Sunday, May 22, 2016

A Giant Planet in the Light Curve

Figure 1: Artist's impression of a giant planet.

Gould et al. (2016) present the discovery of a massive planet with 4.4 ± 1.6 times the mass of Jupiter in orbit around a red dwarf star with 0.37 ± 0.14 times the mass of the Sun. This system was discovered via gravitational microlensing, whereby the planet-star system crosses the line-of-sight to a background star and the gravitational field of the planet-star system acts as a lens, magnifying light from the background star. The projected separation between the planet and star is estimated to be ~1.2 AU.

This gravitational microlensing event is identified as OGLE-2015-BLG-0954 and it was observed by the Korea Microlensing Telescope Network (KMTNet), a system of three 1.6 m telescopes located in Chile, South Africa and Australia. The wide field of view and the high cadence (6 measurements per hour) of KMTNet allowed for this gravitational microlensing event to be measured despite the short line-of-sight crossing time of only 16 minutes.

Figure 2: Light curve and best-fit model for KMTNet observations of OGLE-2015-BLG-0954 with data from Chile (red), South Africa (blue) and Australia (magenta). Insets show the caustic which extends from 7164.62 to 7165.15. Error bars are omitted from the main figure to avoid clutter but are shown in the residuals. Gould et al. (2016)

Gould et al. (2016), "A Super-Jupiter Microlens Planet Characterized by High-Cadence KMTNet Microlensing Survey Observations", arXiv:1603.00020 [astro-ph.EP]