SPB star HD 50230 , in fact a hybrid B-type pulsator , has been observed by CoRoT least 137 days .
A nearly equidistant period spacing pattern are found among 8 modes which are extracted from the oscillation spectrum with more than 500 frequencies .
However , it is thought to be most likely accidental by Szewczuk et al . ( 37 ) .
In the present work , we analyze the 8 modes in depth with the \chi ^ { 2 } -matching method .
Based on the best fitting model ( model MA ) , we find that they can be well explained as a sequences of consecutive dipolar ( l,~ { } m ) = ( 1 ,~ { } 0 ) .
The period discrepancies between observations and the best fitting model are within 100 s except for the outlier which is up to 300 s. Based on the calculated CMMs , we find that , for pure g-mode oscillations , the buoyancy radius \Lambda _ { 0 } can be precisely measured with the \chi ^ { 2 } -matching method between observations and calculations .
It represents the “ Propagation time ” of the g-mode from stellar surface to center .
It is of \Lambda _ { 0 } = 245.78 \pm 0.59 ~ { } \mu Hz with a precision of 0.24 % .
In addition , we also find that HD 50230 is a metal-rich ( Z _ { init } = 0.034 - 0.043 ) star with a mass of M = 6.15 - 6.27 ~ { } { M _ { \odot } } .
It is still located on hydrogen-burning phase with central hydrogen X _ { C } = 0.298 - 0.316 ( or X _ { C } = 0.306 ^ { +0.010 } _ { -0.008 } ) , therefore has a convective core with a radius of R _ { cc } = 0.525 - 0.536 ~ { } { R _ { \odot } } ( or R _ { cc } = 0.531 ^ { +0.005 } _ { -0.006 } ~ { } { R _ { \odot } } ) .
In order to well interpret the structure of observed period spacing pattern , the convective core overshooting ( f _ { ov } = 0.0175 - 0.0200 ) and the extra diffusion mixing ( \log D _ { mix } = 3.7 - 3.9 ) should be taken into account in theoretical models .