English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Accurate determination of mass-loss rates from massive stars is important tounderstanding stellar and galactic evolution and enrichment of the interstellarmedium. Large-scale structure and variability in stellar winds have significanteffects on mass-loss rates. Time-series observations provide directquantification of such variability. Observations of this nature are availablefor some Galactic early supergiant stars but not yet for stars in lowermetallicity environments such as the Magellanic Clouds. We utilise ultravioletspectra from the Hubble Space Telescope ULLYSES program to demonstrate that thepresence of structure in stellar winds of supergiant stars at low metallicitiesmay be discerned from single-epoch spectra. We find evidence that, for givenstellar luminosities and mean stellar wind optical depths, structure is moreprevalent at higher metallicities. We confirm, at Large Magellanic Cloud (0.5Z_solar), Small Magellanic Cloud (0.2 Z_solar) and lower (0.14 -- 0.1 Z_solar)metallicities, earlier Galactic results that there does not appear to becorrelation between the degree of structure in stellar winds of massive starsand stellar effective temperature. Similar lack of correlation is found withregard to terminal velocity of stellar winds. Additional and revised values forradial velocities of stars and terminal velocities of stellar winds arepresented. Direct evidence of temporal variability, on timescales of severaldays, in stellar wind at low metallicity is found. We illustrate that narrowabsorption components in wind-formed profiles of Galactic OB stellar spectraremain common in early B supergiant spectra at low metallicities, providingmeans for better constraining hot, massive star mass-loss rates.

Optically-thick Structure in Early B Type Supergiant Stellar Winds at Low Metallicities