Period Measurement of AGB Stars in the Outer Galactic Disk

TL;DR

This study monitored light variations of 47 AGB star candidates in the outer Galactic disk over five years, determining their periods, luminosities, distances, and deriving the Galactic rotation curve using SiO maser data.

Contribution

It provides new period measurements, distance estimates, and Galactic rotation parameters for AGB stars in the outer disk, utilizing long-term monitoring and maser observations.

Findings

Average period of 500 days for the sample stars

Mean luminosity of 10,000 solar luminosities based on period-luminosity relation

Derived Galactic rotation curve and Oort's constants

Abstract

Light variation of the 47 AGB star candidates in the outer Galactic disk has been monitored at I-band for 5 years. Periods were determined well for 18 of them and less reliably for the other 25. The average period of the objects is then 500 days. According to the period-luminosity relation, the mean luminosity of the sample stars is 10000 $\LO$. Based on the absolute luminosity derived from the period-luminosity relation and the apparent luminosity from the observation, the distances to the objects are determined. The distances calculated are slightly greater than those obtained previously on the assumption of constant luminosity of 8000 $\LO$. In addition, SiO maser emission was detected for most of the observed objects so that their radial velocities were known accurately. With the assumption of circular rotation in the Galactic disk, the rotation curve and Oort's constants were derived.