On August 14, The Astrophysical Journal published new results about Slowly Pulsating B (SPB) stars reported by WU Tao and LI Yan, who are working in Stellar Astrophysics Group of Yunnan Observatories, Chinese Academy of Sciences. By high-precision asteroseismology analysis, they precisely determined inner structure and evolutionary status of SPB Star HD 50230.
SPB stars are main-sequence stars with 2.5 to 8 Msun. Its light-curve shows 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 and more observations of SPB stars are available.
WU & LI 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, from model calculations and analyses.
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 which they developed in the 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.
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, element diffusion. “Asteroseismology can be used to probe stellar inner detail information via the propagation of oscillation waves”, said WU, “its development provides researchers a wonderful opportunity to learn the inner structure and evolutionary status of SPB stars and relevant physical processes.”
Contact:
WU Tao,Yunnan Observatories, CAS
wutao@ynao.ac.cn
