Loke, Young Tzee(NCU); Chorng-Yuan Hwang(NCU)
We studied color variabilities of QSOs at z = 0.3 - 1.2. We selected 608 QSOs, which have spectra in both the Data Release 7 (DR7) and the Data Release 12 (DR12) of the Sloan Digital Sky Survey, with redshifts between 0.3 and 1.2. We considered the colors of the QSOs by comparing the 3000Å and the 4000Å flux densities in the rest frame. We searched for the color differences of the QSOs in the DR7 and the DR12. We found that the color differences show a Gaussian distribution, with some QSOs’colors displaying significant changes. We discuss the origin of the color variabilities of these QSOs.