Impact of distance determinations on Galactic structure. I. Young and intermediate-age tracers

TL;DR

This paper reviews how accurate distance measurements to young stellar objects like Cepheids and open clusters influence our understanding of the structure and evolution of the Galactic disk, emphasizing the importance of extinction law calibration.

Contribution

It introduces new approaches to constraining the interstellar extinction law and discusses their impact on distance indicators used in Galactic structure studies.

Findings

Proper extinction law treatment improves distance estimates.

Cepheids and open clusters help trace metallicity gradients.

Enhanced distance accuracy informs Galactic evolution models.

Abstract

Here we discuss impacts of distance determinations on the Galactic disk traced by relatively young objects. The Galactic disk, about 40 kpc in diameter, is a cross-road of studies on the methods of measuring distances, interstellar extinction, evolution of galaxies, and other subjects of interest in astronomy. A proper treatment of interstellar extinction is, for example, crucial for estimating distances to stars in the disk outside the small range of the solar neighborhood. We'll review the current status of relevant studies and discuss some new approaches to the extinction law. When the extinction law is reasonably constrained, distance indicators found in today and future surveys are telling us stellar distribution and more throughout the Galactic disk. Among several useful distance indicators, the focus of this review is Cepheids and open clusters (especially contact binaries in clusters). These tracers are particularly useful for addressing the metallicity gradient of the Galactic disk, an important feature for which comparison between observations and theoretical models can reveal the evolutionary of the disk.