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

## TL;DR

This tutorial explains how to determine physical conditions and chemical abundances in gaseous nebulae, reviews recent findings, and discusses key issues like the abundance discrepancy factor and temperature fluctuations.

## Contribution

It provides a comprehensive guide on nebular spectroscopy techniques and reviews recent research on nebulae's role in stellar and galactic evolution, highlighting unresolved problems.

## Key findings

- Discussion of the abundance discrepancy factor (ADF) problem.
- Review of recent results on nebulae and their evolutionary significance.
- Analysis of large temperature fluctuation (t^2) values in nebulae.

## Abstract

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.