Another OGLE-2005-BLG-169b Confirmation Through Keck

CONFIRMATION OF THE OGLE-2005-BLG-169 PLANET SIGNATURE AND ITS CHARACTERISTICS WITH LENS–SOURCE PROPER MOTION DETECTION

Authors:

Batista et al

Abstract:

We present Keck NIRC2 high angular resolution adaptive optics observations of the microlensing event OGLE-2005-BLG-169Lb, taken 8.21 years after the discovery of this planetary system. For the first time for a microlensing planetary event, the source and the lens are completely resolved, providing a precise measurement of their heliocentric relative proper motion, ${\mu }_{\mathrm{rel},\mathrm{helio}}=7.44\pm 0.17$ mas yr−1. This confirms and refines the initial model presented in the discovery paper and rules out a range of solutions that were allowed by the microlensing light curve. This is also the first time that parameters derived from a microlensing planetary signal are confirmed, both with the Keck measurements, presented in this paper, and independent measurements obtained with the Hubble Space Telescope in $I,V$ and B bands, presented in a companion paper. Hence, this new measurement of ${\mu }_{\mathrm{rel},\mathrm{helio}}$, as well as the measured brightness of the lens in H band, enabled the mass and distance of the system to be updated: a Uranus-mass planet (${m}_{{\rm{p}}}=13.2\pm 1.3{M}_{\oplus }$) orbiting a K5-type main sequence star (${M}_{*}=0.65\pm 0.05{M}_{\odot }$) separated by ${a}_{\perp }=3.4\pm 0.3$ AU, at the distance ${D}_{{\rm{L}}}=4.0\pm 0.4$ kpc from us.

OGLE-2005-BLG-169b: a Neptune Class Exoplanet Orbiting at 4 AU

CONFIRMATION OF THE PLANETARY MICROLENSING SIGNAL AND STAR AND PLANET MASS DETERMINATIONS FOR EVENT OGLE-2005-BLG-169

Authors:

Bennett et al

Abstract:

We present Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) observations of the source and lens stars for planetary microlensing event OGLE-2005-BLG-169, which confirm the relative proper motion prediction due to the planetary light curve signal observed for this event. This (and the companion Keck result) provide the first confirmation of a planetary microlensing signal, for which the deviation was only 2%. The follow-up observations determine the flux of the planetary host star in multiple passbands and remove light curve model ambiguity caused by sparse sampling of part of the light curve. This leads to a precise determination of the properties of the OGLE-2005-BLG-169Lb planetary system. Combining the constraints from the microlensing light curve with the photometry and astrometry of the HST/WFC3 data, we find star and planet masses of M*=0.69 solar mass +/- 0.02 solar mass and mp=14.1 earth mass +/- 0.9 earth mass. The planetary microlens system is located toward the Galactic bulge at a distance of DL=4.1 kpc +/- 0.4 kpc and the projected star–planet separation is a =3.5 AU +/- 0.3 AU, corresponding to a semimajor axis of a=4.0 AU +2.2/-.6 AU.