HD66051, an eclipsing binary hosting a highly peculiar, HgMn-related star

摘要

HD66051 is an eclipsing system with an orbital period of about 4.75 d thatexhibits out-of-eclipse variability with the same period. New multicolourphotometric observations confirm the longevity of the secondary variations,which we interpret as a signature of surface inhomogeneities on one of thecomponents. Using archival and newly acquired high-resolution spectra, we haveperformed a detailed abundance analysis. The primary component is a slowlyrotating late B-type star ($T_{\rm eff} = 12500\pm200$ K; $\log g = 4.0$,$v\sin i = 27\pm2$ km s$^{-1}$) with a highly peculiar composition reminiscentof the singular HgMn-related star HD 65949, which seems to be its closestanalogue. Some light elements as He, C, Mg, Al are depleted, while Si and P areenhanced. Except for Ni, all the iron-group elements, as well as most of theheavy elements, and in particular the REE elements, are overabundant. Thesecondary component was estimated to be a slowly rotating A-type star ($T_{\rmeff} \sim 8000$ K; $\log g = 4.0$, $v\sin i \sim 18$ km s$^{-1}$). The uniqueconfiguration of HD\,66051 opens up intriguing possibilities for futureresearch, which might eventually and significantly contribute to theunderstanding of such diverse phenomena as atmospheric structure, masstransfer, magnetic fields, photometric variability and the origin of chemicalanomalies observed in HgMn stars and related objects.