New developments on the field of chemically peculiar stars in the milky way and the LMC

During the IAU Symposium No. 224 (July 2004) we, the Vienna ?a Research Group, have presented our ongoing research projects. Important contributions have been attained since: In collaboration with I.Kh. Iliev (Rozhen, Bulgaria), O.I. Pintado (Tucuman, Argentina) and A. Claret (Granada, Spain) six galactic open clusters were surveyed for the presence of chemically peculiar (CP) stars using the photometric ?a index. This brings the record of our photometric survey (both photoelectric and CCD) to 65 published clusters. The aim of this survey is to identify conditions which favour the existence of peculiar stars (especially those with strong global magnetic fields), and complementary those which inhibit their formation in open clusters. In the present paper, with NGC 3105 so far the most distant cluster (8.5 kpc from the Sun) in our Galaxy was observed this way and the detection of one CP star was reported. Again with Pintado and Claret, the ?a search for peculiar stars was continued in the Large Magellanic Cloud (LMC) in two fields: one centered on the open cluster NGC 1711 and one on the typical bulge population. Although the frequency of CP stars is slightly higher than in the region of the LMC cluster NGC 1866 as found in Maitzen et al. (2001, A&A, 371, L5), it is significantly lower by approximately 50% than in our Galaxy. After the initialising paper by Pošhnl et al. (2003, A&A, 402, 247) on the evolutionary status of magnetic CP stars in open clusters, the appearance of these stars in the solar neighbourhood (up to 200 pc) has been investigated in an analogous way. We are able to show that the phenomenon of magnetic fields present in upper main sequence CP stars occurs continuously already from the zero age main sequence between 1.5 and 4.5 solar masses. We report further activities concerning the modelling of the 5200A°-region, especially for hot CP stars, the behaviour of B-type stars in the ?a system, the search for CP2 analogues on the blue horizontal branch of globular clusters and the finalisation of photoelectric photometry in open cluster using ?a photometry.