First evidence of solar-like oscillations in delta Scuti stars

Vichi Antoci
Event Date and Time: 
Mon, 2011-11-07 16:00 - 17:00
Hennings 318
Local Contact: 
Jaymie Matthews
Intended Audience: 
Helioseismology is a mature field that has led to remarkably accurate knowledge of the solar interior. With the success of the MOST, CoRoT and Kepler space missions, asteroseismology of solar-like oscillators has begun to make similar contributions to our knowledge of the interiors of stars cooler than about 6500 K. This has been achieved through the study of high-overtone acoustic oscillations stochastically excited in the outer convection zones of these stars. Theoretical predictions suggest that similar oscillations should exist in hotter, more massive pulsating stars known as delta Scuti stars. However, up to now, no such oscillations have been observed, seriously questioning our understanding of the physics occurring in the outer layers of these stars. Using ultra-precise data from the Kepler mission, I present the first evidence of these predicted pulsations in the delta Scuti star HD 187547. Our detection made HD 18547 a unique astrophysical laboratory for testing different convective models: its effective temperature is higher than expected so that theory must be modified to explain its oscillations. Since the two different types of pulsation measured in the star (delta Scuti-type coherent and stochastically excited) are sensitive to different interior layers, our discovery should lead to significant improvements in stellar structure and evolution models.
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