OGLE-2013-BLG-0723: The Circum Brown Dwarf Orbiting Venus Might be a False Positive

A New Non-Planetary Interpretation of the Microlensing Event OGLE-2013-BLG-0723

Authors:

Han et al

Abstract:

Recently, the discovery of a Venus-mass planet orbiting a brown-dwarf host in a binary system was reported from the analysis of the microlensing event OGLE-2013-BLG-0723. We reanalyze the event considering the possibility of other interpretations. From this, we find a new solution where the lens is composed of 2 bodies in contrast to the 3-body solution of the previous analysis. The new solution better explains the observed light curve than the previous solution with Δχ2∼202, suggesting that the new solution is a correct model for the event. From the estimation of the physical parameters based on the new interpretation, we find that the lens system is composed of two low-mass stars with ∼0.2 M⊙ and ∼0.1 M⊙ and located at a distance ∼3 kpc. The fact that the physical parameters correspond to those of the most common lens population located at a distance with a large lensing probability further supports the likelihood of the new interpretation. Considering that two dramatically different solutions can approximately explain the observed light curve, the event suggests the need of carefully testing all possible lens-system geometries.

OGLE-2013-BLG-0723LB/Bb: A Brown Dwarf With a Venus-Mass Exoplanet in Orbit

A Venus-Mass Planet Orbiting a Brown Dwarf: Missing Link between Planets and Moons

Authors:

Udalski et al

Abstract:

The co-planarity of solar-system planets led Kant to suggest that they formed from an accretion disk, and the discovery of hundreds of such disks around young stars as well as hundreds of co-planar planetary systems by the {\it Kepler} satellite demonstrate that this formation mechanism is extremely widespread. Many moons in the solar system, such as the Galilean moons of Jupiter, also formed out of the accretion disks that coalesced into the giant planets. We report here the discovery of an intermediate system OGLE-2013-BLG-0723LB/Bb composed of a Venus-mass planet orbiting a brown dwarf, which may be viewed either as a scaled down version of a planet plus star or as a scaled up version of a moon plus planet orbiting a star. The latter analogy can be further extended since they orbit in the potential of a larger, stellar body. For ice-rock companions formed in the outer parts of accretion disks, like Uranus and Callisto, the scaled masses and separations of the three types of systems are similar, leading us to suggest that formation processes of companions within accretion disks around stars, brown dwarfs, and planets are similar.