Nebular spectroscopy: A guide on H II regions and planetary nebulae

Understand

We present a tutorial on the determination of the physical conditions and chemical abundances in gaseous nebulae.

• We also include a brief review of recent results on the study of gaseous nebulae, their relevance for the study of stellar evolution, galactic chemical evolution, and the evolution of the universe.
• One of the most important problems in abundance determinations is the existence of a discrepancy between the abundances determined with collisionally excited lines and those determined by recombination lines, this is called the ADF (abundance discrepancy factor) problem; we review results related to this problem.
• Finally, we discuss possible reasons for the large t$^2$ values observed in gaseous nebulae.