In a study published in The Astrophysical Journal, WU Tao and LI Yan from Stellar Astrophysics Group of Yunnan Observatories of the Chinese Academy of Sciences reported the results about Slowly Pulsating B (SPB) stars. They precisely determined inner structure and evolutionary status of SPB Star HD 50230 through high-precision asteroseismology analysis.

SPB stars are main-sequence stars with 2.5 to 8 Msun. Their light-curves show that they are multi-periods, small amplitude and irregular variables with the period of 0.8-3 days. It is very difficult to observe, especially on ground. Thanks to the uninterrupted ultra-precision space-based observations, such as CoRoT, Kepler, K2, and TESS, more observations of SPB stars are available.

Through the calculation and analysis of the model, the scientists successfully extracted an observable asteroseismic parameter, which is directly related to inner structure of SPB stars and can be used to characterize the evolutionary status of SPB stars.

They constructed an asteroseismic diagnosis diagram for slow- or non-rotation SPB stars which can be used to determine stellar evolutionary status, i.e., center hydrogen content, and to estimate stellar mass of SPB stars directly from observations without extra model calculations.

In addition, they analyzed a metal-rich and massive SPB star (HD 50230) with a method of independent high-precision asteroseismology developed in their previous work. The detailed structure and fundamental parameters of HD 50230 are precisely constrained. The differences of periods between observations and model calculations are reduced to 100 seconds.

This study revealed that the structure and evolution of massive stars are affected by many uncertain factors, such as mass loss, rotation, the transport of angular momentum, magnetic field, and element diffusion.

"Asteroseismology can be used to probe stellar inner detail information via the propagation of oscillation waves, and its development provides a wonderful opportunity to learn the inner structure and evolutionary status of SPB stars and relevant physical processes,” said WU Tao.