The discovery of stellar oscillations in the K giant ι Draconis

¹ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany e-mail: zechmeister@mpia.de
² Thüringer Landessternwarte Tautenburg (TLS), Sternwarte 5, 07778 Tautenburg, Germany
³ ZAH-Landessternwarte, Königstuhl 12, 69117 Heidelberg, Germany
⁴ McDonald Observatory, University of Texas, Austin, TX 78712, USA

Received: 17 June 2008
Accepted: 12 September 2008

Abstract

ι Dra (HIP 75458) is a well-known example of a K giant hosting a substellar companion. 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 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(34.7–46.3 μHz).