Work

A Newly Identified Degeneracy Keeps the Planetary Interpretation Viable for OGLE-2011-BLG-0950

Year: 2026

Type: article

Abstract: The microlensing event OGLE-2011-BLG-0950 exhibits the well-known “Planet/Binary” degeneracy, in which distinct lens configurations produce similar light curves but imply substantially different mass ratios between the lens components. A previous study rejected the then-known planetary model because its predicted lens-source relative proper motion was inconsistent with that measured from high-resolution imaging, thereby favoring the stellar-binary interpretation. In this work, we identify a new planetary model for this event that arises from a newly identified degeneracy, simultaneously reproducing the observed light curve and remaining consistent with the high-resolution imaging constraint, leaving the “Planet/Binary” degeneracy unresolved once again. Under this planetary interpretation, combining constraints from the light-curve modeling and high-resolution observations yields a lens system consisting of a ∼1 M ⊙ host star orbited by a ∼1.5 M Jup planet, with a projected separation of about 2 or 8 au, subject to the “Close/Wide” degeneracy. Our reanalysis of the color–magnitude diagram further indicates that the source star has unresolved companions that contribute nonnegligible blended light, highlighting the importance of carefully accounting for source and lens companions in future Roman microlensing analyses. Finally, we show that adopting a single mass–luminosity relation significantly underestimates the uncertainties in the inferred lens properties for host masses ≳1 M ⊙ .

Source: The Astronomical Journal

DOI: 10.3847/1538-3881/aea291