Inside the Iron Curtain: A Long Term Look at the Iron Stars XX Oph and AS 325

TL;DR

This study provides a long-term observational analysis of the binary systems XX Oph and AS 325, revealing their orbital characteristics, spectral features, and variability over several decades.

Contribution

It offers the first detailed long-term photometric and spectroscopic study of these two Iron Stars, refining their orbital parameters and stellar classifications.

Findings

AS 325 is an eclipsing binary with a 512.943-day period.

XX Oph is a non-eclipsing system with complex light curve behavior.

Spectroscopic data confirms Be+K2.5 II and Be+M6 II stellar components.

Abstract

The Iron Stars XX Oph and AS 325, both binaries consisting of a Be + late K,M II star present remarkable optical spectra. Low velocity, dense winds from the late type star collide with high velocity, optically thin material expelled from the hot Be star producing a plethora of emission lines and complex P Cygni absorption profiles. The members of the American Association of Variable Star Observers have faithfully observed XX Oph for 85 years and AS 325 for 32 years. This long term photometric monitoring has revealed AS 325 to be an eclipsing system while XX Oph shows a complex light curve behavior. We present archival and recent photometry, new high-resolution optical imaging, and new high-resolution optical spectroscopy of the two stars. The orbital period of AS 325 is refined as 512.943 days and the stellar components are Be+K2.5 II. XX Oph is shown to be non-eclipsing and consists of Be+M6II stars.