The Discovery of Stellar Oscillations in the K Giant $\iota$ Dra

TL;DR

This study confirms the presence of a long-lived substellar companion around the K giant $$ Dra through extended radial velocity measurements, and also detects solar-like oscillations, providing insights into stellar behavior and planetary systems.

Contribution

The paper provides the first detection of stellar oscillations in a K giant star with a confirmed substellar companion, refining orbital parameters and revealing additional companions.

Findings

Confirmed long-term radial velocity coherence supporting the companion hypothesis.

Refined orbital period to 511 days with a linear trend indicating another companion.

Detected solar-like oscillations with frequencies around 3-4 d$^{-1}$.

Abstract

$\iota$ Dra (HIP 75458) is a well-known example for a K giant hosting a substellar companion since its discovery by Frink et al. (2002). We present radial velocity measurements of this star from observations taken with three different instruments spanning nearly 8 years. They show more clearly that the RV period is long-lived and coherent thus supporting the companion hypothesis. The longer time baseline now allows for a more accurate determination of the orbit with a revised period of P=511 d and an additional small linear trend, indicative of another companion in a wide orbit. Moreover we show that the star exhibits low amplitude, solar like oscillations with frequencies around 3-4 d$^{-1}$ (34.7-46.3 $\mu$Hz).