Observations with the Differential Speckle Survey Instrument. X. Preliminary Orbits of K Dwarf Binaries and Other Stars

TL;DR

This paper presents speckle observations of binary stars using advanced instruments, deriving new orbital data and stellar masses, especially focusing on K dwarf binaries, to improve understanding of their orbital properties.

Contribution

It provides the first visual and spectroscopic-visual orbits for several binary systems, with high-precision mass measurements and insights into K dwarf binary orbital characteristics.

Findings

Derived 25 new visual orbits and one spectroscopic-visual orbit.

Achieved measurement uncertainties of ~2 mas in separation and 1-2° in position angle.

Indicated that K dwarf binaries tend not to have low-eccentricity orbits at certain separations.

Abstract

This paper details speckle observations of binary stars taken at the Lowell Discovery Telescope, the WIYN Telescope, and the Gemini telescopes between 2016 January and 2019 September. The observations taken at Gemini and Lowell were done with the Differential Speckle Survey Instrument (DSSI), and those done at WIYN were taken with the successor instrument to DSSI at that site, the NN-EXPLORE Exoplanet Star and Speckle Imager (NESSI). In total, we present 378 observations of 178 systems and we show that the uncertainty in the measurement precision for the combined data set is ~2 mas in separation, ~1-2 degrees in position angle depending on the separation, and $\sim$0.1 magnitudes in magnitude difference. Together with data already in the literature, these new results permit 25 visual orbits and one spectroscopic-visual orbit to be calculated for the first time. In the case of the spectroscopic-visual analysis, which is done on the trinary star HD 173093, we calculate masses with precision of better than 1% for all three stars in that system. Twenty-one of the visual orbits calculated have a K dwarf as the primary star; we add these to the known orbits of K dwarf primary stars and discuss the basic orbital properties of these stars at this stage. Although incomplete, the data that exist so far indicate that binaries with K dwarf primaries tend not to have low-eccentricity orbits at separations of one to a few tens of AU, that is, on solar-system scales.