English

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

Earth and Planetary Astrophysics 2026-01-21 v1 Astrophysics of Galaxies Solar and Stellar Astrophysics

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 suggested that high-resolution imaging could break this degeneracy through differences in the lens-source relative proper motion. 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 relative proper motion measured from high-resolution imaging. By combining constraints from the light-curve modeling and high-resolution observations, we infer a lens system consisting of a 1 M\sim 1~M_{\odot} host star orbited by a 1.5 MJup\sim 1.5~M_{\rm 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 non-negligible 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\gtrsim 1~M_{\odot}.

Keywords

Cite

@article{arxiv.2601.13276,
  title  = {A Newly Identified Degeneracy Keeps the Planetary Interpretation Viable for OGLE-2011-BLG-0950},
  author = {Jiyuan Zhang and Weicheng Zang and Andrzej Udalski and Hongjing Yang and Shude Mao and Michał K. Szymański and Igor Soszyński and Radoslaw Poleski and Krzysztof Ulaczyk and Paweł Pietrukowicz and Szymon Kozłowski and Jan Skowron and Przemek Mróz and Sean K. Terry and Andrew Gould},
  journal= {arXiv preprint arXiv:2601.13276},
  year   = {2026}
}

Comments

submitted to AJ