The Variability of the Optical Brightness and Polarization of the Quasistellar Radio Source 3c 345
Citations Over TimeTop 10% of 1968 papers
Abstract
Photometric data obtained from 1965 to 1967 and polarization measurements made in 1967 are given for the variable quasi-stellar radio source 3C 345. An analysis of the observations shows that they are consistent with the optical radiation having three components: A, an essentially unpolarized constant component; B, a component having about 17 per cent linear polarization which varies both in brightness and position angle with a time scale of months; and C, a component which has a high (but undetermined) amount of linear polarization and which has a time-scale of the order of a few days. Component C takes the form of outbursts which have a mean period of about 80 days. There is oniy one chance in several hundred that this periodicity could come from a random distribution. There is also a pattern in the phases of these outbursts in the 80-day period which indicates the existence of a 321.5-day period. There is about one chance in eighty that this longer periodicity could be fortuitous. It is speculated that the most probable cause of these light variations is the rotation of a single massive body or perhaps the orbital motion of a close binary system in an optically thick envelope It is presumed that the slowly varying component arises from an extended region on the object, while the more rapidly varying component is caused by smaller active regions (which radiate non-isotropically) in transit across the face of the object