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Electron impact excitation and radiative transition rates for CrII

Electron impact excitation and radiative transition rates for CrII. Marcio Meléndez, Mariela Martínez, Connor Ballance, Manuel Bautista . Introduction. [CrII] emission is seen in a variety of objects such as : line emitting photospheres, AGNs, SNRs, and circumstellar nebulae

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Electron impact excitation and radiative transition rates for CrII

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  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

  5. A-values for forbidden transitions

  6. Collision strengths

  7. 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

  8. 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, = 107 cm-3, w( =35000K) = 10-9)

  9. [TiII] diagnostics

  10. 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

  11. [CrII] emissivities

  12. [CrII] spectrum

  13. 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

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