Line luminosities of Galactic and Magellanic Cloud Wolf–Rayet stars

Abstract

ABSTRACT We provide line luminosities and spectroscopic templates of prominent optical emission lines of 133 Galactic Wolf–Rayet (WR) stars by exploiting Gaia DR3 parallaxes and optical spectrophotometry, and provide comparisons with 112 counterparts in the Magellanic Clouds. Average line luminosities of the broad blue (He ii λ4686, C iii λλ4647,51, N iii λλ4634,41, and N v λλ4603,20) and yellow (C iv λλ5801,12) emission features for WN, WN/C, WC, and WO stars have application in characterizing the WR populations of star-forming regions of distant, unresolved galaxies. Early-type WN stars reveal lower line luminosities in more metal-poor environments, but the situation is less clear for late-type WN stars. LMC WC4–5 line luminosities are higher than their Milky Way counterparts, with line luminosities of Magellanic Cloud WO stars higher than Galactic stars. We highlight other prominent optical emission lines, N iv λλ3478,85 for WN and WN/C stars, O iv λλ3403,13 for WC and WO stars, and O vi λλ3811,34 for WO stars. We apply our calibrations to representative metal-poor and metal-rich WR galaxies, IC 4870 and NGC 3049, respectively, with spectral templates also applied based on a realistic mix of subtypes. Finally, the global blue and C iv λλ5801,12 line luminosities of the Large Magellanic Clouds or LMCs (Small Magellanic Clouds) are 2.6 × 1038 erg s−1 (9 × 1036 erg s−1) and 8.8 × 1037 erg s−1 (4 × 1036 erg s−1), respectively, with the cumulative WR line luminosity of the Milky Way estimated to be an order of magnitude higher than the LMC.