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Variations of UV chromospheric emissions during a pulsation period ofϱ Puppis (HD 67523)

Fracassini, M.; Pasinetti, L. E.; Castelli, F. +2 more

The peculiar δ Del-variable ϱ Puppis (F6IIp) has been analysed on nine UV high-resolution spectra in the region of MgII h- and k-lines. This analysis has shown: (1) The MgII emission is present during the whole pulsation period and increases with increasing luminosity. Maximum emission fluxes seem to occur at phases 0.96–0.12. (2) The phase shift …

Interstellar proteins and the discovery of a new absorption feature at λ=2800 Å

Wickramasinghe, N. C.; Karim, L. M.; Hoyle, F.

The discovery of a broad interstellar absorption feature centred on λ2800 Å in the extinction curve of starlight confirms the presence of proteinaceous material in grains.

The Age Decay of Stellar Magnetic Activity in MS Field Solar Type Stars

Vazquez, M.; Cabestany, J.

The age decay of two indicators of the stellar magnetic activity (λ 2800 MgII emission flux and λ 10830 HeI equivalent width) have been studied for field solar-type stars. The Li abundance has been used, in most of the cases, as a stellar age indicator. A calibrated decay law for MgII has been determined and compared with a similar one, recently p…