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Chemically peculiar stars
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Extragalactic CP stars
The first extragalactic classical chemically peculiar stars more than 100 years after
the discovery of this group were detected (Maitzen et al. 2001).
Using the tool of CCD
a-photometry, eight definite positive detections in the globular-like stellar cluster
NGC 1866 and its surrounding in the Large Magellanic Cloud were made (Figure).
More than 1950 objects down to 20.5 mag were observed. Furthermore we found three objects with
significantly negative
a-values indicating either an Ae/shell or lBootis nature.
The overall percentage of chemically peculiar stars for NGC 1866 (1.5 %) seems lower
than for the majority of open clusters in our Milky Way whereas the incidence within
the LMC field is decisively less (0.3 %).
Article in the University newspaper (in German)
To corroborate the result of a search for chemically peculiar stars in the
Large Magellanic Cloud (LMC), we present measurements obtained from CCD imaging of two
fields, one containing a young open cluster (NGC 1711). While for the latter field,
including its surrounding we obtain a contribution of 3% of chemically peculiar
stars detectable by
a photometry, the
second field yields about half of this value in good accordance with the
finding for NGC 1866. Thus, we are faced with the fact
that our incipient impression about a substantially lower appearance of magnetic
chemically peculiar stars in the LMC as compared to the Galaxy continues to be valid.
Most of the photometrically identified peculiar stars (from their historical origin
denominated Ap stars) are located in the domain of the B-type stars. However, this
is a selection effect due to the limiting magnitude of our observing conditions
impeding the observation of fainter main-sequence stars
(Paunzen et al. 2005).
Furthermore, with the help of the ESO 2.2m WFI,
observations of a 30' large field within the Small Magellanic Cloud were performed, containing several
clusters and a total of about 100.000 stars. The reduction of this enormous amount of data is still
in progress.