Addressing Outstanding Problems in the Physics of Massive Stars with the Line Emission Mapper X-ray Probe

TL;DR

The paper advocates for high-resolution soft X-ray spectroscopy of early-type stars using the Line Emission Mapper X-ray Probe, highlighting its enhanced sensitivity and potential to advance understanding of massive star physics.

Contribution

It introduces the capabilities of the LEM X-ray Probe for studying hot star systems, emphasizing its improved sensitivity and resolution over current instruments.

Findings

Enables observation of fainter and more distant high-mass stars.

Allows short-exposure time domain studies of source variability.

Will provide breakthroughs in understanding stellar winds, shocks, and feedback processes.

Abstract

We present some of the salient aspects of the scientific motivation for high resolution soft X-ray spectroscopy of early-type stars with the Line Emission Mapper X-ray Probe. The major strength of {\it LEM} for hot star physics is its large effective area, aided by the inherent energy resolution of its microcalorimeter that readily achieves resolving powers of 1000 and obviates the need for relatively inefficient dispersive optical elements. This increased sensitivity enables much fainter and more distant high mass stars to be observed than are accessible with present-day facilities, greatly increasing the pool of potential targets. For brighter sources, the sensitivity opens up time domain studies, wherein sufficient signal can be garnered in short order and exposure times, probing source variations on ks timescales. We argue that these capabilities of {\it LEM} will yield breakthroughs in all types of hot star systems, from understanding single OB and WR star winds and how they vary with metallicity, to probing the shocks of colliding wind systems and the magnetically channeled winds of magnetic OB stars. {\it LEM} will also study the energetics of WR star bubbles and feedback from their powerful pre-SN stellar winds.