On the Application of Wesenheit Function in Deriving Distance to Galactic Cepheids

TL;DR

This study investigates using the Wesenheit function to accurately determine distances to Galactic Cepheids, showing it has less dispersion than traditional methods and can be effectively calibrated for distance measurements.

Contribution

The paper demonstrates the viability of the Wesenheit function for deriving Cepheid distances and calibrates it using the Large Magellanic Cloud, improving distance measurement accuracy.

Findings

Wesenheit function yields smaller dispersion than optical P-L relation.

Derived Galactic P-L relations based on Wesenheit distances.

Calibrated LMC distance modulus as 18.531 ± 0.043 mag.

Abstract

In this work, we explore the possibility of using the Wesenheit function to derive individual distances to Galactic Cepheids, as the dispersion of the reddening free Wesenheit function is smaller than the optical period-luminosity (P-L) relation. When compared to the distances from various methods, the averaged differences between our results and published distances range from -0.061 to 0.009, suggesting that the Wesenheit function can be used to derive individual Cepheid distances. We have also constructed Galactic P-L relations and selected Wesenheit functions based on the derived distances. A by-product from this work is the derivation of Large Magellanic Cloud distance modulus when calibrating the Wesenheit function. It is found to be 18.531 \pm 0.043 mag.