Hunting the Coolest Dwarfs: Methods and Early Results

TL;DR

This paper details a survey using the Gemini camera to identify cool, low-temperature companions around nearby high proper motion stars, successfully discovering a new companion and re-identifying a known one.

Contribution

It introduces a method combining multi-epoch imaging and proper motion analysis to detect cool stellar companions around old stars, with early results from the Gemini survey.

Findings

Discovered a new companion to GJ 660.1 at ~120AU

Re-discovered the T8.5 companion to GJ 1263

Demonstrated the effectiveness of multi-epoch proper motion analysis

Abstract

We present the methods and first results of a survey of nearby high proper motion main sequence stars to probe for cool companions with the Gemini camera at Lick Observatory. This survey uses a sample of old (age > 2 Gyr) stars as targets to probe for companions down to temperatures of 500 K. Multi-epoch observations allow us to discriminate comoving companions from background objects. So far, our survey successfully re-discovers the wide T8.5 companion to GJ 1263 and discovers a companion to the nearby M0V star GJ 660.1. The companion to GJ 660.1 (GJ 660.1B) is ~4 magnitudes fainter than its host star in the J-band and is located at a projected separation of ~120AU. Known trigonometric parallax and 2MASS magnitudes for the GJ 660.1 system indicate a spectral type for the companion of M9 +/- 2.