The Quintuplet Cluster II. Analysis of the WN stars

Abstract

Based on $K$-band integral-field spectroscopy, we analyze four Wolf-Rayet stars of the nitrogen sequence (WN) found in the inner part of the Quintuplet cluster. All WN stars (WR102d, WR102i, WR102hb, and WR102ea) are of spectral subtype WN9h. One further star, LHO110, is included in the analysis which has been classified as Of/WN? previously but turns out to be most likely a WN9h star as well. The Potsdam Wolf-Rayet (PoWR) models for expanding atmospheres are used to derive the fundamental stellar and wind parameters. The stars turn out to be very luminous, $\log (L/L_{\odot })>6.0$, with relatively low stellar temperatures, $T_{\ast }\approx$ 25--35\,kK. Their stellar winds contain a significant fraction of hydrogen, up to $X_{\mathrm{H}}\sim 0.45$ (by mass). We discuss the position of the Galactic center WN stars in the Hertzsprung-Russell diagram and find that they form a distinct group. In this respect, the Quintuplet WN stars are similar to late-type WN stars found in the Arches cluster and elsewhere in the Galaxy. Comparison with stellar evolutionary models reveals that the Quintuplet WN stars should have been initially more massive than 60\,$M_{\odot }$. They are about 2.1 to 3.6\,Million years old, and might still be central hydrogen burning objects. The analysis of the spectral energy distributions of the program stars results in a mean extinction of $A_K=3.1\pm 0.5$\,mag ($A_V=27\pm 4$\,mag) towards the Quintuplet cluster.

9 pages, 7 figures, 4 tables, article published in A&A (with better layout)

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Cited by in corpus (15)

• The Galactic WC stars: Stellar parameters from spectral analyses indicate a new evolutionary sequence
• Wolf-Rayet stars in the Small Magellanic Cloud: I. Analysis of the single WN stars
• The Central 300 pc of the Galaxy probed by infrared spectra of H${}_3^{+}$ and CO: part I. Predominance of warm and diffuse gas and high H${}_2$ ionization rate
• Driving classical Wolf-Rayet winds: A Γ- and Z-dependent mass-loss
• Grids of stellar models with rotation VII: Models from 0.8 to 300 M${}_{\odot }$ at super-solar metallicity (Z = 0.020)
• The Quintuplet Cluster III. Hertzsprung-Russell diagram and cluster age
• Isolated massive stars in the Galactic center: The dynamic contribution from the Arches and Quintuplet star clusters
• The orbital motion of the Quintuplet cluster - a common origin for the Arches and Quintuplet clusters?
• Circumstellar discs in Galactic centre clusters: Disc-bearing B-type stars in the Quintuplet and Arches clusters
• 2D kinematics of massive stars near the Galactic Center
• WR 120bb and WR 120bc: a pair of WN9h stars with possibly interacting circumstellar shells
• Emission Lines in the Near-infrared Spectra of the Infrared Quintuplet Stars in the Galactic Center
• Massive stars in the young cluster VVV CL074
• Near-Eddington mass loss of hydrogen-rich Wolf-Rayet stars
• Radio observations of massive stars in the Galactic centre: The Quintuplet cluster