# Presence of mixed modes in red giants in binary systems

## TL;DR

This study investigates the prevalence of mixed oscillation modes in red giants within binary systems, revealing a significant difference in mode types compared to single stars, which may be linked to binarity.

## Contribution

It demonstrates that red giants in binary systems predominantly show p-dominated mixed modes, a pattern less common in single stars, suggesting a connection between binarity and oscillation mode characteristics.

## Key findings

- 50% of binary red giants show only p-dominated modes
- Only 4% of single red giants show only p-dominated modes
- Binary fraction in the sample is approximately 8%

## Abstract

The frequencies of oscillation modes in stars contain valuable information about the stellar properties. In red giants the frequency spectrum also contains mixed modes, with both pressure (p) and gravity (g) as restoring force, which are key to understanding the physical conditions in the stellar core. We observe a high fraction of red giants in binary systems, for which g-dominated mixed modes are not pronounced. This trend leads us to investigate whether this is specific for binary systems or a more general feature. We do so by comparing the fraction of stars with only p-dominated mixed modes in binaries and in a larger set of stars from the APOKASC sample. We find only p-dominated mixed modes in about 50% of red giants in detached eclipsing binaries compared to about 4% in the large sample. This could indicate that this phenomenon is tightly related to binarity and that the binary fraction in the APOKASC sample is about 8%.