Van den Heuvel and Tauris argue that if the red giant star in the system 2MASS J05215658+4359220 has a mass of 1 solar mass (M ☉), then its unseen companion could be a binary composed of two 0.9 M ☉ stars, making a triple system. We contend that the existing data are most consistent with a giant of mass [Formula: see text] M ☉, implying a black hole companion of [Formula: see text] M ☉.
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