First Microlens Mass Measurement: PLANET Photometry of EROS BLG‐2000‐5

An, J.; Albrow, M. D.; Beaulieu, J. P.; Caldwell, J. A. R.; DePoy, D. L.; Dominik, M.; Gaudi, B. Scott; Gould, Andrew; Greenhill, J.; Hill, K.; Kane, Stephen R.; Martín, Roland; Menzies, John; Pogge, Richard W.; Pollard, K. R.; Sackett, Penny D.; Sahu, K. C.; Vermaak, P.; Watson, R.; Williams, A.

doi:10.1086/340191

Cited by 186 publications

(117 citation statements)

References 47 publications

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“…For events with measurable microlensing parallax signals, it is possible to determine the lens system mass if the angular Einstein radius, θ E , can also be determined (Gould 1992;An et al 2002),…”

Section: Lens System Propertiesmentioning

confidence: 99%

THE FIRST CIRCUMBINARY PLANET FOUND BY MICROLENSING: OGLE-2007-BLG-349L(AB)c

Bennett¹,

Rhie²,

Udalski³

et al. 2016

Self Cite

106

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We present the analysis of the first circumbinary planet microlensing event, OGLE-2007-BLG-349. This event has a strong planetary signal that is best fit with a mass ratio of q≈3.4×10 −4 , but there is an additional signal due to an additional lens mass, either another planet or another star. We find acceptable light-curve fits with two classes of models: two-planet models (with a single host star) and circumbinary planet models. The light curve also reveals a significant microlensing parallax effect, which constrains the mass of the lens system to be M L ≈0.7  M . Hubble Space Telescope (HST) images resolve the lens and source stars from their neighbors and indicate excess flux due to the star(s) in the lens system. This is consistent with the predicted flux from the circumbinary models, where the lens mass is shared between two stars, but there is not enough flux to be consistent with the two-planet, one-star models. So, only the circumbinary models are consistent with the HST data. They indicate a planet of mass m c =80±13 Å M , orbiting a pair of M dwarfs with masses of M A =0.41±0.07 and M B =0.30±0.07, which makes this the lowest-mass circumbinary planet system known. The ratio of the separation between the planet and the center of mass to the separation of the two stars is ∼40, so unlike most of the circumbinary planets found by Kepler, the planet does not orbit near the stability limit.

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Section: Lens System Propertiesmentioning

confidence: 99%

THE FIRST CIRCUMBINARY PLANET FOUND BY MICROLENSING: OGLE-2007-BLG-349L(AB)c

Bennett¹,

Rhie²,

Udalski³

et al. 2016

Self Cite

106

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“…An et al (2002) and Fields et al (2003) constrained non-linear limb-darkening relations from microlensing observations of a K3 giant and compared them to model stellar atmospheres. They found significant disagreement between the observed and predicted limb-darkening relation.…”

Section: Introductionmentioning

confidence: 99%

Spherically-symmetric model stellar atmospheres and limb darkening

Neilson

Lester

2013

A&A

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Model stellar atmospheres are fundamental tools for understanding stellar observations from interferometry, microlensing, eclipsing binaries and planetary transits. However, the calculations also include assumptions, such as the geometry of the model. We use intensity profiles computed for both plane-parallel and spherically symmetric model atmospheres to determine fitting coefficients in the BVRIHK, CoRot and Kepler wavebands for limb darkening using several different fitting laws, for gravity-darkening and for interferometric angular diameter corrections. Comparing predicted variables for each geometry, we find that the spherically symmetric model geometry leads to different predictions for surface gravities log g < 3. In particular, the most commonly used limb-darkening laws produce poor fits to the intensity profiles of spherically symmetric model atmospheres, which indicates the need for more sophisticated laws. Angular diameter corrections for spherically symmetric models range from 0.67 to 1, compared to the much smaller range from 0.95 to 1 for plane-parallel models.

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“…Therefore, we calculate the magnifications using the inverse ray-shooting method (Kayser et al 1986;Schneider & Weiss 1986;Wambsganss 1997). In addition, we also take into account the limb-darkening effect by the surface of the source star (Milne 1921;An et al 2002). The specific intensity I is described by…”

Section: Deviation Mapmentioning

confidence: 99%

Properties and Detection Limits of Planetary Caustic Perturbation Induced by a Wide-Separation Planet

Ryu

Chung

Lee

et al. 2016

ApJ

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Microlensing experiments are entering a next generation of survey types to monitor a wide field of view continuously with a frequent sampling. The theoretically predicted sensitivity of a planet detection on the lensing parameters can be used for the establishment of observational strategies for maximal planet detections. Hence, we investigate the detection condition of planetary signals caused by the planetary caustic. We calculate the deviation area induced by the planetary caustic for various lensing parameters and find that the deviation area generally increases according to the increase of the source radius. However, after the normalized source radius approaches a certain value the deviation area rapidly decreases and disappears at the same normalized source radius, regardless of the mass ratio and the separation between the planet and its host star. We find a simple relation between the normalized source radius and the deviation threshold for the largest and smallest deviation areas. From this relation we also find an analytic condition for the detection limit of the planetary signal as the function of the source radius and the deviation threshold. In addition, we compare the deviation areas and the light curves between the planetary caustic perturbation and a free-floating planet. We find that the planetary caustic perturbation can be approximated by the single-lensing light curve of the planet itself perturbed by the planetary caustic. Finally, we can expect to find a low-mass planet with the Earth's mass or even that of the Earthʼs moon from the detection condition and conclude that our findings may help for maximal planet detections considering the source type and the photometric accuracy.

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First Microlens Mass Measurement: PLANET Photometry of EROS BLG‐2000‐5

Cited by 186 publications

References 47 publications

THE FIRST CIRCUMBINARY PLANET FOUND BY MICROLENSING: OGLE-2007-BLG-349L(AB)c

THE FIRST CIRCUMBINARY PLANET FOUND BY MICROLENSING: OGLE-2007-BLG-349L(AB)c

Spherically-symmetric model stellar atmospheres and limb darkening

Properties and Detection Limits of Planetary Caustic Perturbation Induced by a Wide-Separation Planet

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