1. The CHIANTI database Assessing Atomic Models for Forbidden Transitions Dr Peter Young CCLRC/Rutherford Appleton Laboratory, UK and the CHIANTI team The CHIANTI database

2. Background Astrophysical applications now account for around 1/3 of citations to the CHIANTI papers B. Ercolano (UCL) expressed interest in including CHIANTI data in the MOCASSIN photoionization code CHIANTI has been optimized for the study of electron-ionized plasmas Do we have the best data for forbidden transitions at low temperatures?

3. The CHIANTI database MOCASSIN Comparison

4. The CHIANTI database CHIANTI data CHIANTI has been optimised for electron-ionized plasmas CHIANTI does not contain the original upsilon data, only fits to the Burgess & Tully scaled upsilons Up to version 4, five point splines were fit to the data

5. The CHIANTI database 9 point splines Up to version 4 of CHIANTI, only 5 point splines were allowed to fit the collision data With version 4, the option of 9 point splines was allowed for “hard to fit” collision strengths Some early data have been re-fit with the 9-point splines to yield better accuracy at low temperatures

6. The CHIANTI database Example: Mg VII Currently DW data of Bhatia & Doschek (1995) in CHIANTI IP data available for ground transitions (Lennon & Burke 1994) –only goes up to 10 5 K –Mg VII formed at 6 x 10 5 K in electron ionized plasma

7. The CHIANTI database Summary A number of CHIANTI forbidden transitions have to be re- assessed to ensure full temperature range of upsilons is represented Also have to ensure the best R-matrix calculations are being used, even if this means merging with other data-sets Improved forbidden transitions will go into v.6 of CHIANTI