Variation in hydrogen emission lines of the QSO PKS 0736 + 017
Significant variations of the broad hydrogen emission lines in the QSO 0736 + 017 have been found. Between 1978 and 1980 the H-beta line intensity dropped by 40-percent, and between 1985 and 1986 it increased by more than 50 percent. The H-gamma line intensity underwent a larger fractional change. Line variations occurred in less than 1 yr after variations of the underlying continuum, indicating that a major part of the broad line emission originates in a region of 1 lt-yr or smaller if it is spherical.
Zheng, W.↗