Proper motions with Subaru I. Methods and a first sample in the Subaru Deep Field

TL;DR

This paper details the methods used to identify stars with proper motions in deep Subaru images over six years, presenting a sample of 99 high-significance moving stars and discussing their possible populations.

Contribution

It introduces a novel reduction and identification technique for proper motions in deep imaging data and provides the first sample of such stars in the Subaru Deep Field.

Findings

99 stars with significant proper motions identified

Approximately 9 candidates may be white dwarfs

Discovery of potential extremely metal-poor subdwarfs

Abstract

We search for stars with proper motions in a set of twenty deep Subaru images, covering about 0.28 square degrees to a depth of i ~ 25, taken over a span of six years. In this paper, we describe in detail our reduction and techniques to identify moving objects. We present a first sample of 99 stars with motions of high significance, and discuss briefly the populations from which they are likely drawn. Based on photometry and motions alone, we expect that 9 of the candidates may be white dwarfs. We also find a group of stars which may be extremely metal-poor subdwarfs in the halo.