Speaker
Description
The majority of stars form in clusters that contain at least one massive star. Massive stars dominate the radiation field and dynamics of the cluster, but the exact impact they have on star formation is unclear. We have obtained JWST NIRSpec spectra of 100 stars in the massive Galactic star forming region NGC 3603 using the micro shutter array in high resolution mode. The targets consist of young and old pre-main sequence stars, along with main sequence stars. The spectra exhibit a rich variety of absorption and emission lines that we have used to determine spectral type, metallicity, and the accretion luminosity in the case of the pre-main sequence stars. The majority of the stars appear to exhibit sub-solar metallicity, based on best fitting Phoenix stellar models. We have found evidence of stars still accreting material with ages of more than 10 million years, contrary to what is expected in an environment with such harsh UV radiation from the massive stars. We detect Paschen alpha strongly in emission in many cases. This line has rarely been studied spectroscopically, due to its inaccessibility from the ground. We have derived the first empirical relationship between Paschen alpha and the accretion luminosity of pre-main sequence stars. We detect CO bandhead emission in a number of sources and see evidence that high levels of accretion scales inversely with CO bandhead equivalent width, in agreement with current models. Among the CO bandhead emitters, we see evidence of multiple hydrogen line emission mechanisms, from the highly broadened line widths in the Pfund series compared to the Brackett series. We have also simultaneously obtained 600 nebular spectra, and have derived the extinction properties towards NGC 3603 based on the Brackett decrements of the nebular emission spectra.
