Anchoring the Distance Scale via X-ray/IR Data for Cepheid Clusters: SU Cas

TL;DR

This study combines X-ray, infrared, and proper motion data to precisely determine the distance to the Cepheid SU Cas within its cluster, aiding in calibrating cosmic distance measurements.

Contribution

It introduces a multi-wavelength approach to accurately measure Cepheid distances, enhancing the calibration of the cosmic distance scale.

Findings

Cluster distance: 405+-15 pc

Consistent distance measurements: ~414 pc

Potential to refine H_0 calibration

Abstract

New X-ray (XMM-Newton) and JHKs (OMM) observations for members of the star cluster Alessi 95, which Turner et al.(2012) discovered hosts the classical Cepheid SU Cas, were used in tandem with UCAC3 (proper motion) and 2MASS observations to determine precise cluster parameters: E(J-H)=0.08+-0.02 and d=405+-15 pc. The ensuing consensus among cluster, pulsation, IUE, and trigonometric distances (d=414+-5(se)+-10(sd) pc) places SU Cas in a select group of nearby fundamental Cepheid calibrators (Delta Cep, Zeta Gem). High-resolution X-ray observations may be employed to expand that sample as the data proved pertinent for identifying numerous stars associated with SU Cas. Acquiring X-ray observations of additional fields may foster efforts to refine Cepheid calibrations used to constrain H_0.