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We report on experimental transition probabilities for thirteen forbidden [Fe II] lines originating from three different metastable Fe  levels. Radiative lifetimes have been measured of two metastable states by applying a laser probing technique on a stored ion beam. Branching ratios for the radiative decay channels, i.e. M1 and E2 transitions, are derived from observed intensity ratios of forbidden lines in astrophysical spectra and compared with theoretical data. The lifetimes and branching ratios are combined to derive absolute transition probabilities, A-values. We present the first experimental lifetime values for the two Fe II levels a 4 G 9/2 and b 2 H 11/2 and A-values for 13 forbidden transitions from a 6 S 5/2 , a 4 G 9/2 and b 4 D 7/2 in the optical region. A discrepancy between the measured and calculated values of the lifetime for the b 2 H 11/2 level is discussed in terms of level mixing. We have used the code CIV3 to calculate transition probabilities of the a 6 D-a 6 S transitions. We have also studied observational branching ratios for lines from 5 other metastable Fe II levels and compared them to calculated values. A consistency in the deviation between calibrated observational intensity ratios and theoretical branching ratios for lines in a wider wavelength region supports the use of [Fe II] lines for determination of reddening.

In the spectrum of an emission‐line region ejected from the massive star Eta Carinae, called the strontium filament (SrF), forbidden lines from many elements, in particular [Sr ii] and [Ti ii], are observed. These lines are strong in this specific region and valuable for plasma diagnostics. Forbidden lines are not easily produced in laboratory light sources and the atomic parameters for these lines can thus not be measured in a straightforward way. We use a combination of laboratory and astrophysical measurements to determine transition probabilities for the [Ti ii] lines. Lifetimes for metastable levels in Ti ii are measured using a laser probing technique on a stored ion beam at CRYRING, MSL, Stockholm. Branching fractions from some of these levels are derived from Hubble Space Telescope/STIS spectra of the SrF. The astrophysical branching fractions are combined with the experimental lifetimes to determine absolute transition probabilities. We report lifetimes for the Ti ii levels b4P3/2, b2P1/2, c2D3/2 and c2D5/2, in the range 0.29–17 s, and transition probabilities for eight parity‐forbidden lines from the levels c2D3/2 and c2D5/2, along with uncertainty estimates.