Extension of the C star rotation curve of the Milky Way to 24 kpc

TL;DR

This study extends the Milky Way's rotation curve to 24 kpc using N-type carbon stars, revealing a slight decline beyond the Solar circle, based on new spectroscopic data.

Contribution

It provides new radial velocity and distance measurements for 36 carbon stars, extending the rotation curve analysis further than previous studies.

Findings

Rotation curve extends to 25 kpc from the galactic center.

Evidence of a slight decline in rotation velocity beyond the Solar circle.

Addition of 20 new confirmed carbon stars to the dataset.

Abstract

Demers and Battinelli published, in 2007 the rotation curve of the Milky Way based on the radial velocity of carbon stars outside the Solar circle. Since then we have established a new list of candidates for spectroscopy. The goal of this paper is to determine the rotation curve of the galaxy, as far as possible from the galactic center, using N type carbon stars. The stars were selected from their dereddened 2MASS colours, then the spectra were obtained with the Dominion Astrophysical Observatory and Asiago 1.8 meter telescopes. This publication adds radial velocities and Galactrocentric distances of 36 carbon stars, from which 20 are new confirmed. The new results for stars up to 25 kpc from the galactic center, suggest that the rotation curve shows a slight decline beyond the Solar circle.