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SUMMARY:Transition region spectroscopy with the Hinode/EIS instrument - Pe
 ter Young (NASA Goddard and Northumbria university)
DTSTART:20240130T140000Z
DTEND:20240130T150000Z
UID:TALK209032@talks.cam.ac.uk
CONTACT:Roger Dufresne
DESCRIPTION:The EUV Imaging Spectrometer observes the Sun in the 170-292 A
 ngstrom wavelength range\, which is dominated by coronal emission lines th
 at are mainly due to iron ions. Valuable science can still be obtained fro
 m transition region ions formed in the 0.1-0.8 MK temperature range\, and 
 some recent results are presented here. \n\nMg VII and Si VII (formed at 0
 .6 MK) produce a number of lines that are widely used for diagnostics of c
 oronal loops. However\, the standard reference wavelengths for the ions’
  lines are clearly discrepant with the wavelengths measured from EIS\, lea
 ding to erroneous Doppler velocity measurements. I demonstrate how EIS (wh
 ich does not have an absolute wavelength calibration) can be used to obtai
 n new reference wavelengths for the lines in combination with Astrophysica
 l infrared measurements. The new wavelengths for Mg VII and Si VII will be
  added to the CHIANTI database. In addition\, the EIS data show that the t
 wo ions are formed at almost exactly the same temperature and the Mg/Si re
 lative abundance is enhanced over photospheric values by about 50%.\n\n \n
 \nThe coolest ion observed by EIS (other than He II) is O IV\, formed at 0
 .1 MK. It has a rich spectrum in the EIS wavelength range with more than 2
 0 emission lines\, however most of the lines are so weak they cannot be me
 asured in normal solar conditions. A flare spectrum from 9 March 2012 is p
 resented where the lines can be measured\, and new diagnostics are present
 ed that yield an O IV temperature of log(T/K)=5.10 and a density of log(Ne
 /cm^-3)=12.55 for the flare ribbon. The results are interpreted in terms o
 f ionization and flare models.
LOCATION:MR5 DAMTP and online - ** CHANGED TIME AND LOCATION
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