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

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° in position angle depending on the separation, and ∼0.1 mag 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 ternary star HD 173093, we calculate masses with a 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 astronomical units, that is, on solar system scales.

The POKEMON Speckle Survey of Nearby M dwarfs. I. New Discoveries

“…These uncertainties were propagated throughout our analysis described in Section 3.4. These values are slightly larger than those derived in Horch et al (2017), Colton et al (2021), or Horch et al (2021); this is likely due to the faintless of our targets, and the filterless observations that took place during the April 2017 observing run. In general, filterless observations reduce the precision of our astrometry, but allow us to observe fainter companions.…”

“…We assume that the calibrations from Horch et al (2021) are also appropriate for this work, given that our targets were observed on the same runs, besides those observed in February 2020. Figure 3 of Horch et al (2021) shows the derived uncertainties from the known orbital elements that we have incorporated into our analysis. However, Horch et al (2021) did not include data from February 2020.…”

“…Figure 3 of Horch et al (2021) shows the derived uncertainties from the known orbital elements that we have incorporated into our analysis. However, Horch et al (2021) did not include data from February 2020. To reduce and analyze this data, we used pixel scale values that were approximate, and that may be updated in the future; the position angle and angular separation values from this run may therefore be updated in the future as well.…”

“…The average uncertainty in position angle is then 0.7 degrees, and the average uncertainty in delta magnitude is 0.16. When we take these values and add them in quadrature to the calibration uncertainties from Horch et al (2021), we obtain values of 5.1 mas for the average angular separation uncertainty, 2 degrees for the average position angle uncertainty, and 0.21 for the average delta magnitude uncertainty. These uncertainties were propagated throughout our analysis described in Section 3.4.…”

The POKEMON Speckle Survey of Nearby M Dwarfs. I. New Discoveries

“…Their ephemeris positions are computed based on the orbital elements, and their scale and orientation are derived from these results. We assume that the calibrations from Horch et al (2021) are also appropriate for this work, given that our targets were observed on the same runs, besides those observed in February 2020. Figure 3 of Horch et al (2021) shows the derived uncertainties from the known orbital elements that we have incorporated into our analysis.…”