HD 66051, an eclipsing binary hosting a highly peculiar, HgMn-related star

Astronomers have long studied binary star systems to understand stellar evolution and chemical anomalies. While many eclipsing binaries show predictable behavior, some display unusual photometric variations. These deviations suggest surface inhomogeneities or other physical processes. Prior research has identified HgMn stars as chemically peculiar objects with distinct abundance patterns. However, the mechanisms behind these anomalies remain unclear. Few systems combine eclipsing behavior with HgMn-like characteristics. This gap motivated further investigation into systems like HD 66051. The need exists to link photometric variability with chemical composition in such binaries. No prior work had resolved the full spectral and photometric profile of this system.

This study aimed to analyze the eclipsing binary HD 66051 to determine its physical properties and chemical composition. The system exhibits out-of-eclipse variability, suggesting surface features or chemical peculiarities. The researchers sought to confirm the nature of these variations using photometric and spectroscopic data. They focused on identifying the components' temperatures, rotation speeds, and elemental abundances. The goal was to compare the primary star with known HgMn-related stars like HD 65949. The study also aimed to assess the secondary component's characteristics. The motivation was to explore how such systems contribute to broader astrophysical questions. The results could help explain the origin of chemical anomalies in HgMn stars.

The researchers combined multicolour photometric observations with high-resolution spectroscopic data. They analyzed archival and newly acquired spectra to determine the system's orbital and physical parameters. The photometric data confirmed the persistence of out-of-eclipse variability. Spectral analysis focused on determining effective temperatures, surface gravities, and rotational velocities. Abundance analysis was conducted for various elements, including light and heavy metals. The primary star's spectrum showed depletion of He, C, Mg, and Al. In contrast, Si and P were enriched. The secondary star's parameters were estimated using similar methods.

The primary component is a late B-type star with a temperature of 12500 ± 200 K and a rotational velocity of 27 ± 2 km s^-1. Its chemical composition resembles that of HD 65949, a known HgMn-related star. Light elements like He, C, Mg, and Al are depleted in the primary star. In contrast, Si and P are enriched. Iron-group elements and rare earth elements are overabundant. The secondary star is a slowly rotating A-type star with a temperature of ~8000 K. Its rotational velocity is ~18 km s^-1. The system's unique configuration suggests ongoing processes like mass transfer or magnetic activity.

The study confirms that HD 66051 is an eclipsing binary with a primary star displaying HgMn-related chemical peculiarities. The primary star's composition is highly unusual, with depleted light elements and enriched Si and P. The secondary star is a slowly rotating A-type star. The system's configuration offers new insights into atmospheric structure and chemical anomalies. The findings suggest that HD 66051 is a valuable system for future research. The authors propose that this system could help clarify the role of magnetic fields and mass transfer in HgMn stars. The results highlight the importance of combining photometric and spectroscopic data. The system's unique properties may lead to broader understanding of chemical anomalies in binaries.