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Centro de Astrofísica da Universidade do Porto
Old Open Clusters in the Solar Neighbourhood

Stefan Schmeja
Zentrum für Astronomie der Universität Heidelberg

Abstract
There is a striking lack of old (t > 1 Gyr) open clusters in the solar neighbourhood (d < 1 kpc). Old open clusters show a larger scale height, so in combination with their small distance they may also lie at higher Galactic latitudes, whereas most systematic open cluster searches have been restricted to areas around the Galactic plane, and having a large angular extent, they do not stand out prominently as overdensities from the field. These are probably the reasons why those clusters have escaped detection so far. Our systematic search for stellar density enhancements using a star count algorithm on the 2MASS point source catalogue at Galactic latitudes |b| > 20° resulted in the discovery of 137 new open clusters with ages between 0.2 and 5 Gyr and distances < 3 kpc. Nevertheless, the volume < 1 kpc is still expected to contain about 60 unknown old clusters that probably have escaped our search.

8 May 2014, 13:30

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Institute of Astrophysics and Space Sciences

Institute of Astrophysics and Space Sciences (IA) is a new but long anticipated research infrastructure with a national dimension. It embodies a bold but feasible vision for the development of Astronomy, Astrophysics and Space Sciences in Portugal, taking full advantage and fully realizing the potential created by the national membership of the European Space Agency (ESA) and the European Southern Observatory (ESO). IA resulted from the merging the two most prominent research units in the field in Portugal: the Centre for Astrophysics of the University of Porto (CAUP) and the Center for Astronomy and Astrophysics of the University of Lisbon (CAAUL). It currently hosts more than two-thirds of all active researchers working in Space Sciences in Portugal, and is responsible for an even greater fraction of the national productivity in international ISI journals in the area of Space Sciences. This is the scientific area with the highest relative impact factor (1.65 times above the international average) and the field with the highest average number of citations per article for Portugal.

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