HD 52721 as a Quadruple System

Abstract—We present the study of the multiple system HD 52721 by means of speckle interferometry in 2019–2020 at the 6-m telescope of the SAO RAS. Formerly, HD 52721 was known as triple ( $$6.93$$ (B2V + B2V; $$P = {{1}^{{\text{d}}}}.6101570$$ ) + $$7.88$$ ; $$0_{.}^{'}65$$ ). In our work, the system is resolved as a speckle interferometric triple system, i.e., the total system multiplicity increased up to four components ( $$6.80$$ (B2Ve; $${{1}^{{\text{d}}}}.6101570$$ )+ $$8.95$$ (B9VХ, $$0_{.}^{{''}}03$$ ); $$0_{.}^{{''}}64$$ ). We have used the reference-dependent and reference-independent methods for measuring positional parameters and magnitude differences between the components. The obtained measurements of the brightness differences agree with the observed light curve of the eclipsing pair.