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Observations of EUV and Soft X-ray Recurring Jets in an Active Region

We present simultaneous observations of three recurring jets in EUV and soft X-ray (SXR), which occurred in an active region on 2007 June 5. By comparing their morphological and kinematic characteristics in these two different wavelengths, we found that EUV and SXR jets had similar locations, directions, sizes and velocities. We also analyzed their spectral properties by using six spectral lines from the EUV Imaging Spectrometer (EIS) on board Hinode, and found that these jets had temperatures from 0.05 to 2.0 MK and maximum electron densities from 6.6$\times10^{9}$ to 3.4$\times10^{10}$ cm$^{-3}$. For each jet, an elongated blue-shifted component and a red-shifted component at the jet base were simultaneously observed in Fe{\sc xii} $λ$195 and He{\sc ii} $λ$256 lines. The three jets had maximum Doppler velocities from 25 to 121 km s$^{-1}$ in Fe{\sc xii} $λ$195 line and from 115 to 232 km s $^{-1}$ in He{\sc ii} $λ$256 line. They had maximum non-thermal velocities from 98 to 181 km s$^{-1}$ in Fe{\sc xii} $λ$195 line and from 196 to 399 km s$^{-1}$ in He{\sc ii} $λ$256 line. We also examined the relationship between averaged Doppler velocities and maximum ionization temperatures of these three jets, and found that averaged Doppler velocities decreased with the increase of maximum ionization temperatures. In the photosphere, magnetic flux emergences and cancellations continuously took place at the jet base. These observational results were consistent with the magnetic reconnection jet model that magnetic reconnection between emerging magnetic flux and ambient magnetic field occurred in the lower atmosphere.