Differential Rotation - Photometric Period Variation Relationship in Chromospherically Active Stars
Project no. 24150 · Status: Kapanmış · 2022
Summary
<p>In late type stars, differential rotation and convection are the two basic elements that determine the level of chromospheric activity. The magnitude of the differential rotation can be determined by observations. The rotation period of a chromospherically active star exhibiting sun-like spot activity can be determined with great approximation from photometric observations. The rotation period determined in this way is called the "photometric period". Although the photometric period is not the "true" rotation period of the star, it can take values within a certain range. According to the definition of differential rotation, different latitudes on the surface of a star have different rotation periods. Accordingly, spots appearing at different latitudes on the surface of a chromospherically active star showing spot activity will have different rotation periods. If the star is observed for many years, it will be seen that the photometric periods indicated by the spots formed at different latitudes will have different values within a certain range. This is key to determine a lower limit for the magnitude of the differential rotation. The lower limit for the magnitude of the differential rotation can be determined with the help of different values taken over time by the photometric period determined by observations. This is very important for testing the predictions of magnetohydrodynamic models regarding chromospheric activity. The wider the time interval covered by photometric observations, the closer to accuracy the differential rotation magnitude to be obtained will be.</p><p><br></p><p>Although the method of determining the differential rotation over photometric periods has been applied to some stars to date, a quantitative investigation of the relationship between differential rotation and photometric period change has not been conducted on a large sample group, since it has been applied to a certain or a few stars. Within the scope of this project, stars that have not been studied, regardless of whether they are single or double, will be selected and long-term photometric data of these stars will be compiled from sky scanning databases, and photometric period analysis will be carried out for each star with basic statistical methods.</p>