Emission lines from stars \"intrinsically\" have some widths to their profiles (

Question

Emission lines from stars "intrinsically" have some widths to their profiles (as in Fig. 4.4, 4.6, and 4.11). Select one of the following four choices that is NOT a correct reason as to why emission lines have some widths O Stars are rotating and so in general half of the stellar materal is moving away from us while the other half moving to us. Therefore, the emission lines would appear wide do to the Doppler effect - Any atomic transition energy can be slightly different from the theoretical value because in a real ife plasma there can be external effects (i.e, due to the presence of other particles) to be taken into consideration resulting in a wider line emission. O The presence of magnetic field can split energy levels that are otherwise (non-magnetically) the same and so degenerate by means of the Zeeman splitting and those multi-line coniguration can make the degenerate line look wide than other single lines. O There exists a range for the transition energy due to Quantum Mechanics (more specifically, Heisenberg's uncertainty principle), which manifests itself as a range of wavelength (and so frequency), which corresponds to the line width.

Explanation / Answer

First option is the incorrect one. All the other options have correct explanations attached to them but in this case the explanation that has been given is incorrect. Also the stars are not rotating on their axis they do move about the center of their galaxy which usually contains an even massive object such a black hole. The radation that we recieve from stars are generally consistent in terms of their intensity and spectrum while the effects of the doppler shift which does come into play sometimes are not due to rotation about the axis of stars.

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