The Distribution of the Elements in the Galactic Disk II. Azimuthal and Radial Variation in Abundances from Cepheids

TL;DR

This study analyzes the distribution of chemical abundances in Cepheids across the galactic disk, revealing a consistent radial metallicity gradient and no significant azimuthal variation within the surveyed region.

Contribution

It expands the Cepheid sample by 35%, especially in azimuthal coverage, providing new insights into the galactic disk's chemical abundance distribution.

Findings

Radial metallicity gradient of -0.055 dex/kpc.

No azimuthal dependence in element abundances.

Increased coverage improves understanding of galactic disk composition.

Abstract

This paper reports on the spectroscopic investigation of 101 Cepheids in the Carina region. These Cepheids extend previous samples by about 35% in number and increase the amount of the galactic disk coverage especially in the direction of l \approx 270{\deg}. The new Cepheids do not add much information to the radial gradient, but provide a substantial increase in azimuthal coverage. We find no azimuthal dependence in abundance over an 80{\deg} angle from the galactic center in an annulus of 1 kpc depth centered on the Sun. A simple linear fit to the Cepheid data yields a gradient d[Fe/H]/dRG = -0.055 \pm 0.003 dex/kpc which is somewhat shallower than found from our previous, smaller Cepheid sample.