SIMBAD references

We present the first complete far-infrared spectrum (43-197 µm) of M82, the brightest infrared galaxy in the sky, taken with the Long Wavelength Spectrometer of the Infrared Space Observatory (ISO). We detected seven fine structure emission lines, [O I] 63 and 145 µm, [O III] 52 and 88 µm , [N II] 122 µm, [N III] 57 µm, and [C II] 158 µm, and fitted their ratios to a combination starburst and photodissociation region (PDR) model. The best fit is obtained with H II regions with n=250 cm^–3, an ionization parameter of 10^–3.5, and PDRs with n=10^3.3 cm^–3 and a far-ultraviolet flux of G₀=10^2.8. We applied both continuous and instantaneous starburst models, with our best fit being a 3-5 Myr old instantaneous burst model with a 100 M_☉ cutoff. We also detected the ground-state rotational line of OH in absorption at 119.4 µm. No excited level OH transitions are apparent, indicating that the OH is almost entirely in its ground state with a column density ∼4x10¹⁴ cm^–2. The spectral energy distribution over the long-wavelength spectrometer wavelength range is well fitted with a 48 K dust temperature and an optical depth, τ_Dust ∝ λ^–1.