Alan Prestes

Interplanetary shock parameters during solar activity maximum (2000) and minimum (1995-1996)

Interplanetary shock parameters are analyzed for solar maximum (year 2000) and solar minimum (years 1995-1996) activity. Fast forward shocks are the most usual type of shock observed in the interplanetary medium near Earths orbit, and they are 88% of the identified shocks in 2000 and 60% in 1995-1996. Average plasma and magnetic field parameters for upstream and downstream sides of the shocks were calculated, and the parameter variations through the shock were determined. Applications of the Rankine-Hugoniot equations were made, obtaining shock speeds and Alfvenic Mach number. Static and dynamic pressures variations through the shocks were also calculated. Every parameter have larger variation through the shock in solar maximum than in solar minimum, with exception of the proton density. The intensity of shocks relative to the interplanetary medium, quantified by the Alfvenic Mach Number, is observed to be similar in solar maximum and minimum. It could be explained because, during solar maximum, in despite of the higher shock speeds, the Alfvenic speed of the interplanetary medium is higher than in solar minimum.

Sunspot number, solar activity index

On ´ umero de manchas solares ´ondice mais antigo da atividade solar, com observac ¸˜ oes de manchas solares estendendo-se desde 1611. Ele serve como uma medida da atividade magnetica geral do Sol. Neste trabalho apresentamos uma descric ¸˜ ao das caracter´osticas f´ osicas das manchas solares, a definic ¸˜ ao do numero de manchas solares, uma analise espectral do mesmo e uma reconstruc ¸˜ ao de 1000 anos. The sunspot number is the longest solar activity index available with observations since 1611. It is a measure of the general state of solar magnetic activity. In this work we present a desciption of sunspot physical caracte- ristics, the definition of the sunspot number, a spectral analysis and a reconstruction for the last 1000 years of the sunspot number.