Search

We present the chemical distribution of the Milky Way, based on 2900 of u-band photometry taken as part of the Canada–France Imaging Survey. When complete, this survey will cover 10,000 of the northern sky. By combing the CFHT u-band photometry together with Sloan Digital Sky Survey and Pan-STARRS and i, we demonstrate that we are able to reliably measure the metallicities of individual stars to ∼0.2 dex, and hence additionally obtain good photometric distance estimates. This survey thus permits the measurement of metallicities and distances of the dominant main-sequence (MS) population out to approximately , and provides a much higher number of stars at large extraplanar distances than have been available from previous surveys. We develop a non-parametric distance–metallicity decomposition algorithm and apply it to the sky at and to the North Galactic Cap. We find that the metallicity–distance distribution is well-represented by three populations whose metallicity distributions do not vary significantly with vertical height above the disk. As traced in MS stars, the stellar halo component shows a vertical density profile that is close to exponential, with a scale height of around . This may indicate that the inner halo was formed partly from disk stars ejected in an ancient minor merger. [ABSTRACT FROM AUTHOR]

The Canada–France Imaging Survey (CFIS) will map the northern high Galactic latitude sky in the u-band (“CFIS-u,” 10,000) and in the r-band (“CFIS-r,” 5000), enabling a host of stand-alone science investigations, and providing some of the ground-based data necessary for photometric redshift determination for the Euclid mission. In this first contribution, we present the u-band component of the survey, describe the observational strategy, and discuss some first highlight results, based on approximately one-third of the final area. We show that the Galactic anticenter structure is distributed continuously along the line of sight, out to beyond , and possesses a metallicity distribution that is essentially identical to that of the outer disk sampled by APOGEE. This suggests that it is probably a buckled disk of old metal-rich stars, rather than a stream or a flare. We also discuss the future potential for CFIS-u in discovering star-forming dwarf galaxies around the Local Group, the characterization of the white dwarf and blue straggler population of the Milky Way, as well as its sensitivity to low surface brightness structures in external galaxies. [ABSTRACT FROM AUTHOR]