Mercury-manganese star

Closely related to the Ap stars are the mercury -manganese star or HgMn stars. Both classes of stars are among the chemical- Pekuliären stars, the CP stars. The HgMn star show strong over frequencies of P, Mn, Ga, Br, Sr, Y, Zr, Rh, Pd, Xe, Pr, Yb, W, Re, Os, Pt, Au, and Hg, and marked lower frequencies of He, Al, Zn, Ni, and Co. the spectral type of the HgMn star is a late example, some elements show widely differing isotopic ratios, but they are very individual for each star. The mercury -manganese stars rotate very slowly for their early spectral class with an average corrected for the inclination speed of 30 kilometers per second. The frequency of HgMn -star with increasing rotation speed drops off sharply. More than two-thirds of all the stars of this class of stars are among the spectroscopic binaries with orbital periods between three and twenty days. Even with the mercury -manganese stars, the elements are not evenly distributed, the mercury being present probably concentrated at the equator. Other elements such as Ti, Cr, Fe, Mn, Sr, Y, and Pt are, however, rather than spots as in the Ap stars before somewhere on the hemisphere of the star. This is most often associated with a magnetic field on the surface of the star. The contrast, mercury -manganese stars have very weak magnetic fields with flux densities exceeding a few tens of Gauss ( = a few milli Tesla), while the magnetic flux density in the Ap stars reaches a few thousand gauss.

Representative

The following table shows the brightest representatives of this class of stars: