000007460 001__ 7460
000007460 005__ 20250204104803.0
000007460 0247_ $$2DOI$$a10.1051/0004-6361/202245588
000007460 037__ $$aSCART-2025-0091
000007460 100__ $$aHawcroft, C. 
000007460 245__ $$aX-Shooting ULLYSES: Massive stars at low metallicity. III. Terminal wind speeds of ULLYSES massive stars
000007460 260__ $$c2024
000007460 520__ $$aContext. The winds of massive stars have a significant impact on stellar evolution and on the surrounding medium. The maximum speed reached by these outflows, the terminal wind speed v∞, is a global wind parameter and an essential input for models of stellar atmospheres and feedback. With the arrival of the ULLYSES programme, a legacy UV spectroscopic survey with the Hubble Space Telescope, we have the opportunity to quantify the wind speeds of massive stars at sub-solar metallicity (in the Large and Small Magellanic Clouds, 0.5 Z⊙ and 0.2 Z⊙, respectively) at an unprecedented scale.  Aims: We empirically quantify the wind speeds of a large sample of OB stars, including supergiants, giants, and dwarfs at sub-solar metallicity. Using these measurements, we investigate trends of v∞ with a number of fundamental stellar parameters, namely effective temperature (Teff), metallicity (Z), and surface escape velocity vesc.  Methods: We empirically determined v∞ for a sample of 149 OB stars in the Magellanic Clouds either by directly measuring the maximum velocity shift of the absorption component of the C IV λλ1548-1550 line profile, or by fitting synthetic spectra produced using the Sobolev with exact integration method. Stellar parameters were either collected from the literature, obtained using spectral-type calibrations, or predicted from evolutionary models.  Results: We find strong trends of v∞ with Teff and vesc when the wind is strong enough to cause a saturated P Cygni profile in C IV λλ1548-1550. We find evidence for a metallicity dependence on the terminal wind speed v∞ ∝ Z0.22±0.03 when we compared our results to previous Galactic studies.  Conclusions: Our results suggest that Teff rather than vesc should be used as a straightforward empirical prediction of v∞ and that the observed Z dependence is steeper than suggested by earlier works.
000007460 594__ $$aNO
000007460 700__ $$aSana, H.
000007460 700__ $$aMahy, L. 
000007460 700__ $$aSundqvist, J. O.
000007460 700__ $$ade Koter, A.
000007460 700__ $$aCrowther, P. A. 
000007460 700__ $$aBestenlehner, J. M.
000007460 700__ $$aBrands, S. A.
000007460 700__ $$aDavid-Uraz, A.
000007460 700__ $$aDecin, L.
000007460 700__ $$aErba, C.
000007460 700__ $$aGarcia, M.
000007460 700__ $$aHamann, W. -R.
000007460 700__ $$aHerrero, A.
000007460 700__ $$aIgnace, R.
000007460 700__ $$aKee, N. D.
000007460 700__ $$aKubátová, B.
000007460 700__ $$aLefever, R.
000007460 700__ $$aMoffat, A.
000007460 700__ $$aNajarro, F.
000007460 700__ $$aOskinova, L.
000007460 700__ $$aPauli, D.
000007460 700__ $$aPrinja, R.
000007460 700__ $$aPuls, J.
000007460 700__ $$aSander, A. A. C. 
000007460 700__ $$aShenar, T.
000007460 700__ $$aSt-Louis, N.
000007460 700__ $$aud-Doula, A.
000007460 700__ $$aVink, J. S.
000007460 773__ $$c19$$nA105$$pAstronomy & Astrophysics$$v688$$y2024
000007460 8560_ $$flaurent.mahy@ksb-orb.be
000007460 8564_ $$s2582274$$uhttps://publi2-as.oma.be/record/7460/files/Hawcroft_XshootU_2024.pdf
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000007460 905__ $$apublished in
000007460 980__ $$aREFERD