The Photometric Investigation of V921 Her Using the Lunar-Based Ultraviolet Telescope of Chang’e-3 Mission

Figure 1

The values of V921 Her from the linear ephemeris of (2) are presented in (a). The solid line in the panel refers to the combination of an upward parabolic variation and a cyclic change. The dashed line represents the upward parabolic variation which reveals a continuous increase in the orbital period. In (b), the values with the quadratic part in (3) removed are displayed, where a cyclic change is more clear to be seen. After both the parabolic change and the cyclic variation are removed, the residuals are plotted in (c).

(a)

(b)

(c)