'rotational transitions in molecules'
'cannot be generated by molecules or rapid pulsations.'
'It is highly unlikely that they come from the Fourier transform of spectral lines'
This is gibberish.
Molecules do not 'transition'. Energy levels do. 'Generated by molecules'? There are no molecules in a star, too hot. Don't you mean emitted photons emitted during stellar fusion? 'Fourier transform of spectral lines'? Don't you mean a power spectrum?
Rotational spectroscopySource: https://en.wikipedia.org/wiki/Rotational_spectroscopy.Rotational spectroscopy is concerned with the measurement of the energies of transitions between quantized rotational states of molecules in the gas phase. The spectra of polar molecules can be measured in absorption or emission by microwave spectroscopy[1] or by far infrared spectroscopy. The rotational spectra of non-polar molecules cannot be observed by those methods, but can be observed and measured by Raman spectroscopy. Rotational spectroscopy is sometimes referred to as pure rotational spectroscopy to distinguish it from rotational-vibrational spectroscopy where changes in rotational energy occur together with changes in vibrational energy, and also from ro-vibronic spectroscopy (or just vibronic spectroscopy) where rotational, vibrational and electronic energy changes occur simultaneously.
For rotational spectroscopy, molecules are classified according to symmetry into spherical top, linear and symmetric top; analytical expressions can be derived for the rotational energy terms of these molecules. Analytical expressions can be derived for the fourth category, asymmetric top, for rotational levels up to J=3, but higher energy levels need to be determined using numerical methods. The rotational energies are derived theoretically by considering the molecules to be rigid rotors and then applying extra terms to account for centrifugal distortion, fine structure, hyperfine structure and Coriolis coupling. Fitting the spectra to the theoretical expressions gives numerical values of the angular moments of inertia from which very precise values of molecular bond lengths and angles can be derived in favorable cases. In the presence of an electrostatic field there is Stark splitting which allows molecular electric dipole moments to be determined.
An important application of rotational spectroscopy is in exploration of the chemical composition of the interstellar medium using radio telescopes.
Yep, definitely aliens.
I just have trouble with believing that we can determine the position of a molecule on a star 20 million light years away, and yet we aren’t exactly sure what is right under our feet.