Emission Lines in the Near-infrared Spectra of the Infrared Quintuplet Stars in the Galactic Center

TL;DR

This study detects emission lines in the near-infrared spectra of five dust-embedded stars in the Galactic Center's Quintuplet Cluster, confirming their classification as dusty late-type carbon Wolf-Rayet stars despite high extinction and dust obscuration.

Contribution

First near-infrared spectroscopic detection of emission lines in these stars, revealing their Wolf-Rayet nature amidst challenging observational conditions.

Findings

Emission lines from ionized carbon and helium confirmed Wolf-Rayet classification.

Spectroscopy revealed broad emission lines characteristic of dusty late-type carbon Wolf-Rayet stars.

Detection of these lines supports the binary nature of some stars with pinwheel dust morphologies.

Abstract

We report the detection of a number of emission lines in the 1.0--2.4~$\mu$m spectra of four of the five bright infrared dust-embedded stars at the center of the Galactic center's Quintuplet Cluster. Spectroscopy of the central stars of these objects is hampered not only by the large interstellar extinction that obscures all objects in the Galactic center, but also by the large amounts of warm circumstellar dust surrounding each of the five. The pinwheel morphologies of the dust observed previously around two of them are indicative of Wolf-Rayet colliding wind binaries; however, infrared spectra of each of the five have until now revealed only dust continua steeply rising to long wavelengths and absorption lines and bands from interstellar gas and dust. The emission lines detected, from ionized carbon and from helium, are broad and confirm that the objects are dusty late-type carbon Wolf-Rayet stars.