English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

The oscillations of the solar-like star HD 49933 have been observedthoroughly by CoRot. Two dozens of frequency shifts, which are closely relatedwith the change in magnetic activity, have been measured. To explore theeffects of the magnetic activity on the frequency shifts, we calculatefrequency shifts for the radial and $l = 1$ p-modes of HD 49933 with thegeneral variational method, which evaluates the shifts using a spatial integralof the product of a kernel and some sources. The theoretical frequency shiftswell reproduce the observation. The magnitudes and positions of the sources aredetermined according to the $\chi^2$ criterion. We predict the source thatcontributes to both $l = 0$ and $l = 1$ modes is located at $0.48 - 0.62$Mmbelow the stellar surface. In addition, based on the assumption that $A_{0}$ isproportional to the change in the MgII activity index $\Delta{i}_{MgII}$, weobtained that the change of MgII index between minimum and maximum of HD 49933cycle period is about 0.665. The magnitude of the frequency shifts compared tothe Sun already told us that HD 49933 is much more active than the Sun, whichis further confirmed in this paper. Furthermore, our calculation on thefrequency shifts of $l = 1$ modes indicates the variation of turbulent velocityin the stellar convective zone may be an important source for the $l = 1$shifts.

Exploring the sources of p-mode frequency shifts in the CoRoT target HD 49933