1. Electron impact excitation and radiative transition rates for CrII Marcio Meléndez, Mariela Martínez, Connor Ballance, Manuel Bautista

2. Introduction [CrII] emission is seen in a variety of objects such as: line emitting photospheres, AGNs, SNRs, and circumstellar nebulae In the so-called Strontium filament of η Carinae the strength of [CrII] emission is comparable to that of [FeII] and [NiII]

3. Other species seen in the filament are Sr II, C I, Mg I, Al II, Ca I, Ca II, Sc II, Mn II, Co II, FeI, FeII, and NiII (over 600 lines)

4. The CrII target

6. A-values for forbidden transitions

7. Collision strengths

8. Algebraic recoupling from LS to fine structure 40,000 points used to represent the cross sections up to 1 Ry Effective collision strengths computed from 3000 to 15000 K

9. The CrII spectral model 163-level model for the CrII system The model includes collisional and continuum fluorescence excitation For the Strontium filament of η Car the diagnostics are consistent with previous results from [SrII] and [TiII] (i.e. T=6000K, = 10 7 cm -3, w( =35000K) = 10 -9 )

10. [TiII] diagnostics

13. Wavelength I / I(6648) Obs. Theo. 4918.26 15.7 6.38 4927.29 18.2 18.3 4984.20 2.6 1.01 6079.57 2.4 0.91 6126.31 9.7 7.23 6148.90 2.6 1.78 6153.62 3.1 0.25 6228.99 1.6 0.91 6252.34 14.9 11.70 6648.98 1.0 1.00 6652.61 1.6 1.49 6727.67 3.7 3.72 7918.45 1.3 0.51 7977.90 2.9 0.84 8335.59 1.6 0.80 8412.35 3.3 2.46 8527.00 5.7 4.50 8531.91 4.5 4.39 8568.40 2.6 8.98 8587.49 2.4 8.04 9645.09 0.2 0.98 9652.72 0.5 0.74 10069~b 2.2 2.12 10128.77 2.7 3.26

14. [CrII] emissivities

15. [CrII] spectrum Wave. (À)ObservedTheory 4582.0881.00 4582.1451.002.15 8002.2791.341.45 8127.5311.651.18 8131.9301.410.93 8310.7701.050.70 8359.9390.470.33

16. Cr abundance Assuming that Cr, Ti, and Ni have similar ionic fractions one gets that: - N(Ti)/N(Ni) ~ 60 times cosmic - N(Cr)/N(Ni) ~ 20 times cosmic