A note on the neutrino decay line and the possibilities of its detection

Using simple physical reasoning we have estimated the wavelengths and line-widths of spectral lines arising from the decays of massive neutrinos. We have, also, to some extent, discussed the possible consequences of these decays in observable astrophysical settings. We have compared our conclusions with the predictions of the decaying dark matter (DDM) model and cold + hot dark matter ($\mathrm{C}{\nu }^2\mathrm{D}\mathrm{M}$) model.