Speckle Interferometry at SOAR in 2024 and 2025

TL;DR

This paper reports extensive speckle interferometry observations at SOAR in 2024-2025, providing new measurements, resolving previously unresolved pairs, and refining binary star orbits, including for pre-main sequence systems.

Contribution

It presents a large dataset of speckle measurements, resolves over 400 pairs for the first time, and improves orbital parameters for numerous binary systems.

Findings

Resolved over 400 pairs for the first time, not seen by Gaia.

Provided orbital elements for 202 binaries, including high-eccentricity orbits.

Identified new subsystems within known binaries and characterized pre-main sequence binaries.

Abstract

Results of speckle interferometry observations at the 4.1 m SOuthern Astrophysical Research (SOAR) telescope obtained during 2024-2025 are presented. We present 5316 measurements of relative positions and magnitude differences in 3532 pairs (including 524 unpublished measures made before 2024) with median and minimum separations of 0.19" and 12 mas, respectively; non-resolutions of 1723 stars are documented as well. More than 400 pairs have been resolved here for the first time and not resolved by Gaia; among those are 222 TESS objects of interest, 46 inner subsystems in known wider binaries within 100 pc, and 43 subdwarfs. Positional measurements are used to compute or improve binary orbits; elements of 202 orbits with meaningful errors are given here, while preliminary and tentative orbits are published elsewhere. Of special note are orbits with large and accurately measured eccentricties (e.g. e=0.9866+/-0.0014 for J13038-2035) and orbits of pre-main sequence binaries. Appendix contains parameters of 86 binaries used for calibration of pixel scale and orientation.