Spica and the annual cycle of PKS B1322-110 scintillations

Abstract

PKS B1322-110 is a radio quasar that is located only 8.5' in angular separation from the bright B star Spica. It exhibits intra-day variability in its flux density at GHz frequencies attributed to scintillations from plasma inhomogeneities. We have tracked the rate of scintillation of this source for over a year with the Australia Telescope Compact Array, recording a strong annual cycle that includes a near-standstill in August and another in December. The cycle is consistent with scattering by highly anisotropic plasma microstructure, and we fit our data to that model in order to determine the kinematic parameters of the plasma. Because of the low ecliptic latitude of PKS B1322-110, the orientation of the plasma microstructure is poorly constrained. Nonetheless at each possible orientation our data single out a narrow range of the corresponding velocity component, leading to a one-dimensional constraint in a two-dimensional parameter space. The constrained region is consistent with a published model in which the scattering material is associated with Spica and consists of filaments that are radially oriented around the star. This result has a 1% probability of arising by chance.

10 pages, 5 figures, accepted for publication in MNRAS

References in corpus (5)

• Rapid interstellar scintillation of PKS B1257-326: two-station pattern time delays and constraints on scattering and microarcsecond source structure
• The IDV source J1128+5925, a new candidate for annual modulation?
• Emergence and disappearance of micro-arcsecond structure in the scintillating quasar J1819+3845
• Intra-day variability observations of S5 0716+714 over 4.5 years at 4.8 GHz
• J1128+592: a highly variable IDV source

Cited by in corpus (10)

• ASKAP observations of multiple rapid scintillators reveal a degrees-long plasma filament
• Radio Variable and Transient Sources on Minute Timescales in the ASKAP Pilot Surveys
• Analysis of the ionized interstellar medium and orbital dynamics of PSR~J1909-3744 using scintillation arcs
• Extreme intra-hour variability of the radio source J1402+5347 discovered with Apertif
• Interstellar Scintillation of an Extreme Scintillator: PKS B1144-379
• Optical study of PKS B1322-110, the intra-hour variable radio source
• Intra-Day Variability Observations of Two Dozens of Blazars at 4.8 GHz
• Tidal disruption of "snow clouds" by unassociated stars
• The Annual Cycle in Scintillation Timescale of PMN J1726+0639
• Search for H2 cloudlets in our backyard