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Centro de Astrofísica da Universidade do Porto

The discontinuous nature of chromospheric-activity evolution

G. Pace

Chromospheric activity has been thought to decay smoothly with time and, hence, to be a viable age indicator. Measurements in solar-type stars in open clusters seem to point to a different conclusion: chromospheric activity undergoes a fast transition from Hyades level to that of the Sun after about 1 Gyr of main-sequence lifetime and any decaying trend before or after this transition must be much less significant than the short-term variations.

Chromospheric activity - Stars in open clusters - Stellar ages

Astrophysics and Space Science
Volume 328, Page 307
July 2010

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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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