Updated Astrometric Measurements of WDS 01398-5612 DUN 5 (p Eri), WDS 07040-4337 DUN 38 AB & WDS 07442-5027 DUN 55 AB

Abstract

WDS 01398-5612 DUN 5 (p Eri), WDS 07040-4337 DUN 38 AB & WDS 07442-5027 DUN 55AB have orbits in the 6th Catalog of Orbits of Visual Binary Stars. Using the Las Cumbres Observatory (LCO) network of telescopes DUN 5 & DUN 38 AB were imaged on November 23, 2024 and DUN 55 AB was imaged on November 26, 2024. Fifteen images of each system were obtained and analysed using the software AstroimageJ to determine separation, position angle and delta magnitude. DUN 5: The mean position angle and standard deviation was 184.65° ± 0.331, the mean separation and standard deviation was 11.321’’ ± 0.066 and the mean delta magnitude and standard deviation was 0.127 ± 0.038.  DUN 38 AB: The mean position angle and standard deviation was 124.63° ± 0.232, the mean separation and standard deviation was 21.264’’ ±  0.113 and the mean delta magnitude and standard deviation was 1.311 ± 0.024. DUN 55 AB: The mean position angle and standard deviation was 133.23° ± 0.089, the mean separation and standard deviation was 52.005’’ ± 0.067 and the mean delta magnitude and standard deviation was 0.937 ± 0.028. The published values for orbital period and semi-major axis along with the parallax data of the A component obtained from GAIA DR3 were used to estimate the mass sum of each system. In addition, using the GAIA DR3 parallax data and the measures of apparent separation (reported in this paper), the physical separation distance between the primary and secondary stars for each system were estimated.