In this introduction, we have started from the observation that petroleum fractions may exist in certain protoplanetary nebulae.
Thus, these petroleum fractions can be used as model for the matter present in the interstellar medium or in the protoplanetary nebulae.
An average-size star will then shed its outer layers as a planetary nebula.
Much of the interstellar gas as well as gaseous nebulae are plasmas.
Star-forming regions within the nebulae encountered may thus be seeded by significant numbers of microorganisms.
It has been supposed that the formation of macromolecular material was probably related to thermal alteration in the solar nebula or the meteorite parent body.
The constraints for its formation in the solar nebula are too demanding so it cannot be formed at all under those conditions.
These include the 21 and 30 mm emission features, and the extended red emission observed in protoplanetary nebulae and planetary nebulae.
