsganss, Joachim
A1 - Watson, R.
A1 - Williams, A.
A1 - Fendt, Christian
A1 - Hauschildt, P.
A1 - Heinmueller, Janine
A1 - Marquette, Jean-Baptiste
A1 - Thurl, C.
T1 - Probing the atmosphere of the bulge G5III star OGLE-2002-BUL-069 by analysis of microlensed H alpha line
N2 - 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
Y1 - 2004
ER -
TY - JOUR
A1 - Kubas, Daniel
A1 - Cassan, A.
A1 - Beaulieu, J. P.
A1 - Coutures, C.
A1 - Dominik, M.
A1 - Albrow, Michael D.
A1 - Brillant, S.
A1 - Caldwell, John A. R.
A1 - Dominis, Dijana
A1 - Donatowicz, J.
A1 - Fendt, Christian
A1 - Fouque, P.
A1 - Jorgensen, Uffe Grae
A1 - Greenhill, John
A1 - Hill, K.
A1 - Heinmüller, Janine
A1 - Horne, Keith
A1 - Kane, Stephen R.
A1 - Marquette, Jean-Baptiste
A1 - Martin, Ralph
A1 - Menzies, J. W.
A1 - Pollard, K. R.
A1 - Sahu, K. C.
A1 - Vinter, C.
A1 - Wambsganss, Joachim
A1 - Watson, R.
A1 - Williams, A.
A1 - Thurl, C.
T1 - Full characterization of binary-lens event OGLE-2002-BLG-069 from PLANET observations
N2 - 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
Y1 - 2005
SN - 0004-6361
ER -
TY - JOUR
A1 - Jiang, G. F.
A1 - DePoy, D. L.
A1 - Gal-Yam, A.
A1 - Gaudi, B. S.
A1 - Gould, A.
A1 - Han, C.
A1 - Lipkin, Y.
A1 - Maoz, D.
A1 - Ofek, E. O.
A1 - Park, B. G.
A1 - Pogge, R. W.
A1 - Udalski, A.
A1 - Kubiak, Marcin
A1 - Szymanski, M. K.
A1 - Szewczyk, O.
A1 - Zerbrun, K.
A1 - Wyrzykowski, L.
A1 - Soszynski, I.
A1 - Pietrzynski, G.
A1 - Albrow, Michael D.
A1 - Beaulieu, J. P.
A1 - Caldwell, John A. R.
A1 - Cassan, A.
A1 - Coutures, C.
A1 - Dominik, M.
A1 - Donatowicz, J.
A1 - Fouque, P.
A1 - Greenhill, John
A1 - Hill, K.
A1 - Horne, Keith
A1 - Jorgensen, S. F.
A1 - Jorgensen, Uffe Grae
A1 - Kane, Stephen R.
A1 - Kubas, Daniel
A1 - Martin, Ralph
A1 - Menzies, J. W.
A1 - Pollard, R.
A1 - Sahu, K. C.
A1 - Wambsganss, Joachim
A1 - Watson, R.
A1 - Williams, A.
T1 - OGLE-2003-BLG-238 : Microlensing mass estimate of an isolated star
N2 - 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 σ 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
Y1 - 2004
SN - 0004-637X
ER -