ar X iv : a st ro - p h / 99 05 23 3 v 1 1 8 M ay 1 99 9 Three very young HgMn stars in the Orion OB 1 Association

ar X iv : a st ro - p h / 98 05 18 9 v 1 1 4 M ay 1 99 8 Isotopic composition of Hg and Pt in slowly rotating HgMn stars

Preliminary results from a study of the isotopic compositions of the elements Hg and Pt in a number of HgMn stars are presented. This work represents an improvement over previous studies thanks to the very high spectral resolution available (R = 118 000) and to the new information on wavelengths and atomic structure of Hg II and Pt II.

ar X iv : a st ro - p h / 98 05 06 4 v 1 6 M ay 1 99 8 Mercury and platinum abundances in mercury - manganese stars

We report new results for the elemental and isotopic abundances of the normally rare elements mercury and platinum in HgMn stars. Typical overabundances can be 4 dex or more. The isotopic patterns do not follow the fractionation model of White et al (1976).

ar X iv : a st ro - p h / 98 05 23 3 v 1 1 8 M ay 1 99 8 HgMn Stars as apparent X - ray emitters

In the ROSAT all-sky survey 11 HgMn stars were detected as soft X-ray emitters (Berghöfer, Schmitt & Cassinelli 1996). Prior to ROSAT, X-ray observations with the Einstein Observatory had suggested that stars in the spectral range B5–A7 are devoid of X-ray emission. Since there is no X-ray emitting mechanism available for these stars (also not for HgMn stars), the usual argument in the case of ...

ar X iv : a st ro - p h / 98 05 24 3 v 1 1 9 M ay 1 99 8 ι Cas : Multi - element Doppler imaging and magnetic field geometry

In order to clarify the role of the magnetic field in generating abundance inhomogeneities in the atmospheres of Ap stars, we present new abundance Doppler images and an approximate magnetic field geometry for the Ap star ι Cas.

ar X iv : a st ro - p h / 99 05 37 6 v 1 2 8 M ay 1 99 9 A 6 . 4 - hr positive superhump period in TV