# Observations of Binary Stars with the Differential Speckle Survey Instrument. VIII. Measures of Metal-Poor Stars and Triple Stars from 2015 to 2018

## TL;DR

This study reports speckle observations of binary and trinary star systems focusing on metal-poor stars and star formation, providing new orbital data and insights into stellar mass differences related to metallicity.

## Contribution

It presents five new visual orbits of metal-poor star systems, enhancing understanding of their properties and star formation processes, with implications for stellar models.

## Key findings

- Confirmed consistency with previous astrometry and photometry.
- Discovered three short-period orbits (<4 years) for key systems.
- Found a decrease in stellar mass at fixed spectral type for metal-poor stars.

## Abstract

We present 248 speckle observations of 43 binary and 19 trinary star systems chosen to make progress in two main areas of investigation: the fundamental properties of metal poor stars and star formation mechanisms. The observations were taken at the Gemini North and South telescopes during the period 2015 July to 2018 April, mainly with the Differential Speckle Survey Instrument (DSSI), but also with a few early results from the new 'Alopeke speckle camera at Gemini North. We find that the astrometry and photometry of these observations as a whole are consistent with previous work at Gemini. We present five new visual orbits for systems important in understanding metal-poor stars, three of which have orbital periods of less than 4 years, and we indicate the degree to which these and future observations can impact our knowledge of stellar properties and star formation. In particular, we find a decrease in mass at fixed spectral type for metal poor stars versus their solar-metallicity analogues that is consistent with predictions that are made from current stellar models.