# Petersen Diagram Revolution

## TL;DR

This paper reviews recent advances in the Petersen diagram for classical pulsators, highlighting new types of multiperiodic variability discovered through OGLE data, including radial, non-radial, and modulated pulsations.

## Contribution

It presents a comprehensive analysis of OGLE data leading to the discovery of new multiperiodic pulsation forms and discusses initial theoretical explanations.

## Key findings

- Extension of known multiperiodic variables in the Petersen diagram
- Discovery of new radial-non-radial pulsators
- Identification of stars with modulation on top of beat pulsation

## Abstract

Over the recent years, the Petersen diagram for classical pulsators, Cepheids and RR Lyr stars, populated with a few hundreds of new multiperiodic variables. We review our analyses of the OGLE data, which resulted in the significant extension of the known, and in the discovery of a few new and distinct forms of multiperiodic pulsation. The showcase includes not only radial mode pulsators, but also radial-non-radial pulsators and stars with significant modulation observed on top of the beat pulsation. First theoretical models explaining the new forms of stellar variability are briefly discussed.