Mode Switching and Subpulse Drifting in PSR B0826-34

We present high-quality observations of PSR B0826-34 at 1374 MHz. The emission from this pulsar exhibits strong bursts of pulses followed by long periods of `null' pulses. When it is strong, the radiation extends through the whole pulse period. We show for the first time that there is weak emission during the `null' phases, which should therefore be considered to be a different mode rather than a null. During this weak mode the profile is similar to that observed in the strong mode at low radio frequency. Using a phase-tracking method, the pattern of drifting subpulses during the strong mode is seen to be coherent across the whole profile. The drift rate is variable and includes positive and negative values. Thirteen subpulse bands have been directly observed, covering the whole longitude range. The subpulses and their spacings ($P_2$) are wider in one half of the profile than those in the other half. This difference, and the variation of observed $P_2$ within the two regions, can be accounted for if the magnetic pole is inclined to the rotation axis by about 0.5 degrees. These two regions appear to represent radiation from outer and inner cones. The intensity modulation of subpulses in all longitude ranges is related to the magnitude of the drift rate.Comment: 8 pages, 10 figures. Accepted for publication in MNRA

A detection of the layered structure of nearby open clusters

We applied the newly developed rose diagram overlay method to detect the layered structure of 88 nearby open clusters ($\leq$500~pc) on the three projections after the distance correction of their member stars, based on the catalog in literature. The results show that with the rose diagram overlay method, a total of 74 clusters in our sample have a layered structure, while the remaining clusters are without a clear layered structure. We for the first time defined the layered structure parameters for the sample clusters. Meanwhile, we found that the layered circle core area ($s$) has a strong positive correlation with the number of cluster members, while the kernel instability index ($\eta$) has a strong negative correlation with the number of cluster members. Our study provides a novel perspective for the detection of the layered structure of open clusters.Comment: 11 pages, 9 figures, 6 tables, accepted for publication in A&