Ion Temperature and Non-Thermal Velocity in a Solar Active Region: Using Emission Lines of Different Atomic Species

Abstract

We have studied the characteristics of the ion thermal temperature and non-thermal velocity in an active region observed by the EUV Imaging Spectrometer onboard Hinode. We used two emission lines of different atomic species (Fe XVI 262.98 Å and S XIII 256.69 Å) to distinguish the ion thermal velocity from the observed full width at half-maximum. We assumed that the sources of the two emission lines are the same thermal temperature. We also assumed that they have the same non-thermal velocity. With these assumptions, we could obtain the ion thermal temperature, after noting that M _sulfur ~ 0.6M _iron. We have carried out the ion thermal temperature analysis in the active region where the photon counts are sufficient (>4500). What we found is as follows: (1) the common ion thermal temperatures obtained by Fe XVI and S XIII are ~2.5 MK, (2) the typical non-thermal velocities are ~13 km s^-1, (3) the highest non-thermal velocities (>20 km s^-1) are preferentially observed between the bright points in Fe XVI, while (4) the hottest material (>3 MK) is observed relatively inside the bright points compared with the highest non-thermal velocity region.