Polar surges and macrospicules : simultaneous H α and He II 304 Å observations

We compare simultaneous sequences of Hα and He ii 304Å images near the solar limb. We propose to distinguish polar surges and giant spicules (macrospicules), among the He ii structures observed beyond the solar limb. Polar surges have a complex structure when observed in Hα and an erup-tive nature, reminiscent of normal surges in small scale. Giant spicules are simple spikes, very narrow compared to surges. They don't go as high as polar surges and apparently have shorter lifetimes. We found that most polar surges and giant spicules observed in He ii are associated with Hα spikes; however there were cases without any corresponding Hα structure. Furthermore we observed Hα spikes that did not have He ii counterparts. We analyze an example of a polar surge that appeared in He ii well before its appearance in Hα and remained visible for a longer time. Most polar surges that we observed showed a similar behavior.