The excitation of solar-like oscillations in a delta Scuti star by efficient envelope convection

TL;DR

This paper reports the first detection of solar-like oscillations in a delta Scuti star, confirming that surface convection can operate efficiently in stars twice as massive as the Sun, as predicted by models.

Contribution

It provides observational evidence supporting the existence of efficient surface convection in delta Scuti stars, validating theoretical predictions.

Findings

Detection of solar-like oscillations in HD 187547

Confirmation of efficient surface convection in delta Sct stars

Supports models predicting convective envelopes in these stars

Abstract

Delta Scuti (delta Sct) stars are opacity-driven pulsators with masses of 1.5-2.5M$_{\odot}$, their pulsations resulting from the varying ionization of helium. In less massive stars such as the Sun, convection transports mass and energy through the outer 30 per cent of the star and excites a rich spectrum of resonant acoustic modes. Based on the solar example, with no firm theoretical basis, models predict that the convective envelope in delta Sct stars extends only about 1 per cent of the radius, but with sufficient energy to excite solar-like oscillations. This was not observed before the Kepler mission, so the presence of a convective envelope in the models has been questioned. Here we report the detection of solar-like oscillations in the delta Sct star HD 187547, implying that surface convection operates efficiently in stars about twice as massive as the Sun, as the ad hoc models predicted.