Direct spectroscopic observations of clumping in O-star winds

TL;DR

This study provides direct spectroscopic evidence of wind clumping in massive hot stars, revealing that stochastic wind clumping is a universal feature across different evolutionary stages of such stars.

Contribution

It presents the first direct spectroscopic observations of wind clumping in various types of massive stars, demonstrating its universality regardless of evolutionary stage.

Findings

Detection of variable emission-line subpeaks indicating clumping

Clumping observed across different stellar types and stages

Clumping factors are similar in all observed stars

Abstract

We report the detection and monitoring of transient substructures in the radiation-driven winds of five massive, hot stars in different evolutionary stages. Clumping in the winds of these stars shows up as variable, narrow subpeaks superposed on their wide, wind-broadened (optical) emission lines. Similar patterns of emission-line profile variations are detected in the Of stars zeta Puppis and HD93129A, in the more evolved hydrogen-rich, luminous, Of-like WN stars HD93131 and HD93162, and in the more mass-depleted WC star in gamma2 Velorum. These observations strongly suggest that stochastic wind clumping is a universal phenomenon in the radiation-driven, hot winds from all massive stars, with similar clumping factors in all stages of mass depletion.