We analyze long-term variations of several solar activity indices(AIs) that have been measured over the last 40 years.With this goal,we study the AIs that characterize the fluxes from different areas in the solar atmo...We analyze long-term variations of several solar activity indices(AIs) that have been measured over the last 40 years.With this goal,we study the AIs that characterize the fluxes from different areas in the solar atmosphere.Our consideration of mutual correlations between the solar indices is based on the study of relationships between them in the period from 1950 to 1990.This period of time,covering activity cycles 19–22,is characterized by relatively stable relations between the indices.We investigate the normalized variations of these indices in recent time in relation to their values which were calculated by considering radiation from the Sun in the radio range at a wavelength of 10.7 cm(F10.7) in 1950–1990.The analysis of time series,representing variations of the normalized AI(AIFF) in solar cycles 23–24,shows different trends exist for different indices in terms of their long-term behavior.We assume that variations of normalized International Sunspot Number(SSN),F530.3 and Flare Index,which have shown sharp decreases in the last 40 years,are possibly associated with a decrease in the intensity of large-scale magnetic fields in the photosphere(SSN) and in the corona(the coronal index and the Flare Index).展开更多
The atmospheric activity of the Sun and Sun-like stars is analyzed involving observations from the HK-project at the Mount Wilson Observatory, the California and Carnegie Planet Search Program at the Keck and Lick Obs...The atmospheric activity of the Sun and Sun-like stars is analyzed involving observations from the HK-project at the Mount Wilson Observatory, the California and Carnegie Planet Search Program at the Keck and Lick Observatories and the Magellan Planet Search Program at the Las Campanas Observatory. We show that for stars of E G and K spectral classes, the cyclic activity, similar to the 11-yr solar cycle, is different： it becomes more prominent in K-stars. Comparative study of Sun-like stars with different levels of chromospheric and coronal activity confirms that the Sun belongs to stars with a low level of chromospheric activity and stands apart among these stars by its minimum level of coronal radiation and minimum level of variations in photospheric flux.展开更多
文摘We analyze long-term variations of several solar activity indices(AIs) that have been measured over the last 40 years.With this goal,we study the AIs that characterize the fluxes from different areas in the solar atmosphere.Our consideration of mutual correlations between the solar indices is based on the study of relationships between them in the period from 1950 to 1990.This period of time,covering activity cycles 19–22,is characterized by relatively stable relations between the indices.We investigate the normalized variations of these indices in recent time in relation to their values which were calculated by considering radiation from the Sun in the radio range at a wavelength of 10.7 cm(F10.7) in 1950–1990.The analysis of time series,representing variations of the normalized AI(AIFF) in solar cycles 23–24,shows different trends exist for different indices in terms of their long-term behavior.We assume that variations of normalized International Sunspot Number(SSN),F530.3 and Flare Index,which have shown sharp decreases in the last 40 years,are possibly associated with a decrease in the intensity of large-scale magnetic fields in the photosphere(SSN) and in the corona(the coronal index and the Flare Index).
文摘The atmospheric activity of the Sun and Sun-like stars is analyzed involving observations from the HK-project at the Mount Wilson Observatory, the California and Carnegie Planet Search Program at the Keck and Lick Observatories and the Magellan Planet Search Program at the Las Campanas Observatory. We show that for stars of E G and K spectral classes, the cyclic activity, similar to the 11-yr solar cycle, is different： it becomes more prominent in K-stars. Comparative study of Sun-like stars with different levels of chromospheric and coronal activity confirms that the Sun belongs to stars with a low level of chromospheric activity and stands apart among these stars by its minimum level of coronal radiation and minimum level of variations in photospheric flux.
