X-Shooting ULLYSES: Massive stars at low metallicity

X. Physical parameters and feedback of massive stars in the LMC N11 B star-forming region

¹ Institut für Physik und Astronomie, Universität Potsdam, Karl-Liebknecht-Str. 24/25, 14476 Potsdam, Germany
² Zentrum für Astronomie der Universität Heidelberg, Astronomisches Rechen-Institut, Mönchhofstr. 12–14, 69120 Heidelberg, Germany
³ Armagh Observatory and Planetarium, College Hill BT61 9DG, Armagh, Northern Ireland, UK
⁴ Department of Physics & Astronomy, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH, UK
⁵ Dpto. de Astrofísica, Universidad de La Laguna, 38205 La Laguna, Tenerife, Spain
⁶ Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Spain
⁷ Penn State Scranton, 120 Ridge View Drive, Dunmore, PA 18512, USA
⁸ Astronomický ústav, Akademie věd České republiky, Fričova 298, 251 65 Ondřejov, Czech Republic
⁹ Departamento de Ciencias, Facultad de Artes Liberales, Universidad Adolfo Ibáñez, Viña del Mar Chile
¹⁰ Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile, 782-0436 Santiago, Chile
¹¹ Instituto de Astrofísica de Andalucía, Glorieta de la Astronomía s/n, 18008 Granada, Spain
¹² Faculty of Physics, University of Duisburg-Essen, Lotharstraße 1, 47057 Duisburg, Germany
¹³ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
¹⁴ Royal Observatory of Belgium, Avenue Circulaire/Ringlaan 3, 1180 Brussels, Belgium
¹⁵ Centre for Extragalactic Astronomy, Department of Physics, Durham University, South Road, Durham DH1 3LE, UK
¹⁶ Institute for Computational Cosmology, Department of Physics, University of Durham, South Road, Durham DH1 3LE, UK
¹⁷ European Organisation for Astronomical Research in the Southern Hemisphere, Alonso de Cordova 3107, Vitacura, Santiago de Chile Chile
¹⁸ The School of Physics and Astronomy, Tel Aviv University, Tel Aviv 6997801, Israel
¹⁹ Carnegie Observatories, Las Campanas Observatory, Casilla 601, La Serena, Chile
²⁰ Department of Astrophysical Sciences, Princeton University, 4 Ivy Lane, Princeton, NJ 08544, USA
²¹ The Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101, USA
²² Lennard-Jones Laboratories, Keele University, ST5 5BG, UK
²³ Centro de Astrobiología, CSIC-INTA, Carretera de Ajalvir km 4, 28850 Torrejón de Ardoz, Madrid, Spain
²⁴ Instituto de Astronomía, UNAM, Unidad Académica en Ensenada, Km 103 Carr. Tijuana–Ensenada, Ensenada, BC 22860, Mexico

^★ Corresponding author; mau.gglez@gmail.com

Received: 3 July 2024
Accepted: 21 November 2024

Abstract

Massive stars drive the ionization and mechanical feedback within young star-forming regions. The Large Magellanic Cloud (LMC) is an ideal galaxy for studying individual massive stars and quantifying their feedback contribution to the environment. We analyze eight exemplary targets in LMC N11 B from the Hubble UV Legacy Library of Young Stars as Essential Standards (ULLYSES) program using novel spectra from HST (COS and STIS) in the UV, and from VLT (X-shooter) in the optical. We model the spectra of early to late O-type stars using state-of-the-art PoWR atmosphere models. We determine the stellar and wind parameters (e.g., T_⋆, log g, L_⋆, Ṁ, and v_∞) of the analyzed objects, chemical abundances (C, N, and O), ionizing and mechanical feedback (Q_H, Q_HeI, Q_{He II}, and L_mec), and X-rays. We report ages of 2–4.5 Myr and masses of 30–60 M_⊙ for the analyzed stars in N11 B, which are consistent with a scenario of sequential star formation. We note that the observed wind-momentum–luminosity relation is consistent with theoretical predictions. We detect nitrogen enrichment by up to a factor of seven in most of the stars. However, we do not find a correlation between nitrogen enrichment and projected rotational velocity. Finally, based on their spectral type, we estimate the total ionizing photons injected from the O-type stars in N11 B into its environment. We report log (Σ Q_H) = 50.5 ph s⁻¹, log (Σ Q_{He I}) = 49.6 ph s⁻¹, and log (Σ Q_{He II})= 44.4 ph s⁻¹, consistent with the total ionizing budget in N11.